Rebuilding a Gen 1 battery

You need to remove the bus bars, compression bolts, and unbolt the modules from the bottom of the case. There is an excellent discussion here:

http://priuschat.com/forums/generation-1-prius-discussion/84017-nhw11-traction-battery-autopsy.html

 

Yes, the ones that are more than 1.2V less than the top modules have a dead cell and need to be replaced. You don't necessarily have to pay attention to + and -, unless you are using an analog meter -- a digital meter will show e.g. -7.90V if measuring the other way. Wow, 5 modules! Am I remembering correctly, you just acquired this car? I'll bet that the prior owner has been regularly resetting the check engine light for a while to have that many gone bad.

 

7.9 is good. A range of 7.90 +/- 0.05V after a week is very good. It would take several months of sitting idle for them to fall below 7.2V. Those should last for a while.

 

It is hard to say, and depends on what you mean by "used". A fully reconditioned battery, one where the NiMH voltage depression has been resolved, will have matched capacity and internal resistance -- basically what Healdsburg Ted and ReInvolt do -- only brand new cells would be better. A used battery from a salvage yard will have had nothing done. Your own repair will land somewhere in between. People that have repaired their batteries taking the route that you are usually do not write back with a subsequent complaint, so it is likely to give you at least a good year of service, possibly several.

 

Measuring cells at rest won't be conclusive. Ideally you need to measure voltages under load/discharge....and try and charge all slices up to the same level.

If the car is still drivable, the best way to measure load is to drive the car in reverse uphill with Techstream attached...you can watch all 19 cellblock measurement points in realtime. You could also configure a scanguage to show much of this data via Xgauges, but you can only see 4 data points at a time.

Reverse is best since the ICE will not be involved in propelling the car (reverse is 100% electric), and going uphill in reverse is even better since it puts more load on the batteries.

 

It is too late now, but if I was doing this, I would have force-Charged the entire battery pack first, perhaps 2-3 times. The computerized systems maintaining the proper charge on the battery pack does a superb job at equalizing the battery packs. After this, I would then look at the voltage on the individual batteries. It appears as tho the previous owner was never concerned about the HV pack. Anyway Good Luck :cheer2:

 

My Gen II replacement of a few modules has been working fine. That was over 3000 miles ago.

 

I've not yet tried this on a Prius, not even sure it is possible when the car has coded a battery fault, but it does work, to an extent, on Honda. However, it truly only postpones the inevitable. When my stepfather got the IMA light in his 05 Civic, I had him disconnect and reconnect the 12V battery. That automatically triggers a negative recal -- a force charge. I then had him be very light on the throttle, to minimize battery demand. He got the light one more time, due to having cruise control on when encountering a hill. He had a bad module (stick, or subpack, as is known in Honda parlance), which I swapped out and did charge reconditioning on the rest. That was 8 months ago.

 

I do agree with your first sentence, that is a unknown. There is some advice about not force-charging, but I have done it several times now with no harm. I do pick a situation where I think it may be necessary. Recently I left the car in the garage for three months while I was in Europe and before leaving I charged the 12 volt separately, force-charged the HV Pack and then disconnected the 12V negative lead. No problems at all when I returned. Another situation that many Prius owners observe is charging up a steep hill at 65+ and experience overheating and inverter problems, that would also call for forcecharging, after cooldown and taking the hill at a more moderate speed. If I was to experience HV problems, the first thing I would try is force-charging and then cleaning all the busbars and connectors, probably noting voltage levels also on the individual packs. I was also warned earlier on letting the car glide in neutral and now I see that one of our clever hobbyist did a extensive study on the parameter differences of stealth and glide. The differences were tiny! There is a lot of scare tactic going on at this site, probably by the uninformed. This was especially true in the beginning, now I have noticed that most of this fear mongering is disappearing. Sorry I rambled on so much. Andy

 

I used a pair of these gloves:

Electrical Gloves - 1000 Volt Electrical Rubber Gloves

Only time I used them was to remove the terminal nuts and bus bars.

Mylar

 

You can try charging individual slices, but you need an appropriate NiMH charger. You should also measure capacity (usable amp hours) and internal resistance of each slice.

You need to rebuild the pack with cells similar capacity and internal resistance...otherwise you will be chasing your tail for weeks. Testing slices at rest will not tell you much.