Gen II Prius Individual Battery Module Replacement

Great way to look at it!

 

So... I ran charge cycles back to back untill I hit 7000mah. Basically the charger kept peaking out at anywhere from 500 to 2000mah. Ran the first discharge on them and the numbers got worse

1. 1341
2. 1476
3. 1132
4. 1307

Of course we were in the high teens before this. So im going back to run 3 cycles and let the charger do what it does. But to get anywhere it looks like im gonna be running like 10 cycles or somewhere thereabouts. Is this ok to do? Is it too much stress on the modules? Im guessing it will likely shorten their useable life by a bit. But maybe these mods are just plain wore out anyway. Whats a reasonable discharge mah number, I know people like to see 6000. But if I can get these to 4000? Just worse fuel economy right? Anyhow any input would be greatly appreciated. Thanks in advance!

 

I hate to say it but the more I'm hearing the more I think these modules are just headed for the recycle bin. If you need to keep restarting the cycle on a manual program (unless something isn't set right), the fact you have trouble getting it to inject the full 7000 mAh requested and that you're getting less capacity each time, it sounds like the charger is telling you the modules are not likely to be revived to any reasonable/usable capacity.

You are right you could use degraded modules and put them back into service anyway. The issue is that even if you could get your modules back to 3000 mAh capacity I think you'd still be better off investing in finding some good battery modules for rebuilding primarily because you'd more than save that money at the gas pump from improved fuel economy. If I were taking the time to rebuild the lowest number I would accept for a module would be around 5000 mAh (I would use 6000 mAh for my own vehicles) and they should all be within 500 mAh of each other across the whole pack (ie if your min is 5000 mAh, then all modules should be between 5000-5500 mAh) and highs/lows matched together in order to prevent issues with "weak bank" codes.

I wish I had better news for you but you should be able to pick up an later model Prius (or Camry hybrid as they use the same modules but there's 34 so you'd have to buy some spares since a 1st gen Prius needs 38 vs just 28 needed in the 2nd gen Prius) pack for a fairly reasonable amount and cycle those for rebuilding your pack. Hopefully someone else can comment on retrofitting issues (if any) on using gen 2 and gen 3 modules in a gen 1 Prius. To me the most important thing to look for if you're going to look at junkyard packs is when they were taken out of service (I'd want one no more than about 6 months out of the vehicle unless they allowed you to test it before buying, but usually they don't). Ideally you'd also find a pack that lived most of it's life in colder weather (northern US and Canada) but that's not always an option either.

 

Yeah, I agree, these modules seem shot. At this point I would recommend doing what scotman27 did with his Gen 1. I'm guessing you've seen his thread and his pack turned out great.

 

X2

Your chargers won't go to waste checking the new modules and you'll have a good rebuilt pack in the end that should last you a very long time.

got some young 2012 modules | PriusChat

 

Yeah I wish I had the means to collect 38 modules of a later generation at a reasonable price. Seems like the junkyards are getting wise. Probably due to rebuilders buying them all up. I have located a pack at a good price that is tested as a good pack with a guarantee to this effect. Was pulled from a car that was pulling no error codes etc... should be here Tuesday or Wednesday. So hopefully this pack will be worth balancing etc... no core charge either so ill have my pack to experiment with and find any good cells to recoup some money hopefully.

 

Update: the junkyard pack showed, and was DOA. threw codes upon install and pulled it out, about 10 modules were low voltage. So im taking one good module for now, from the junkyard pack to replace the one bad module in mine. The car was driveable with my pack, just pulling codes. Found a refurbished pack for 800 and probably gonna go for it, was refunded on the junkyard pack and they dont even want it back. So I have 2 cores now. 3 weeks of down time, 2 bad packs... the $800 or $1200 options are awfully tempting. 800 being a 90 day warranty, 1200 being 1 year. Or of course 1600 for the gen 2 module pack. Mulling it all over now, but man this sure was more than I expected in the pita department!

 

Too bad the junkyard doesn't quantify the packs ahead of time. Guess it must not be worth it to them.

XT1049 ?

 

Key here IMHO is how long were the other packs out of the vehicle. I think most junkyards don't think about these traction batteries as wasting assets (esp if you don't maintain them in the proper voltage range). The junkyards are usually just focused on how many miles the vehicle had when the pack was pulled and then assume it must be worth a certain amount based on the list price for a brand new part at the dealer no matter how long it has sat on the shelf. Obviously we know better but the key is finding which packs might give you the best chance of trouble free Prius operation after rebuilding. I would definitely look at getting either a gen 2 or gen 3 pack if you can find one reasonably priced near you.

 

The other issue is the climate that the donor Prius drove. You want a battery from a Prius that was not subjected to a hot climate as this degrades all of the modules in the battery. A salvaged battery from northern climes is likely to only have 1-3 bad modules even if from a high mileage Prius.

JeffD

 

I would think you could take the batteries from both packs and make one good pack. After all, you have 76 modules now. Surely you must have 38 good ones????

 

X2

This is very important but I imagine in some cases shipping might be somewhat prohibitive if you live way down south.
At least in Canada we should have a good supply of used packs for a very long time considering how cold winters are here.

 

The junkyard pack was from montana, 150kmi. It was on the shelf for 150 odd days. According to them, to have a part this long is why they had it priced at $350. Ive now pulled 2 modules from it and reassembled the original pack. Ive upped my charge amperage to 3.5, for some reason im getting better numbers at the higher amps. So going through and cycling them all once, then discharging to 7.8volts to ready it for reinstall. The capacities just arent there to invest much more time on this pack, but the car will drive without pulling codes I hope now that the 2 low voltage modules have been replaced. Ill decide from there on buying some gen 2 modules. After all with the spare core I can build a good pack while still being able to drive the car on the other one.

 

I ran some test cycles on some of the good modules in the junkyard pack and the numbers were dismal, worse than what I was seeing on my pack. So I found a couple that came close and had good voltage to install in my pack. I think the rest of this pack is probably not worth the time. Hopefully gonna wire it up in parallel tomorrow and once equalized, install it and see what happens. Since im new to this whole thing, am I correct to understand that I can use gen 2 or gen 3 mods, and that they can come from a prius or a camry hybrid? Think I may start searching tomorrow, ebays pricing is out of line on these newer modules, 1600 for just 38 mods, the local hybrid shop will sell a balanced and mached complete pack for that. If I can get the modules for under 1000 and balance them myself I think it makes sense.

 

It's a good idea to use all modules of the same generation as the gen2 modules were improved in 2006 and the gen3 modules may even be improved again. The improvements were in the effective series resistance (lower in the newer modules) and the ability to handle a bit mopre current without overheating. Modules with a higher series resitance than the others will exhibit more voltage drop when asked to supply high current which may trigger alarms.

JeffD

 

Thanks for the input. Ill be researching some more tonight and tomorrow and hopefully find the right direction to head in.

 

So.....if I am rebuilding a 2005 pack should I use 2004-2005 modules only if I am just replacing one or two? The 2006-2009 module would have different properties and not work well with the older modules?

 

The newer modules will have a lower series resistance, but using very old modules is also iffy. We were discussing recent gen2s vs gen3s.

JeffD

 

Would there be a problem mixing gen2 and gen3 modules in 1 battery pack?

SM-N900P ?

 

When you rebuild an HV battery you want to maximize the period over which all of your modules (and the 6 cells within each) will have the same voltage independent of the battery State-Of-Charge (SOC) or the load current. To do this you first balance the cells within each module and measure both module capacity and series resistance. You want all of the modules to have similar capacities and each module pair should have similar resistance. So I would pair each Gen3 module with one of the higher resitance Gen2 modules so that the pairs match well.

JeffD