Gen II Prius Individual Battery Module Replacement

For that - workable solution I came up with is a 1.2Amp SMPS charger.

 

After rebalancing and charge equalizing all of my modules I have the a pack that looks like this.
The capacity is the final discharge capapcity of each module.
The 'delta volt' is the voltage drop after 1 minute with a 55w headlight.

Should i re-arrange the modules to even out the capacities? And do I need to discharge the modules before re-installing?

 

Evening out capacities is not the best strategy as the capacity of a pair of modules in series is determined by the module with the least capacity. A goo strategy is to load test each module (use a standard auto headlamp) as you did to determine the voltage drop when the load is applied (any module that exhibits a large "Delta-voltage" under load should be replaced). Then pair up modules so that all of the pairs exhibit the same total drop under load. That will minimize the chance that the battery ECU will see a significant voltage difference between module pairs and set an error code.

JeffD

 

X2

This is why I'd suggest running the voltage drop test with larger loads and for longer periods of time (most are running relatively short tests with relatively light load)........it sorts out the weak/strong so you can pair them and get a nice average drop which the hybrid ECU will be very happy with over the long term.

 

Thanks for the replies. Since most of my voltage drops were 0.15, with only a few at 0.16 or 0.17 I can't do any better by re-arranging them. What about discharging the modules before re-installing. I read somewhere that if the modules are too charged it will generate an error code. After equalizing the pack by connecting all of the neg and pos terminals, each module is now at 7.90 volts. Is this too high?

 

AS MTL-hihy noted, do the load test for a few minutes (same period for each module) and use a heavier load current (he used both the low and high beam filaments in parallel) to get a better reading on your modules. Note that this will also discharge the modules a bit to not generate an error. Remember to re-equalize the modules by putting them back in parallel after the load tests.

JeffD

 

X2

Good to note this as well, don't put full charged modules back in or you will get an error from the hybrid ECU. You want to aim for around 50-60% charge (between 40-80% is fine, nominal 7.2v = 50%) and balance voltages in parallel again before install. So 7.9v is a little on the high side, I would run some better load tests and drop them all back to around 7.2-7.6v, re-pair modules based on better load test results, then re-balance everything again and do your final install.

 

I finally got my count down timer/relay built to do the load test. It uses a sealed beam head light which I wired both high and low beam which has about a 6-7 amp load. I set the timer for 60 seconds. My battery has been sitting for about 2 months since I 3-cycled each module. Voltage ranged from 7.82 to 7.89 volts to start and after the load test the voltage drop was from .22 to .25. Is that a big enough difference to rearrange the pairs?

Thanks for any help

 

I just check the way that the pairs are installed and the load drop of the pair added together ranges from .44v to .50v. If I rearrange according to voltage load drop the range will be from .47v for 12 pairs and .48 for 2 pairs. I am going to rearrange them.

 

Much better results this time around and it sounds like you're on your way to getting a well built pack again.

 

How do I add pictures to my post?

 

For rebuilders out there that are done rebuilding their batteries. Are any of you guys selling your chargers? Or maybe I can rent them from you?

 

They will likely need them again, so loan or rent may be best.

 

I bought 2 for $110 each with no tax and free shipping. I can cycle 8 modules at a time.

 

So are you willing to sell or loan it to Lam?

 

Sooooooo.. you willing to sell or rent them? I can paypal you the full funds and when I'm ready to return them you can paypal me back funds and i'll mail them back?

PM'd you.

 

Hi I have a Gen 1 dead battery sitting for a long time . Can I follow the same procedure as the Gen 2 to fix it ?
Thanks.

 

Yes. Except you have 38 modules to deal with instead of 28.
If you plan to charge the whole pack at once you will need a higher voltage charger.
I have revived several prius that were sitting for months and years. It is a satisfying but sometimes frustrating adventure. Before even messing with the battery I would make sure the gas engine spins freely. The gas engine may be locked up from sitting so long.
Then you'll have other fun stuff like the fuel pressure, a/c compressor, throttle body, ignitor, spark plugs, and MAF to deal with.
Seriously though, if the gas engine is locked up that can be more serious than a bad pack.

 

Thanks Eric for your feedback. I guess I have a lot to do.
Is it a good idea to replace all my cells with Gen 2 2009 cells, or may I just replace the failing Gen 1 cells ?
Another question: Where can I find brand new cells ?(Either Gen 1 or Gen 2 ?)
Thanks.
Eddy2014.

 

You cannot buy aftermarket new cells...... yet.
So only way is to get new cells is to buy a whole pack from Toyota.

Do not mix Gen 1 and Gen 2 cells.
If you only need a small number of replacement modules let me know. I've got some good Gen 1 modules around here.

If you want to replace with all Gen 2 cells, you'll need 38 modules. Which means you'll need to scavenge from two Gen 2 packs. (Gen 2 packs only have 28 modules total)