i had a problem with my prius 2006 hv battery failing block number 3 and i took the battery apart and measured all the cells and each cell measured 8.24 to 8.27except one measured 6.99 and it was cell number 5 8.27 8.26 8.25 8.24 6.99 8.23 8.24 8.24 8.23 8.25 8.26 8.25 8.25 8.25 8.24 8.25 8.26 8.26 8.24 8.26 8.24 8.25 8.25 8.27 8.25 8.27 8.26 8.28 so i went ahead and replaced it with a cell measuring 7.59V. i tried to nimh special charger before i did that but for some reason it did not work. i put the battery back together put it in the car drove the car with no problem for two weeks. checked it again and now block 9 failed. my question is it because the voltages for the cells were high around 8.24V thats why the cell is failing one after the other. or is because I did not balance them although you can see all the blocks have 16.7Volts. Posted via the PriusChat mobile app.
When you have an HV battery apart, you need to load test every module and replace those that do not maintain their voltage compared to the others. Just looking at the resting voltage is not a sufficient measure of module health. Jeffd
It's the load testing that ensures you have modules that match well when you put the battery back into service. Just use a simple tester like this: Prolong™ Battery Module Load Tester – Hybrid Automotive (make sure you test each for the exact same amount of time to ensure accuracy) I also suggest using the HA charger to help with balancing and battery life: Prolong™ Battery Reconditioning Package – Hybrid Automotive (not cheap but definitely worth the money IMHO)
