Current State of the Art in Battery Balancers?

This is an individual module test on a core 2nd gen battery purchased on Marketplace that's been refurbished before and failed and has been sitting 6 to 12 months. Some good modules from this battery will be used to fix the two 2nd and 3rd gen batteries that are being refurbished.

This is the Harbor Freight Viking Battery System Analyzer. It's a 12 volt tester so the readings with a 7.5 volt module are not too accurate, the CCA for sure. So while the readings may be inaccurate they are consistent, so it makes a good comparison test so the bad modules can be identified. Its noted on some of the YouTube battery refurb vids that you can't just grid charge a battery that's got the red triangle P0A80, you have to locate and replace bad modules before you grid charge or the battery will fail.

It looks like the modules are either in the 7.5V range or the 6.3V range with not too much in between. And the CCA numbers are all lower, and the resistance readings higher, with the 6.3V readings. Also it looks like an abnormally high internal resistance reading of 8.87 m/ohms is an indication of a hard fail with the 6.07V, 338 CCA readings being one of the lowest in the pack. There's also one module the tester refused to test, a volt meter reading was taken on that one at 5.68V. Also note than none of the low voltage modules are together in any of the 14 battery blocks. So all the bad blocks are only 1/2 bad. Also note the worst modules are in the center of the battery where it runs hotter. It's recommended that you swap the center modules to the outside before you grid charge.

All 3 of the Prius battery apps were used on the CT200H but I haven't yet been able to really pin down which modules are bad or good the way this Viking tester is doing. But I'm still learning the apps. Also note the apps only test battery blocks not individual modules because that's the way the ECU's look at the battery. So you are going to have to additionally find the good and bad modules within a bad block.

Right now it really looks like this is an economically viable endeavor, if you have the time to spare. About $1200 total investment so far which includes charger / discharger, core battery, testers, OBD2 module, app upgrades, new buss bar hardware. I spent $1500 5 years ago for the new D cell conversion and that's about the price of a refurbished battery. And the $1200 will get 2 batteries up and running, and the charger will be used again to maintain the batteries and extend life.

 

I'm a HW/SW/FW engineer myself. I understand circuits, but never have designed them professionally, working far more on the SW/FW side. That said, I've been collecting tidbits to do a variation of what you're describing... Just hasn't come to the top of my stack to Get It Done quite yet. Can't wait... looks like a fun project!

* Primary difference: what I'm aiming for is accurate, repeatable characterization of battery modules (each w/ 6 cells, so nominally a bit under 10VDC total). Doing that is NOT easy right now. Once I have that data, including reasonably accurate internal resistance, I firmly believe the important elements of a battery pack rebuild can be done with solid confidence:
* Eliminating bad modules
* Creating module pairs that pass muster in the Prius
* Sorting the pairs so the most at-risk pairs on on the outer edges (coolest temp)

A few items look pretty useful to me:

* TestController: a free app able to drive a WIDE variety of power supplies, loads, meters and more.
Program that can log from many multimeters. - Page 1
Test Controller introduction
* Programmable power supply, such as RIden RD6006
* Progrmmable load, such as DL24MP (150W per module, can have up to 9 modules!!) with 4 wire sensing
* A programmable meter able to do the measurements needed for reasonably accurate internal resistance measurements, ie low resistance at significant voltage or current. I happen to own a Fluke 8808A which while a bit slow seems reasonable for the task...

Put those together and it's not too hard to cobble together a rather nice module tester!

Now I can't wait to get back to this