Hi there I am experiencing the following problem. I removed the battery pack on a gen 3 Prius that is giving an error that the full battery pack needs to be replaced. I am trying to cycle each battery 3 times. However they discharge down to 6 v and give off only about 900 Mah on average. I can only get in an average of 2300 Mah when charging before it accepts no more. Has anyone any advice on how to restore these cells. They all read well above 7.2v so there are no dead cells. Thanks.
Hybrid Automotive has a presence here on PriusChat and has some well respected equipment for discharging & recharging Prius batteries to prolong their life. I do not know if they do Gen 1 but they do Gen 2 & 3. See Traction Battery Preventative Maintenance - Hybrid Automotive Chargers | PriusChat
Are all 28 modules exhibiting this very low capacity or just a few? In general, modules with less than 3000 mAh capacity do not have much life left in them. Some people have had success recovering some capacity by charging the modules at a very low current - about 300 mA. This charging rate minimizes the expansion of the module as it heats up. Takes a really long time to reach 6000 mAh obviously this way so a pack charger like the Hybrid Automotive makes this charging rate practical. Otherwise, your best option is installing a brand new pack if your Prius doesn't have over 250K miles on it.
Thanks for the feedback. Unfortunately I have tried the slow charging with lower Amps but this also yields only marginal improvements. Am now considering rehydrating with caustic soda solution that I read on another site. Has anyone here had any success with rehydrating?
I have had the same problem with several of these batteries/modules. They give off what I call a false state of charge/good. Unlike the gen 2 modules that are usually pretty obvious to find the bad ones, these all appear good on the surface. But if you put them in a car or put a load on them, it's a whole different story. One way that I've been able to get a good read on these batteries is to use the Hybrid Automotive Charger to charge up the battery pack. Once it stops charging use their simple discharger with two 200 watt bulbs to take the pack down to 196 volts. Immediately go through and check the surface voltage on each module, and sometimes you can identify the bad ones that way. If you are doing them individually, I've had the same problem there, too. I have had the best luck though with my Turnigy Accucell 6. I set the charge current to 6, the auto-charge current to 5 and the discharge to 1.0A. Don't give up and keep trying different settings with your charger until you start making progress.
