Easy way to test for a bad cell

Thanks for sharing that. It looks like a very convenient way of getting some consistent numbers on each module.

Just for people coming along afterward and for the sake of consistent terminology, the OP means modules where he states cells.

A Gen 2 Prius has a battery comprised of 168 1.2 V (nominal) cells. There are 6 of these cells packaged in a module. There are 28 modules. Modules are paired into blocks for monitoring by the battery ECU. There are 14 blocks in the battery. Battery modules are counted from the right side of the car being number 1 to the left. Number 14 is nearest the electronics bay on the left side of the car.

 

Glad to see this community still going strong (as our beloved Prius)!

Chris, your test method was indeed creative. But are there devices more suitable for this kind of testing? The battery tester you used was originally designed to test the 12v starter battery, not for a 7.2v (nominal) module. Other than worrying about the reading would be inaccurate, I do not know how that "500A cold cranking amp" was tested, and I wouldn't attempt (until I watched your video) to use it, for fearing that it would draw too much amps from the battery module thus potentially damaging it.

In a broader sense, my question is on how to evaluate the module's health. I had a batch of spare modules. After reconditioning, they fall into these 3 groups:

1. Some can provide 5+ Ah power when discharging to 6V. I believe these modules are still in good condition.
2. Some can only provide 2.5 Ah power when discharging to 6V; but they can still approach 5Ah if discharging to 4.8V. Are they still good to be use?
3. Some of them have a voltage lower than 1V (gasp!), and they do not take charge at all. Are these modules dead dead dead?

A follow-up question would be, how do we deal with the modules in category 2 or 3? Any recycle facility can take them?

 

After seeing this video, and still with the P0A80 DTC despite changed what I tough was the #5 indicated on Dr. Prius app a couple of years ago (never paid attention that the app referred to a block and not a module). Periodically clearing the code, reconditioning with the prolong charger and discharger twice per year. I decided enough is enough, so not having a main sticky post showing the troubleshooting, I found your post and about the harbor freight tester. Already purchased another 2 reconditioned modules, and in the meantime found this tester on Amazon for just $20 so I hope it works similar to yours. http://www.amazon.com/dp/B09TNFLNGL?smid=A2BO83Z9IEMSCG&ref_=chk_typ_imgToDp&th=1

I hope this time I will succeed. My kids need their 2011 prius, so I've already replaced the engine due to the infamous head gasket-engine explosion, and I am working DTC by DTC until all of them are cleared. May be next week I will be taking the car to the dealer so that they can upgrade the cal version.