Gen II Prius Individual Battery Module Replacement

In my case I think the problem was in ECU software, as I told already before i updated it but too late... In documentation of ECU software said that the new software prevent HV battery from overheating...

"CP-0028L-0511" that's the name of documentation, if you google it you will see .pdf

I always driven with AC

 

If you follow the instructions on page 20 of the manual the charge input calculation goes even further than my recommendation.
The calculation is battery capacity in mah divided by the charge current in amps divided by 11.9 to give the charge time in minutes.
Divide the charge time in minutes by 60 to give hours and multiply the charge current in mah would give:-

6500mah / 2 / 11.9 = 273 minutes / 60 X 2000mah = 9103 mah charge input.

This would represent a charge input efficiency of 71% well in line with accepted figures.

John (Britprius)

 

I can only find that documentation relating to the Lexus GS450H.

John (Britprius)

 

John, I told that 2 pages before that I have Lexus GS 450h
It have 40 modules pack, same modules like in Prius 2 Gen.


Now charging the #7 module for second time and at 4000mah of charge the charger already shows 8.8v on module, looks like it's already full...

 

Sorry for the confusion, but being in the gen2 Prius section it is easy to forget. (senior moment)
A voltage of 8.8 volts on a 6 cell module may not be full voltage, "not far off" but voltage on it's own does not tell the state of charge or balance. As you probably realize it is only discharge figures that give the capacity. The charge input depends on the efficiency of the cells to accept the charge, and many things can vary this.
I would continue the charge of this cycle, and check the discharge capacity to see if there is any improvement.

John (Britprius)

 

That's the results until now, very small improvement, now will do all other modules 3 cycles and after will continue more cycles to all modules until they stop improving

#1 D3200 C8000 D4498 C8000 D4742 C9100 D4908
#3 D2400 C6866 D3595 C8000 D3719 C9100 D3844
#5 D2400 C6700 D3459 C8000 D3700 C9100 D3983
#7 D2000 C7100 D3110 C8000 D3146 C9100 D3277

since i doing now manually and can't set discharge after charge immediately some times between charge discharge have a pause 1-8 hours...

also noticed after discharge to 6V modules almost immediately going to 6.3V and after continues rising but very slowly, the module #7 discharged at 3277mAh about a hour later i tried to discharge it again to 6V and got 87mAh extra, that's normall or should i discharge them lower in this case?

Thank you.

 

A small recovery of voltage and capacity is normal after standing for a while after discharge.
The capacities you are reaching of close to 4 ah "although not high" are enough to run the car with good economy figures.
I know you are averse to taking the discharge to a lower voltage, but do try going down to 0.9 volts per cell (5.4 volts per module) on one module. If they cannot be taken to that level they will not function any way. Taking one that bit lower may show if there is anything to be gained capacity wise by taking them lower.

John (Britprius)

 

For parallel charging what is the voltage and amp do you selected?

 

NiMH must not be charged when connected in parallel. Just charge the whole pack in series.
Parallel "equalisation" is waste of time.

 

Can you expand on this? I have found parallel "equalisation" use full. One example would be to bring a matched group of 28 modules to the same voltage before assembly into a pack. Also before load or capacity testing it helps if all modules are at the same voltage.
Brad

 

Kiwi is a skeptic on balancing modules. He argues that you can't extend the life of the HV batteries by these methods. I and several others respectfully disagree.

JeffD

 

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I feel we are missing something here. If your modules are all reaching 7.8 volts at full charge this is well bellow the expected full charge voltage of around 8.4 volts , and this could be where your apparent capacity loss is. Full charge NmHi cell voltage is typically 1.41 volts to 1.48 volts
Are you sure the charger is not shutting off early.

John (Britprius)

 

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Thankyou for clearing the issue. The voltage difference of 0.2 volts could be down to voltage drop in the charging leads or a poorly calibrated charger or meter.
Is the charger using a mains supply or some other low voltage DC supply? Perhaps clutching at straws, but something seems odd. I can understand having some poor modules, but a pattern of decreasing capacity seems wrong.
Can you jump a few modules? "out of sequence" to see if the trend continues steadily or as predicted takes a big fall.

John (Britprius)

 

The rapid discharge to ~7.9 is the dissipation of the "Surface Charge" and is normal.

Buyer beware

You are seeing the voltage drop in the charging leads of the charger.

Did you clamp the sides of the module while charging? They will bulge if you don't due to heating. Once that happens, you have a new bad module.

JeffD

 

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Thanks Brad for you question....Expanding on something which I deem to be waste of time is another waste of my time. I have created extremely simple and efficient ways of testing, charging and discharging the packs. This month I am aiming to reduce the overall cycle to less than 3 hours (2 full-pack charge cycles and 1 discharge cycle) from currently 6 hours. No need for me to go "parallel", or "sideways" or "perpendicular". I am going straight forward - that is what I do. There will always be other so called "experts", watch this

 

Roy from Canada -- Kiwi - your answer is of no help to Brad and is not in the spirit of helping him understand why paralleling the batteries is not of any use. Your answer implies that their is no need for an answer and your equipment is his only solution.

In that respect you are a very poor teacher and can be of little help to people who access this site as they will feel belittled from your answers.

To Brad:

Paralleling the batteries will bring them to the same voltage but not to the same capacity. Some of your batteries may have a high capacity and others a low capacity. When these batteries are placed in series( as they are when assembled and in the car) they will react differently to load currents placed on them when the car is running and their output voltages will be different. The prius car looks at these batteries in pair modules, if one pair differs in voltage from others the computer picks this up and may give the triangle of death if the difference is great enough.

Your paralleling of the batteries initially will make the computer think that everything is OK - before loading begins( this assumes you have just installed the batteries in the case and reinstalled it in the car). As soon as the car requires high current from the battery(like going up a steep hill) the weak batteries will lower their voltage more then the strong ones and cause the triangle of death if the difference is great enough. This is why it is best to have the capacity( ie the discharge capacity you measure when cycling the battery module) to be close to the same for all batteries in the pack.

Paralleling the batteries can not give them that same capacity. Even if all the batteries are weak. but have the same capacity, the computer will not object and call up the triangle of death.

Hope this helps

Roy