Prolong Battery reconditioning

Working on my grandson's 2005 Prius with 190K miles and original battery. It has been throwing some codes. First one was a misfire code, so we replaced the plugs. All good. Second code was for the hybrid battery system. I think it was P0A80. Check engine light stayed on and I decided to try the Prolong system reconditioning on this vehicle. Priuscamper and I did a pretty serious rebuild job on my 2005 prius earlier this year, so I have some background with this stuff, but not a lot.

I borrowed the prolong charger and the manual discharge double light bulb device and started by pulling the covers off the pack in the car. Connectors and nuts were not very corroded, so I am not planning to change them at this time. Basic voltage readings on all the cells looked pretty good. None of the cells jumped out as bad, but I did not load test, just a voltage reading on every module.

I put on the prolong harness and topped the whole pack. I went to 243v and then moved to the discharge stage. I thought I was being pretty careful, but that turned out not to be the case. Special tip: hook up the multimeter to the double bulb manual discharge before you put the bulbs in or attach the manual discharge unit to the prolong harness. I did bulbs and harness first and I created a short with the dangling leads and blew the fuse on the prolong harness. Then I broke the orange shutoff switch when I was working on that. Then I closed the garage and quit auto work for ten days, while I acquired more fuses and replacement switch.

Went back to the garage and replaced the fuse, buttoned everything up, gently installed the shutoff switch and powered the car up. Everything looking good. All lights gone and the car moves, so that was a relief. I was worried I had blown more than just the fuse on the harness. I started the first discharge carefully and in the right sequence. I had 217v when I started the discharge and I ran it down to 114v with the two bulbs in about 5 hours. I went back to charging and I am up to 222v after 14 hours. I would like to see it get back in the 235v range before I start the second discharge. I think I will only do two discharges, so the second discharge will be trying to get down and stop around 84v.

I have plenty of time and I want to go slow and not make any more mistakes if possible. I may turn off the charger in a few hours and then turn it back on in the morning. I think I should be patient and keep an eye on charging voltage and let it get higher than the current 222v, but I am open to suggestions and thoughts about the process so far.

Cheers

Mike

 

Yes, I missed an opportunity there, didn't I. I was too anxious to close it up and get to the reconditioning after my two mishaps 10 days before.

 

Walked back down to the garage and turned the charger back on. I have been cautious the last two nights and turned off the charger. Maybe worried about overcharging, but I think the prolong charger should take that worry off the table. I think this is the first time this battery has been touched by anyone.

I hope/plan to hit the 235 to 240v range tomorrow before I run the second/final discharge cycle.

Thanks to you all.

 

Initial module test on the pack in my 2005 vehicle clearly indicated one module with a dead cell and the two end modules were also slightly under the range of all the "healthy" modules. All three of these modules looked much worse under load testing and we switched them out and replaced with healthy modules. I get what you are saying about running the load test and I think it is certainly the best practice to get a battery back in tip top condition. I expect to end up doing that with this battery pack, but I am hoping to get six months out of this reconditioning so that I can do the real rebuild of the pack in a month with warm rainfall instead of the cold rain we get here in the PNW in the winter.

Ideally, I will be able to pick up an extra battery pack in the next few months, load test it, replace the bad cells and then just switch this battery pack out. I have friends with Gen 2 priuses, so we are all working toward this goal of having a rebuilt pack handy for quick install. We just need to get a pack or two ahead to make this work. So far, we have been on our heels a bit responding to packs with issues instead of getting on our toes with a couple of extra good packs.

I checked a couple at 6:30 am and I was at 229v. What do we want? Patience! When do we want it? Now! Hope I will get up to 238-240 later today and stabilize at some value in that range. Following raytheeagle's sage advice on this charge up.