WARNING! (SEX)
(Now that I have your attention, please read the next sentences
carefully.)
There
are dangerous high voltages inside the charger and IPU. You
can be KILLED if you are careless and don't follow
the
safety instructions while building the charger and when installing the
charging harness.
At the same time, if the IMA
battery breaker switch is OFF and you follow
the warnings given in this article and in installing the charging
harness from installation instructions given from the web, it is
quite safe to work on this high voltage
system. If you are not comfortable working around high
voltage, try to enlist the help of someone that knows what to do.
(Or just wear latex gloves.)
|
Select articles from the list below.
|
Background
The
first generation Insight high voltage IMA battery is composed
of 120 special ~"D" sized Ni-MH individual cells arranged in 20
"sticks" of 6 cells each. The nominal voltage of the battery is
144
volts. A pack will typically run between 156 to 165 volts
while
in use. Ni-MH cells have a rather high self discharge rate of
up to
1% per day
and over time the capacity of the individual cells will vary.
At the same time the internal resistance of the cells will
tend to rise and not be equal between all the cells. This causes the
pack to become "out of balance" and the full capacity of the battery
can't be utilized while driving.
The IMA battery pack is normally charged (if needed) by the kinetic
energy of the car when slowing down or coasting to a stop while in
gear. This is called "regeneration". The battery can also be
charged while the engine is running in what is called a "background
charge". The background charge does not always show up on the
dashboard instrumentation. Normally there is no way to charge
the IMA battery with an external charger. More information about all this can be
found at the insightcentral.net/forums/.
Do a search for "grid charger". I also have a forum link if you have any relevant questions concerning the V2 charger or usage.
|
The battery control module (BCM) has many features to safely control
the charging of the battery so that it operates between 20% and 80% of
the IMA battery capacity. If the capacity of the battery goes
below ~10%
the BCM will not charge the battery or allow it to assist the
IMA system. This is done to protect the battery.
The digital dashboard will also display a "Check engine"
warning and an error code will be stored in the OBDII system.
Enthusiasts on insightcentral.net/forums have devised a way to
rebalance the battery cells by slowly charging the pack to
100%. Many of the 2000 to 2006 Insight IMA
batteries can be brought back to life by giving them this low current
charge for an extended period of time. Typically 0.20 to 0.35 amp is
used for 24 to 35 hours. The this low level charge allows all the cells
of
the battery to become fully charged without overheating the better
cells of the pack which will reach full charge first. The
battery will charge to ~174 volts.
Even new batteries ought to be grid charged once every 3 or 4 months
after they are 6 or 9 months old. This keeps them balanced
and will help them last longer.
The charger that does this is called a "grid charger" because it gets
it's input power from the normal home power grid (the wall
sockets). The charger is basically what auto mechanics call a
"trickle charger" because it charges at a very low rate. A
normal 12 volt car battery charger can NOT be used on the IMA battery
because the voltage and current are not correct for our purpose.
The grid charger also powers the normal Insight 12 volt IMA battery
cooling
fan to insure that the IMA battery pack doesn't overheat due to the
extended low level charge. There is also a fan inside the
grid charger to cool its components.
General
features of this charger
This
article is an idea provoking one to present how my V2 DIY grid
charger looks and to present the schematic with a parts list so you can
build one for yourself. I am not going to give a
detailed mechanical dimensions of where to drill holes etc
because the parts you buy, the case you use, the
individual parts etc will vary in size from the parts I
used. And truthfully I don't want to encourage people to copy my
designs
to sell [6/11/13].
Ready to use grid chargers from simple to very elaborate computer
controlled models can be bought through insightcentral.net/forums/
and eBay. This article describes a simple grid charger (no
fancy computer control) that can be built from components found online,
eBay
and if you are into building electronic devices, probably from your
junk
box. If you are familiar with reading schematics, soldering
and using hand tools you should have no problem building your
own charger. You also have to open the battery box
(IPU) behind the Insight seats
under the hatch storage area to install a charging harness.
You
can find information how to install the harness (some
with videos) on the Insight Central forums.
When I built this charger in November 2019 the Mean Well HLG-60H-C350A
LED power supply cost me $36. I had all the other
parts in
my "pre-owned" [junk] boxes including the used computer power
supply case, a 3" square cooling fan to replace the huge original fan,
the switches and other parts.
Naturally your cost will vary depending upon how many parts
you already have. The
total parts price is typically less than $75.
One of the aims of designing the V2 grid charger was to eliminate the
terminal strip and some of the other discrete parts used on V1 charger.
I accomplished those goals with V2.
If you can
find a local computer repair shop you can probably buy a junked ATX
power supply with a top mounted fan for
the charger case, 3" square fan and the AC line cord etc.
IMPORTANT NOTES:
The
Mean Well power supply is much longer than the average PC computer
power supply case. The Mean Well
supply will normally not fit in a side mounted fan case.
I have some junk power
supplies and one of the supplies was rated at 450 watts
output. That case is slightly larger than lower wattage supplies. The
length and width of the 450 watt supply is 6.125" x 5.875" measured at
the bottom of the case. By
bending three of the power supply mounting tabs upwards the
supply will diagonally
fit into the slightly oversize case. This is shown in the
pictures further down this article.
You will need to replace
the huge top mounted fan on the power supply case you use with a
smaller fan to gain more vertical space inside
the case. Since the grid charger really doesn't generate much heat that
needs to
be dissipated a smaller fan will work fine. So bring a ruler
when buying a junk power supply.
If you don't have a 3" square cooling fan you may have to buy
another junk supply to get the rear mounted 3" fan.
Top mounted fans tend to be much thicker and run slower than
the smaller fans.
One
builder, MparkH, a member of the insightcentral forum, mounted
his
Mean Well power supply rotated so
one side of the supply lays on the bottom of a normal computer sized
case. The case he used also has the fan located on the side
instead of on top of the case. To
read his excellent description of how he built his charger for
about $59 (not including s/h) from these plans,
click the following link, https://www.insightcentral.net/threads/olrowdy01-v2-grid-charger-build-illustrated.126021/
With
luck you may find some of the parts on the computer junk
power supply printed circuit
board to use in your
DIY charger/discharger. I found the 100K
ohm resistor on one junk power supply PCB. If the PC
computer
power supply board uses 4
individual diodes mounted close to each other on the AC high voltage
side of the PC board, one those diodes may be used in
the grid
charger (see schematic further down this article). You should
remove the small 2 pin connector on the PCB that the fan wires connect
to. It will be used on the grid charger to connect the
charger cooling fan to the charger 12 Vdc power supply.
Return to top of
"General
features of this charger"
Return to top of this file
Preparing case to build charger
The original power
supply printed
circuit board should be
removed and discarded. If the case has a 115-240 AC voltage
input selection switch mounted near the AC power cord socket it should
be
removed. The rectangular switch
opening left in the case can be used to mount the panel mount fuse
holder by
enlarging the opening with a hand tapered reamer. Luckily my
case has a rear mounted power ON-OFF switch which is now used as the
power
switch for the charger. If your case doesn't have a power
switch you will need to buy two SPST switches (SW1 and SW2).
One switch is
used
as the charge/discharge switch and the other for the charger AC power
ON-OFF switch.
I
used #4-40 sized hardware to mount the various front panel
parts
and power supplies to the bottom of the case. After the
charger was built and tested I installed
four
rubber feet on the bottom of the case where the PCB mounting holes
were located. The rubber feet
keep the bottom mounted screw
heads from snagging on the car's carpet while charging the battery and
allow
space on the bottom of the charger for air flow to act as an additional
heat sink for the Mean Well power supply..
For the V2 simple grid charger I've switched to a dual
volt/amp meter since the V1 meter isn't available on eBay
anymore.
The volt/amp meters sold now on eBay can't sense or display the
(negative) discharge current. The volt meter will show the
battery
voltage while discharging but the ampere meter will show 0.000 ma
[discharge]. Such is progress. :-(
If you
want to see a preview of what meters are available do an eBay search
for "200V 10A 4 digit meter". I've done a several hour eBay search several times but
haven't found any of the dual meters that can read the discharge current. So for now I would stick with the cheaper 4 bit
dual red meters that do not display discharge current. By using
the light bulb vs current chart (way down this article) you can select what current you want to
flow at the beginning of the discharge. Or you could buy a dedicated current meter and wire it up
on your discharge load.
The dual reading meter is powered by a
separate small isolated switch mode power supply with an output
voltage between 4
to 30 volts at less than 30 ma requirement. I used a
small 5
volt, 100 ma cell phone wall wart charger to power the
meter. The meter power supply
must have the output isolated from the AC input and chassis ground.
This is necessary because the meter negative DC power lead (thin
black wire) is internally connected to the thick black lead
which is used to measure the voltage and current of the charger.
The IMA battery charging voltage is created by the Mean Well which delivers 100 to 200 volts (depending upon the battery
voltage) at 350 ma constant
current. The V1 charger used two 45-90 V, 350ma current
limited supplies wired in series
but
they are just not offered on eBay anymore. The Mean Well
supply will not taper the charge current as the battery reaches 100%
(~174 volts) since the voltage is in the area of constan current..
The Mean Well
supplies are normally used
to power strings of LEDs for lighting or special affects. The Mean Well
supply is protected for short circuit, over temperature and other
features which are desirable. The power supply case is aluminum and
will dissipate heat much better than the plastic cases used on other
LED supplies. Even more
heat can be dissipated by mounting the supply on the bottom of
the
metal case of the grid charger. The Mean Well is a well
designed,
sturdy supply which is much better than the cheap supplies used in V1
of the grid charger/discharger.
I use a series output diode on the positive DC output lead of
the Mean Well to keep the IMA
voltage from back biasing the supply when the front panel
switch is set to discharge mode.
This allows you to read the battery voltage while discharging
the battery. The 100K resistor is used to speed up the
discharge of the high
voltage of the Mean Well supply when you switch to "Discharge" or power
OFF.
Without the resistor (commonly called a "bleeder resistor")
the supply will take much longer to reduce the high voltage to safe
levels if you need to tinker inside the case. I connected D1
and R1 right near the charging harness socket on the front panel.
NOTES:
If a diode(s) is
used on the charging harness or within the IPU case to prevent
battery voltage from appearing on the charging cable, the multimeter
will not be able to read the IMA battery voltage when the battery is
not being charged. Unfortunately you will also not be able to
do a discharge cycle of the battery to increase it's life with a
diode(s)
inside the IPU case. For that reason I you should
not
install any
diodes in the high voltage portion of the charging harness.
While you have the IPU open to install the charging
cable, check the gap around the battery cooling fan. Typically there
will be a ragged gap in the plastic housing with a space up to
1/4" wide along the fan sides. Use some RTV or other
flexible
caulking to fill in the gap to increase the cooling affect of the fan.
As a safety feature I would install a fuse on the positive
high voltage lead when you install the charging harness in the IPU. A
panel mount
fuse holder can be mounted on the IPU case so you can change the fuse
without opening the IPU case. I prefer the panel mount fuse
because you are trying to protect the harness wiring inside the case if
there is an external short. The 2 amp fuse should be
rated for 250 volts DC. A DC fuse is designed
to quench any
arcing if the fuse blows to prevent it from starting a fire inside your
car! A DC fuse can generally be identified by the white
ceramic looking body between the metal end caps.
Return
to top of "Preparing case to build charger"
Return
to top of this file
Construction and description of
how to build a grid charger
|
 |
|
This is a
preview of what the V2 grid charger looks like while charging my
battery. You need to use a 4 digit meter so tenths
of a volt are shown. As the charge proceeds the battery voltage rise
decreases
drastically. With the V1 version where the power supply
charge current was
rated to be 300 ma, the battery voltage rise slowed to 0.2 volts
per hour after reaching ~172 volts! Without seeing the 1/10s
volt display you would not realize that the battery still needed to be
charged for a good bit of additional time.
I found that the dual meters with blue LEDs are almost impossible to
read during the day when viewed
at an
angle to the
front panel. For that
reason I strongly recommend buying a 4 digit meter
with both displays being red.
The 0.5 digit in the above picture appears to not be lit properly.
It really was lit to the eye when the picture was
taken.
Even though the meter updates many times per second the camera shutter
was even faster and it caught the .5 not quite fully lit.
The left side 4 pin Molex connector is the charging harness
socket. I used the normal computer power supply convention of the
yellow wire being a higher voltage than the red wire. The two
black wires are not common ground connections but rather the left black
wire is the negative lead for the high voltage (yellow) wire and the
right black wire is the negative lead for the 12 volt fan voltage (red)
wire.
the SPST switch is the charge/discharge switch which turns OFF
the Mean Well supply during discharge, the dual meter and finally the
two pin discharge cable socket. The AC power switch is
located next to the rear 120 Vac socket on this
power supply case.
For convenience to identify which switch I'm writing about I
will call the charge/discharge switch the "mode" switch from now on.
To
make it easy to remember what mode the switch is in I
would mount it so when the switch handle is pointed upwards that is the
charging mode. Down will be the discharge mode.
Easy to remember, up to charge, down to discharge the battery.
When the mode switch is set to the charge mode with the
charging harness not connected the volt meter will read ~200
Vdc and zero current flow. If the charging cable is plugged in the meter
will indicate
the IMA battery voltage and the charging current accurate to 3 decimal places. 0.350 A = 350 ma.
When the mode switch is set to the discharge mode with the discharge
load -not- plugged in the volt/amp meter will both read zero.
While discharging the meter will display the battery voltage and
000.0 A discharge current.
|
|
To
see an enlarged view of these pictures, left click on the
picture.

This is the rear of the charger showing the rear mounted ON-OFF power
switch, the panel mount fuse holder and the 120 Vac socket.
Use a 2 Amp DC fuse.
The fuse holder is mounted where the original 120-240 voltage switch
was
located.
I used a hand reamer to enlarge the rectangular opening so
the fuse holder could be mounted in place of the switch.
You will
probably want to mark the underside of the cover where the AC socket
etc is located so the cover mounting screw holes will line up with the
holes on the front and rear panels of the case each time you put the
cover on while
trial fitting the cover with the 3" fan mounted so it doesn't interfere
with the internal parts.
|

This picture shows where the power supplies are mounted. The small
roundish 5 volt power supply is used to power
the front panel meter. It is mounted to the bottom of the
charger case with the original screw that holds the top and bottom
covers together.
There no mistaking the huge Mean Well 200 volt, 350 ma power supply. It
is bolted to the case with two #4-40 bolts, one at each end with
washers
and
nuts. The case was used for a 450
watt power supply and is a little larger than most cases at 6.125" x
5.875".
The rectangular box near the AC fuse holder is a 12 Vdc, 1.25 Amp
isolated switching power supply that runs the charger and IMA cooling
fans. |

This picture shows the top cover mounted onto the bottom of the case.
The horizontal line near the bottom of the cover is where the top cover
panel is indented and is tucked in behind the lip of the bottom of the
case. You should not mount the Mean Well right up against
that lip
or the top cover won't fit properly.
|

This view shows the left side of the front panel. The socket
on the left of the picture is the discharge socket, The dual
meter is in the middle and the green switch is the mode
switch.. I used hot melt glue to
hold the meter and wires in place. The case metal is so thin
that the normal meter tabs couldn't properly hold the meter tight to
the front panel. Hot glue came to the rescue for that. |

This is the right side of the front panel. The male 4 pin Molex
connector assembly which I sawed off the corner of a junk hard drive is
hidden under all the wires!
D1 and R1 are connect directly to the high voltage pins of
the
charging harness socket. This eliminated the terminal strip.
The small 2 pin male-female connector is the 12 Vdc to
the cooling fan. The 12 Vdc power supply is partially visible to the right of the Mean Well power supply. The 12
volt supply is held
to the
bottom of the case by two #4-40 screws. Be careful and do not
run the screws into any of the power supply components.
|

This is a close up of the 4 pin Molex socket showing where D1 and R1
(see the
schematic) are mounted. This eliminates the terminal strip
that V1 of the charger used.
The curved white 2 conductor wire goes from the 12 Vdc switching type
power supply to the 12 Vdc fan +/- pins of
the charging
harness socket.
The socket is mounted on a piece of the socket mounting metal from the
corner of the hard drive which in turn
is fastened to the front panel with two #4-40 screws. |

|
The
picture to the left shows the small 3" square cooling fan mounted
in place of
the huge original cooling fan opening. The original fan was
so thick
that it wouldn't allow the top cover to be properly mounted to the
bottom of the case because of the height of the Mean Well power supply
underneath the fan..
You
will have to check the clearance between the fan and fuse holder when
mounting the fan.
I have found that the charger power supplies run at the ambient cabin
temperature
while charging the battery and there is more than enough air flow with
the 3" top mounted fan. The fan blows air into the case.
This is a short list of the somewhat unusual tools you will need to
build the charger, a tapered hand reamer, a hand nibbler, a small hand
drill with drill bits and a center
punch. It took me about 38 hours to build the charger. |
|
|
Part designators
D1
F1 (Note 2)
Fan
J1
J2 (Note 4)
M1 (Note 1)
P1
PS1
PS2 (Note 9)
PS3 (Note 9
R1 (Note 2)
SW1, 2
|
Description
Vendor
1N4007, silicon diode 1amp, 1000 V
........................................... Various suppliers (a 1N4004
through 1N4007 may be used)
250 volt, 2 amp fuse and holder
......................................................Various
suppliers, fuse holder bgmicro.com/FUS1008.aspx
3" square 12 Vdc fan
......................................................................
From a computer power supply with a rear mounted fan
Male line cord plug
.........................................................................
Part of power supply case
Molex male 4 pin
............................................................................
Charging connector cut from corner of a HD
Dual red LED meter, 200 volt, 10 amp
........................................... eBay
item, buy a meter with both displays being red
Female 2 pin connector
................................................................... Any
2 pin connector rated for 200 Vdc to match male plug
100-200 volt, 350 ma LED constant current LED power supply
.... Mean Well HLG-60H-C350A from various
distributors or eBay
5 volt cell phone charger
................................................................ eBay item
(To power the dual LED meter) actually 5-30 volt is OK
12 volt, 1.25 amp minimum regulated switching power supply
........
eBay item
(To run the cooling fans) the smaller the better
100K ohm, 1/2 watt resistor
..........................................................
Various
suppliers (Any tolerance value will work)
SPST mini toggle switch
.................................................................
Various eBay suppliers (only 1 switch needed if case has SW2)
Notes:
- There are
many dual
voltage/current meters listed on eBay now, but please, only buy a 4
digit meter that can display 1/10s of a volt.
- I've had
good luck buying parts from B&G
Micro
for many years and you will find most of the small parts on their
website. With luck you may find the resistor and other small
parts on the junk computer supply PCB.
- Use the
case cooling fan connector from the junk computer power supply PCB to
match the one on the fan wires.
- I cut
the Molex 4 pin male connector from a junk hard drive
for the charging connector on the grid charger.
- I used
a male 4 pin Molex female computer power
supply connector on the end of the charging harness.
- I have
found flexible covers for the harness 4 pin Molex female connector on
the
power leads of Dell computer power supplies.
- Instead of
using a dedicated 4 wire cable, you can use four lengths of stranded
AWG 22 (the minimum size wire)
each about four feet long for the charging harness from the IMA battery
connections to the charger. Place the completed harness in
insulated tubing. I found the wire and the split plastic
tubing
at an auto junk yard.
- My charging
cable comes out of a gap at
the bottom of the rear right corner of the IPU case next to the floor
of the car body.
- I used two
small wall warts for the low voltage power supplies. They must
be isolated DC output switching type power supplies.
|
First check
of grid charger
Where possible
I test each power supply
as I get them mounted and wired partially into the circuit. I
use a
normal AC power cord with alligator clips on each lead to temporarily
connect the power supplies to 120 Vac and measure the output voltages
with an external voltmeter.
You can calibrate the charger meter
before it is mounted in the case. And it's easier to
get at the calibration adjustments.
But first, here are a few bits of information:
- In the calibration instructions of the charger
I
will use the
term "DVM" to
indicate a known accurate VOM or DVM for calibrating the charger
voltage
and
current meter. You can also use several meters and average
the readings to calibrate the charger meter.
- While working on the charger it is OK to
disconnect the charger cooling fan. Don't forget the fan
connector is polarized positive and negative so you must connect it
properly to the 12 Vdc supply circuit. I marked the plastic
fan connectors with a red marking pen so I have a quick guide for
connecting the fan correctly. I have found that the
temperature
of the various charger power supplies are basically the ambient
temperature inside the car.
- If the cover is off the grid charger, be aware
that there are exposed 120 Vac connections in addition to the 200 Vdc
connections just waiting to shock the didily out of you. The
charger no load DC voltage is higher than the IMA battery voltage!
So be careful.
- To work on the charger I always set the mode
switch to discharge first and wait until the HV meter shows less than
15 Vdc.
Then I turn the power switch OFF and unplug the AC cord
before sticking my hand(s) into the grid charger.
- R1, the 100K resistor causes the
high voltage to discharge quicker than just the bleeder inside the Mean
Well supply. I found it on a junk power supply PC board.
Return
to top of this file
Calibrating
the multimeter
You will
probably need to check
the accuracy of the charger
multimeter. The meter current calibration pot is labeled IR
and the
voltage calibration pot is labeled VR.
You will need a very small, short flat blade screw
driver to
set the calibration pots. The C350A version of the
Mean Well power supply has an internal constant current adjustment
potentiometer
located under a flexible plug located on the top of the case.
I
found that I did not need to adjust the current output of the supply.
The
first check of the charger meter is done with not having anything
connected to the chargers output connectors.
- Connect the AC power cord
- Set the power switch to ON
- The voltmeter should show close to 200 Vdc and
0.000 ma current with no load on the charger.
At
this point you could calibrate the voltage portion of the meter by
connecting an acurate DVM to the high voltage output of the charger and
adjusting VR pot on the meter to read the same voltage as the
DVM
is showing. To adjust the current pot (IR) you need a load
that
can handle up to 200 Vdc and 350 ma DC. The load needs to be able to
dissipate a maximum of 70 watts. Several choices are
available, a 500 ohm,
100 watt
wire wound resistor, the two bulb dummy load (see
information how to build the load below) or the IMA battery itself.
I origianlly used two 60 watt 115 Vac light bulbs as the discharger load to
calibrate my meter. One builder found
that his Mean Well supply would not output any
voltage or current with the two 60 watt bulb discharger load.
Yet
the charger does charge the IMA battery OK. In that case use two 40 watt bulbs to calibrate the meter current reading. The
Mean Well charger will not output any voltage or current if the load
will present a load that would require less than 100 Vdc within the 350
ma current limiting capability of the supply. Apparently the
supply outputs a test to see if the load (the IMA battery or dummy
load) would result in less than 100 Vdc at 350 ma. If
that combination of voltage/current is detected the supply shuts the
output down until that load is removed or the battery voltage rises
above 100 volts. This will be discused in more detail further down
this article.
When
you turn the Mean Well AC power off after an overload, it resets and will
work properly when switched ON again (no damage done).
I
sometimes use an
aluminum cased 500 ohm, 100 watt wire wound resistor mounted on a large
heat sink with a fan to cool the resistor as the dummy load.
The Mean Well will output 175 volts at 0.350 Adc using the
500
ohm
resistor. This means the charge current will not taper off
when the battery is 100% charged.
The
twin 60 watt light
bulbs dummy load should show ~130 Vdc and 0.350 Adc vs 175 Vdc using
the 500 ohm
resistor. This is because the lit resistance of the bulbs
are not 500 ohms when they
are driven by the 350 ma constant current supply. Old style light
bulbs exhibit a lower resistance when cold vs when they are hot when drawing
current.
You
can also connect the charger temporarily to your IMA battery to
calibrate the dual meter using the procedure listed below.
For a short test you do not need the battery cooling fan
running.
Warning!
Be very careful,
the charger will have
120 Vac AND up to 200 Vdc voltage floating around inside the case waiting to shock you
if you to touch an energized wire
when the power and the mode switch is set to charge. If you
want to play it
safe wear a pair of latex gloves, no metal wrist watch bands etc
Here
is how to calibrate the dual volt/amp meter using the light bulb
discharge load and two external calibrated DVMs.
Temporarily
wire the two DVMs, one to read the discharge load voltage and the other
read the charging current. (Or use one meter and reconnect it
as
necessary to read Vdc or the current.)
- Set the power switch to OFF
- Connect
the two 40 or 60 watt light bulb discharge load to the discharge port of the grid charger with a
DVM meter wired to read the charge voltage or current
- Set the mode switch to Charge
- Set the power switch to ON
- The meter should show ~130 Vdc and ~0.350 Adc
(be careful the bulbs will get pretty hot after a bit) when using two 60 watt bulbs
- If the readings are not close to the DVM values
you will need to adjust the VR and IR pots to calibrate the meter.
My
RL chart
(shown below) was done with a variable high voltage power supply and
two DVMs,
one reading the voltage and the other current. You can use
various combinations of bulbs as the dummy load as long as the combo
will draw 0.350 A. You want to draw as close to 0.350 A as possible because that is
the
current the IMA battery will draw while being charged.
Return to top of
"Calibrating the multimeter"
Return
to top of this file
|
How
to make a discharge load (the dummy load)
The actual discharger I use
consists of two old style light
bubs and two ceramic
light sockets mounted on a short piece of 1" x 6" board. One
socket has a pull chain ON/OFF switch on it. The actual discharge load
is made by using 120 volt light bulbs of various wattage
combinations wired in series. Nothing exotic about that, just wire the
two sockets in series like Christmas tree light bulbs and
attach the 2 wire discharge cable to each of the
single free terminals on each socket.
Before I could wire the ceramic bulb
sockets I had to route out an area
on the board underneath where the sockets would mount with a ~1/2" wide
trench between the sockets for the wires to go between the sockets.
There is another short trench from one socket for
the two wire discharge cable to leave the board. I used a
matching 2 pin male connector on the end of the cable to plug into a 2
pin female connector on the grid charger.
The picture on the left
shows the routed out area underneath where the
sockets mount. The right side picture shows the
sockets mounted on the board.

I used a long
two wire
cord from a vacuum cleaner (with the plug
changed) so I could have the discharger sitting in my closed garage to
have an idea how the discharge is going. Since I took these
pictures I have added two short nails sticking up between the sockets
with one nail wired to the positive lead of the discharge cable and the
other nail connected to the negative lead of the discharge
cable. This allows me to have the discharge load in my garage
with a voltmeter connected to the nails to read the battery voltage
remotely.
A normal VOM won't require any power
for it to continuously display the voltage. I use an old
Simpson
260 VOM for this job. As old as it is it still reads the same as my DVM.
Some people use dual bulb "Y" sockets designed for wall
mounting to make the discharge load. They have two wires on
each socket that can be
wired in series. You don't have to route the board with a "Y"
socket. The problem with the "Y" socket is that there is no switch on
the ones I've seen. I like the remote cut off feature by
having a switch on one of the sockets.
While the battery is being charged the batteries will get very warm so you
MUST run the battery pack cooling fan at the same time.
If you turn the fan off after charging the
battery temperature will continue
to rise for many hours due to the stored heat IN
the cells in warm weather. The cooling fans run any time the charger is switched to ON.
If
you want to get fancy you could even have a current meter setup at the
dummy load to read the current by connecting an amp meter
correctly in series with one lead of the discharge load cable.
Return to top of
"How to make a discharge load"
Return
to top of this file
Current vs
light bulb wattage at various battery voltages

Click on the chart to see it full
size.
I did bench tests on
various wattage incandescent light
bulbs to help understand the current vs voltage change. I also checked
the
current flow using my 500 ohm, 100 watt resistor for comparison. The
data is presented on the chart above. Use this chart as a guide to what
wattage bulbs to use depending upon what current you want to discharge
the battery at.
While using a resistor as a discharge load will work; you do have to
take into consideration that the resistor will be dissipating up to 60
watts when starting the discharge with a fully charged pack. Even
mounting an aluminum cased 100 watt resistor on a 3" x
5" finned heat sink did not keep it cool enough so it wouldn't cook my
finger if I touched it. A computer fan did not help
much. As a test I finally used a microprocessor dual heat
pipe heat sink with a large shrouded fan to be able to keep my fingers
on the resistor for a short
time.
If you use light bulbs I recommend using two bulbs wired in
series to do a
discharge. If you use one 120 Vac light bulb it
will
greatly shorten the bulbs life if you start discharging from a battery
voltage higher than 120 volts. If the bulb blows out due to
the
high voltage you will waste time if you aren't around to monitor the
discharge. As it is, a two cycle rejuvenation is going to
take days to accomplish. You don't need another day added to the task
if a bulb blows.
You will have
to wire up an external current meter to check the actual
discharge current and perhaps use different size bulbs in various
combination to get the current you want at the beginning or end of the
discharge. Personally I use two 40 watt bulbs and when the
voltage gets below 20 volts I replace one of the bulbs with a shorted
screw in adapter to raise the current up a bit.
Old fashioned incandescent light bulbs are getting hard to find and CFL
bulbs will NOT work. Halogen flood lights work fine and have
the same curved discharge current vs voltage as the normal old
fashioned bulbs.
Return to top of
"Discharge vs light bulbs"
Return
to top of this file
Information
about rejuvenating a battery
First off
you might ask, "Why even discharge the IMA battery?" That is
a good question.
In use, the individual cells of the IMA battery will tend to
deteriorate over time and the cells will have different levels of watt
hour capacity. This is called an "unbalanced battery". When
driving the car, the weaker cells limit the time and amount of assist
the battery pack can deliver. Just like a steel chain, the
weakest link (the weakest cell in our case) determines how strong the
chain is. This due to the 120 cells being wired in series
like
Christmas tree lights.
The batteries can usually be brought back to usable capacity by
properly grid charging them. This is called "balancing the
battery", "a balancing charge" [or actually] "a trickle
charge". New batteries ought to be
grid
charged three or four times a year after the first 6 months to a year
of use. Think of it as a maintenance chore to keep the
battery
pack balanced over time. This will extend the life of the
battery. My Honda warranty IMA battery was replaced in Jan 2013
and is still going, not like new but for the way I drive, it does work
OK.
The purpose of discharging the battery for a rejuvenation is to
discharge all the cells down to a fairly low or even zero voltage. This
causes
chemical reactions within the cells which in turn will cause the weak
cells to be in a condition to gain capacity while being charged again.
Discharges to only 100 volts etc just isn't enough to do much
rejuvenation of the cells.
Unfortunately when discharging an unbalanced battery pack the weak
cells will discharge to 0.9 volts (the rated "discharged" voltage
condition) much quicker than the good cells. Even when the
battery pack reads a little below 144 volts some of the week cells
could
already be fully discharged. Typically the weak cells will not
only
discharge to 0 volts but they will be slightly "reversed charged" by
the discharge current while the good cells in the pack continue being
discharged.
High discharge current of reversed charged cells is not good!
Using too high a discharge current with cells reversed charged can
result in those cells overheating with possible venting and even
leaking which will cause all sorts of problems over time. It
has
been found that 0.350 A (ampere) discharge current is a safe current to
start the discharge.
To rejuvenate a battery you should do 1 or 2 charge/discharge cycles
with a final grid charge. The first cycle starts with a 0.350
A
charge of 24 to 35 hours to fully charge the battery to ~174 volts,
followed by a discharge to a desired low voltage.
Different discharge cutoff voltages have been put forward by members of
the insightcentral.net/forums.
I normally discharge to 10 to 15 volts. There is a technical
paper by Robert
Huggins here (see pages 226 to 233) that indicates that there
is some merit to this approach. By experimentation, Insight
Central members have found this procedure does work.
Recently tests have been done by forum members that completely
discharge the battery pack to zero volts. I allowed my last
discharge to go to zero volts by leaving the discharge load on the
battery overnight. After my usual one cycle charge after the
discharge the battery is performing better than a discharge stopping at
~12 volts. It has also been
found
that batteries that have sat unused for many years and have self
discharged to very low voltages were brought back to life by doing
several rejuvenation charge/discharge cycles. Individual
sticks
of 6 cells that were in very weak condition were also brought back to
life after sitting for long periods of time.
I recently found an Insight that had sat outdoors for 10 years not
being driven or run. The car is in sad condition. I
was
allowed to take the battery out of the car to attempt to rejuvenate
it. The complete battery pack measured 0.8 of a volt before I
did
anything to it! After two rejuvenation charge-discharge
cycles to
15 volts followed by a final grid charge the pack sticks were very well
balanced. Unfortunately the car isn't in running condition to
drive it on the road to test the battery.
There is no danger of a cell becoming reverse charged by
allowing
a battery pack to self discharge for a long time with no load on
it. Ni-MH batteries self discharge roughly about 1% per DAY.
Damage can occur by improperly charging
a dead battery when starting to use it again.
If
you find a car that has sat for many months or several years without
running it is recommended that a slow grid charge be done before using
the IMA battery again. In other words, don't just start the car and
take off on a long trip home with it. The cars normal
charging
current has much too high a current level to do a proper balancing or
re-forming of the battery. A discharged battery caused by
sitting
unused is a great candidate for a rejuvenation though, so don't loose
that opportunity by letting the car charge the battery. And it is
a great bargining chip if you are contemplating buying an Insight with
a "shot" battery. :-)
If you have a short trip you can switch the IMA battery master switch
to OFF, start the car on the 12 volt battery that has been charged and
drive the car home. An error light will light up on the
dashboard, this is normal.
The switch is located under a small cover on the top of the battery box
(IPU) at the rear of the car under the rear carpet. You will need a 10
mm wrench to remove the small cover. There is a red safety
clip
over the handle of the battery disconnect switch that needs to be
lifted off the handle so you can switch it OFF. Replace the
clip
so you don't loose it.
CAUTION:
With the IMA battery switched OFF the 12 volt battery will NOT be
charged, so the distance you can drive is limited by how long the 12
volt battery can supply enough voltage to run the gas engine.
It is possible to open the IPU battery case and disconnect the two
connectors towards the front of the car on the Battery Control Module
(BCM) case and
safely run the car as a gas only car for as long as you want
to.
The 12 volt battery will be charged and some people have run their
Insight for years that way. Instructions how to disconnect the IMA
battery can be found at insightcentral.net/forums/
Google
"disconnect battery" on the forum.
Please note that the car will have a much slower acceleration rate at
low engine speeds with the IMA battery not being used. The gas engine
is tuned so it has to be revved up to develop its peak power (torque)
at ~4500 RPM. Normally the IMA system (electric motor) fills
in
at the low RPM of the gas engine. You will get normal high
mpg
numbers once you are cruising along.
Finally, as they say in some TV advertisements, "But first .........."
If you have installed one or two diodes in the high voltage charging
harness you will NOT be able to read the battery voltage or discharge
the battery. You must remove any diodes in the HV lead(s) of the
charging
harness. The diode(s) to remove are not inside the charger, but on the connecting harness
from the charger to the battery itself.
Return
to top of "Information about rejuvenating a battery"
Return
to top of this file
|
|
Hints to help you use the
grid charger
The
method I
use to have an idea when it's time to stop the discharge is to record
the battery voltage at the start and at each hour thereafter as the
voltage drops to the voltage were you want to stop the discharge at.
You will find the volts per hour change will
start at 4 to 6 volts per hr and will taper off to below 0.5 volt per
hour.
A weak battery may drop from 115 to 100
volts very quickly as cells drop out and become reverse charged. This
is normal. With a low current discharge the cells shouldn't
be damaged with the cooling fan running.
By recording the volts per hour change as the battery goes below 115
volts you can guesstimate how weak the battery is. A quick
voltage drop of 1 volt in 5 or 10 minutes is a sign of a weak cell(s)
becoming completely discharged. Pay close attention to the
battery voltage at that point if you are not discharging to zero volts.
After you terminate a discharge by disconnecting the load, the battery voltage will rise up to
some higher voltage rather quickly.
A weak battery discharged below 100 volts will typically rise
back to 120 volts or more. A really good battery will not
rise as much. It is permissible to start the discharge again to pull
the battery back down to the final goal voltage but keep an eye on the
voltage because it will drop to your desired cutoff voltage quicker
compared to the initial discharge.
When charging the battery, the high cut off voltage should top out at
~174 volts for a battery in good condition. The exact voltage
will vary depending upon the battery temperature and charge
current. A warm battery will have a lower voltage than a cool
battery at the same point in a charge cycle.
A weak battery may show higher than 175 volts due to
higher than normal internal resistance (IR) of the cells. The
higher the charge current, the higher IR voltage drop which will cause
the total battery voltage to appear higher while charging. As
you can see there are a lot of variables when working with a 120 cells
connected
in series.
By watching the charge voltage change per hour you will see that the
voltage increase rate per hour decreases with time. My old V1
grid charger with a 265 ma
charge rate started at 4 to 6 volts rise per hour and
then tapered off to ~0.2 volt per hour after the voltage was above 170
volts. At that point the cells of the battery that
are are 100% charged will be producing a lot of heat. So it is
important to not turn the cooling fan off while charging or discharging.
The typical charge time for a good battery is 24 hours to 35 hours.
The
discharge time varies greatly and is determined by how good the battery
is etc. A complete rejuvenation is going to take days to
complete. But if you can get a year or more life out
of a
weak battery it might be worth it.
The money you save on gas can pay for a new (better than OEM) battery
from one of the forum vendors. One Insight owner
posted that he not only paid for the new battery by grid charging (in
the gas savings as compared to his other vehicle) but for
the Insight too!
Return to top of "Hints to help you
use the grid charger"
Return
to top of this file
|
Do a
rejuvenation (Finally)
The basic
procedure to do a rejuvenation is as follows, the battery should first
be grid charged to 100% state of charge (SOC) 174 Vdc to
balance the
cells
as much as possible, then slowly discharge the battery, then charge it
again.
That is considered to be one rejuvenation cycle. Really
weak batteries respond better to doing the
charge/discharge/charge sequence 2 or even 3 times in a row. One
sequence will take several days to complete. And with simple
grid
charger/discharges you need to monitor the voltage to turn the charge
or discharge off.
Various
cutoff voltages of the discharge are recommended by different
sources.
I typically discharge my battery in one long discharge to below 15 Vdc
starting the discharge at 0.350
A. A full discharge can take many hours depending
upon the
condition of the battery and the discharge current. As the
battery voltage goes down you will have to change to higher wattage
bulbs to keep the discharge current at 100 to 250 ma.
As
the battery pack is discharging the weaker cells will discharge quicker
and will actually suddenly start being reversed charged by the current
caused by the rest of the battery pack. Through
experimentation
on the InsightCentral
forum it has been found that if the cells are reversed charged at a
low current (typically no more than 350 ma), that no damage
will
occur to the cells..
When the battery discharges to the voltage you want, set the dicharge
load switch to OFF. The battery voltage
will rise to above 100 volts
rather quickly. This is normal. and you need to allow it
to happen. My battery voltage normally bounces
back to 120 volts or so in less than 30 minutes after removing the
discharge load.
If the voltage doesn't rise above 100 volts after waiting awhile, this
could indicate your battery is really sick.
Here's why you need to wait until the battery is above 100 volts:
The Mean Well power supply will not
charge the battery if it is below 100 volts because a protection mode
called "Hiccup mode" kicks in. The charger will power back up when the
voltage rises to more than 100 volts by switching the charger OFF and then back ON again..
If you are trying to rejuvenate a battery that sat for many years and is below 100 volts, go to Charge dead battery to >100 volts which is located below this article for information how to charge the battery to 100+ volts. I usually let the battery rest for an hour with the IMA fan running to
dissipate some of the battery heat before starting the next charge
cycle. I also try to start the charge in
the early evening so it runs when the ambient temperature is below 86°
F. Here in South Florida I normally don't have to worry about
the temperature being too cool. 60° is cold to us!
The method I
use to have an idea when it's time to stop the discharge is to record
the battery voltage at the start and at each hour thereafter as the
voltage drops to the voltage were you want to stop the discharge at.
You will find the volts per hour change will
start at 4 to 6 volts per hr and will later taper off to below 0.5 volt
per
hour.
A weak battery may drop from 115 to 100
volts very quickly as cells drop out and become reverse charged. This
is normal. With a low current discharge the cells shouldn't
be damaged with the cooling fan running.
By recording the volts per hour change as the battery goes below 115
volts you can guesstimate how weak the battery is. A quick
voltage drop of 1 volt in 5 or 10 minutes is a sign of a low capacity
cell(s)
becoming completely discharged. Pay close attention to the
battery voltage at that point if you are not discharging to zero volts.
After you terminate a discharge the battery voltage will rise up to
some higher voltage rather quickly with the load disconnected.
A weak battery discharged below 100 volts will typically rise
back to 110 volts or more. It is permissible to start the
discharge again to pull
the battery back down to the final goal voltage but keep an eye on the
voltage because it will drop to your desired cutoff voltage quicker
compared to the initial discharge.
When charging the battery, the high cut off voltage should top out
at
~174 volts for a battery in good condition. The exact voltage
will vary depending upon the battery temperature and charge
current. A warm battery will have a lower voltage than a cool
battery at the same SOC in a charge cycle. When the battery
is
nearly full charged it is not unusual to see the voltage start going
down as the battery gets warmer and warmer. This drop in
temperature is not always the 100% charged point.
A weak battery may show higher than 175 volts due to
higher than normal internal resistance (IR) of the cells. The
higher the charge current, the higher IR voltage drop. This will
cause
the total battery voltage to appear higher while charging. As
you can see there are a lot of variables when working with a 120 cells
connected
in series.
By watching the charge voltage change per hour you will see that the
voltage increase rate per hour decreases with time. My old V1
grid charger with a 265 ma
charge rate started at 4 to 6 volts rise per hour and
then tapered off to ~0.2 volt per hour when the voltage was above 170
volts. At that point the cells of the battery that
are at 100% charged will be producing a lot of heat. So it is
important to not turn the cooling fan off while charging or discharging.
The typical charge time for a good battery is 24 hours to 35 hours.
The
discharge time varies greatly and is determined by how good the battery
is etc. A complete rejuvenation is going to take days to
complete. But if you can get a year or more life out
of a
weak battery it might be worth it.
The money you save on gas can pay for a new (better than OEM) battery
from one of the forum vendors. One Insight owner
posted that he not only paid for the new battery with the gas savings
compared to his other vehicle, but for
the Insight too!
Return to top of "Do a
rejuvenation"Return
to top of this file
|
Charge dead battery to >100 voltsNote: If you just discharged the battery to below, 100 volts just disconnect the load and the battery will
quickly rise above 100 volts within an hour. The Mean Well power supply will not
charge the battery if it is below 100 volts because a protection mode
called "Hiccup mode" kicks in. The charger will power back up when the
voltage rises to more than 100 volts by switching the charger OFF for a few seconds and then back ON again.. What
this means is if your battery has sat around unused for a long enough
time that the total pack voltage is below 100 volts you will have to charge into the battery to raise the pack voltage a
little above 100 volts at a charge rate of 350 ma or less. If
the battery pack is below 12 volts I would recommend that you use
either a variable low voltage DC supply or a normal 12 volt battery
charger to wake the battery up. By using a variable 12 volt power
supply I could keep the charge current to 100 ma by slowly
adjusting the voltage higher or lower over about a 1 hour time. If
using a 12 volt battery charger, I would wire a normal low wattage 12
volt car light bulb (for instance a Philips #1895, 12v, 3.8 watt
bulb) in series with the positive lead of the charger to limit the
charge current to wake the IMA battery up. Don't use a stop light or
headlight bulb. They will pass way too much current through a less than
12 volt battery pack. The bulb should light up fairly bright at
the beginning of the wake up period and get dimmer as the IMA battery
comes up to 12 volts. Even a regulated, low current 12 volt
phone charger might work without a bulb. Naturally be aware of the
polarity of the connections. Once the battery comes up to near 12
volts I would remove the series bulb and connect the 12 volt charger directly
to the IMA battery for another hour. There are chemical reactions going
on at even that low per cell voltage. Now
that battery is awake again, here's a way to
allow you to get the IMA battery above 100 volts. Build
the discharger load and install two 40 watt bulbs in the sockets.
Using a VOM or DVM you should see about 60 ohms at the cable end
of the discharger harness when the bulbs are cold. Set the switch
on the discharger load to OFF Follow these steps to start charging the battery to above 100 volts: 1. Set the IMA battery master switch to OFF 2.
Temporarily wire the discharger in series with the positive lead of the
charging harness to the normal battery positive connection point at the
battery. The negative charger lead should be connected directly to
the
normal negative lead connection point at the battery 3. Set the grid charger Mode switch to discharge 4. Set the IMA battery switch to ON 5.
Set the gridcharger AC switch to ON, after a moment you should see the
IMA battery voltage of about 12 volts showing on the charger voltmeter
but no current flowing 6. Set the gridcharger Mode switch to Charge,
wait till you see ~200 volts on the meter (the Mean Well has to go
through some self tests before outputing high voltage) 7. Set the discharger load switch to ON, you should see the bulbs light and charging current on the meter 8. Use
a seperate meter to read the actual battery voltage since the charger
meter wont be showing the true battery voltage with the series discharger load
connected. Allow the charge to continue until the battery shows ~105 or so volts.
When
the battery has been charged above 100 volts do the following steps: 1. Turn the charger OFF 2. Switch the IMA battery master switch to OFF 3. Wait 30 seconds or more for the charger and battery voltages to drop to zero volts 4. Disconnect the discharger load from the charging harness 5. Reconnect the positive lead of the charging harness to the battery lead connection point. 6. Set the IMA battery master switch to ON.
You can now give the
battery a normal grid charge to 174 volts at 350ma with the cooling fans running etc.. I would definitely read and record the stick
voltages after waiting an hour or so after each charge to see how
balanced the sticks are. Return to top of "Charge dead battery to >100 volts"
|
|