Hi folks, 02 my Prius, checked cell voltages using halogen bulb for load/1 min. all cells read very close to 7.77v uner load after 1 minute. But then I went back and checked for leakage from cell terminals back to the battery rack, and found 3 cells with leakage from .01v t0 .40 v. Should I ignore the voltage leak and run these cells? Thanks, Robert
Perhaps you might explain how you did the leakage test? Since you have the pack out, take the time and do it right. Remove the modules; wash and dry, and; install and test. But I would generally prefer to have the module capacity checked for all of them and then restack with weakest and strongest together. Bob Wilson
Hi Bob, thanks for your reply, I have read some of your posts here and I value your advice based on posts you have written and the miles you have racked up on Prius. I am a long term gen 1 Saturn guy looking to be a gen 1 Prius guy. I bought this one with a suspected weak HV battery, put in a new 12v battery and humped it 100 miles home getting nearly 60 mpg. I will take your advice and remove and wash/dry cells-I am still looking for a way to test cell capacity in Ah. I took off the bus bars and did the volt test with a Halogen headlight high and low beam for load and was happy with the nearly equal readings under load and after recovery there. My big question is on cell voltage leakage on 3 adjacent cells. I cleaned around their terminals and retested, no change. I am using a multimeter on the 20v range, putting one probe on cell terminal with the other test lead on the metal battery rack, I did test all terminals on both sides of the battery pack...found 2 with minor indication at .01v and one at .4 v. all other terminals zero. Is that almost-half-volt leakage indicating a bad cell? I did try more sensitive volt ranges, of course got mathematically equivalent readings. I found a lot of posts on voltage and load testing, but nothing on voltage leakage to the battery rack. Should I run those 3 cells or change them out? Tanks, Robert Mencl
The fact that you can measure any voltage from a module to the battery case is indicative of an electrolyte leak from the module to the case. That leak provides a circuit from the module to the case. Hence for a complete job you should replace all three modules. The traction battery ECU will likely log a high voltage ground fault code when the ground fault gets bad enough, DTC P3009.
Thanks for all the help gang, got the battery back in, codes are gone, got 57 mpg today in 40 miles of mixed driving, can go miles before the ICE kicks in. (how well does Prius fuel computer compare to actual fuel burn?) Apparently my driving 2 weeks ago for 60 miles with the battery safety plug removed did no harm. (car was already running when I pulled the plug) Did not find any cracked cell cases, but did find traces of electrolyte, carefully checked cases for leakage with a voltmeter and cleaned at all indications of voltage leakage, not with water but with acetone, which works well and dries immediately for easy retest with multimeter. I now have no voltage leakage to the battery rack or to adjacent cells. Found a good way to fix broken voltage sensing connectors, will post pics under a new thread. Audio cassette in an 02 car, Jeez...
