What Are your cell voltage's? here are mine!

Thanks for taking the time and effort to measure the cells. Just curious, are you using a Fluke 113 or similar industrial electrical tester, with appropriate safety approvals?

It's not so much the voltage that can be dangerous. DC systems have extremely high short-circuit current capacity

 

You can get this with a scantool, too, and have a nice printout,
without going near the HV yourself. Well, if the voltage-sense
modules in the battery ECU are to be considered accurate, that is..
.
The real trick is to compare them all under various loads, like
heavy discharge pushing the car or charging by force-charge or
regen. How far they all *deviate* relative to each other is
the real acid test. [or in this case maybe it's the base test]
.
_H*

 

Would you please tell us the charge or discharge current value?
If it was under no current (open circuit), I believe the voltage values mean nothing.
(A dead module voltage can be seen 7.2V value.)

Following data is taken by Japanese friend's dealer using Toyota factory scanner.
The discharge current was 1.56A, and the each pair of module voltage values are shown.

Ken@Japan

 

No, but the Toyota scanner does.

The pictures don't show any dead batteries.
The friend's battery is very healthy, 0.0% delta-SOC.

Ken@Japan

 

See? I always knew you had a wicked sense of humor

 

No, I believe he means that you may not be able to tell the difference between a live cell and a dead cell unless they are under load.

 

OK FWD, you have piqued my interest. I am assuming that you took the cover off the HV battery and measured across each cell for the voltage value displayed??? Or do you have some neat trick to access status info.. I understand the reasoning to monitor the cells, I am just curious how you did it. If you had to disassemble the pack did you add any sort of plug to facilitate easier voltage reading next time around. While you (and if you were) were inside, did individual cell replacement seem possible, if a cell were to go bad?

Keep Posting and thanks de Pat KK6PD

 

Thank you for your comments. That's exactly what I meant.

Flying White Dutchman,
I would like to suggest you to learn the basic NiMH chemistry.

Ken@Japan

 

Thank you for your data.
It's interesting the voltage on the odd number of modules are always odd(low).
Do you know why?

Ken@Japan

 

FWD, please explain precisely how you are measuring the module voltages, and what instrumentation you are using.

Is it possible that some weirdness in the measurement technique results in the unusual pattern that you charted in post #14?

 

Toyota wants what?
Do you believe Toyota can control the even number of module volage high and odd one to be low?

How did you measure these?
My assumtion is you did small number first then went through high numbers, then these voltages were dropped as you consumed the battery power.
Maybe, you did not change polarity of your instrumentation, so your readings were some thing like...
#1=+7.91V, #2=-7.96V, #3=+7.92, #4=-7.96V and so on.

Ken@Japan

 

Hi FWD,

Since your chart shows an unusual result, this causes me to speculate that a measurement "artifact" is responsible. I assume that the battery ECU sense wires are still connected to the 14 module pairs while you perform your voltage test, is this correct?

If the multimeter test lead polarity is switching from + to - then - to + as you move from one module to the next so that you are obtaining alternating positive then negative voltage readings, then the combination of the multimeter's impedance plus the battery ECU voltage sensing circuitry might result in the weird result that you obtained.

As you pointed out, the difference between high and low voltages is only 0.06V on a base of ~8V. You are measuring percentage changes of 0.75% or less. Any differences in impedance presented by the multimeter and sense circuitry combination might contribute to the 0.06V change.

Better to keep the multimeter test lead polarity the same as you are measuring each module so that if the multimeter's impedance changes slightly when measuring positive vs. negative voltages, that will not contribute to measurement error as you measure each module.