rebuilt battery problems

Earlier this year a friend of mine had the hv battery code pop up and found out the battery could be rebuilt. They asked me if I was up for the challenge and after a little (not enough due diligence) I decided to give it a try.

It's a good thing they have a another vehicle since I didn't do enough research. The first attempt I swapped out the bad modules (2) only not knowing anything about the balancing. The car ran ok for about 5 miles and the lights lit up again.

After some more research and 2 more low voltage modules I ordered a x1 and x4 smart chargers. I had the settings correct except for the safety timer being set so the modules did not fully charge and discharge. Lights were on immediately.

Third attempt I put a couple extra modules in I had in on a couple off voltage modules. I did the balance (3-4 cycles until they were at equal top voltage) and wired them all together to even the voltages across the pack.

Drove fine for a few hours and a weak connection code popped up. Tore it down and cleaned up the corrosion much more thoroughly than the light sanding I did.

The car has been driven for approximately 3 months/3000 miles problem free and a sensor code came up. I erased it and drove it for a couple days and the battery code showed up again. I took it apart and found one of the sensor clips had come off on the bottom side of the modules. Reconnected it and drove it for a week. Over the weekend I drove it to a pool tourney 3 hours away (320 miles round trip). It made it up just fine but on the way back the battery code came up 2 hours away from home so I reset it (took my scanner with me) and finished the trip with my fingers crossed. Made it home fine. Started to drive it 20 minutes later and the code popped again.

I have found a lot of great info on this site that has helped a lot but I've hit a stump. I am either not typing the correct keywords in or there are problems I haven't noticed since this is the first Prius I've drove. So I'm asking for a little help since I can not figure our which direction to start exploring first.

I live in southern Indiana. The temp has been down in the mid 40's pretty consistently. The code comes up with in 5 minutes after start up if it does come on. Comes on approx 1 time every 4 days/12 start ups. 2 codes came at cold starts after sitting over night. 2 were after sitting after driving plenty long for everything to be warmed up. I pulled the battery and inspected. All but 3 modules are at 7.74 or 7.75v, 2 are at 7.82 and 1 was 7.65 which is in spec with them all falling with in +-.5. On three occasions I noticed the soc dropping to 2 bars and taking a while (2 to 4 minutes) to charge back up to lowest green or highest blue mark. The soc stays in that range for normal everyday driving. If I get on the gas aggressively it will drop to the lower blues but seems to charge smoothly. It doesn't charge and discharge rapidly. Towards the end of my road trip the battery seemed to over charge a couple times and kicked the motor on to assist burning the over charge off. The 12v was replaced right before I started on the HV battery. I pulled the cooling fan this time to clean out though it isn't too terribly dirty but needs cleaned. The car is averaging 39 mpg city and on the all hwy road trip (I intentionally drove 75mph on cruise to stress the battery since the code had not come up since I reconnected the sensor).

I'm sorry about the long post but I wanted to get as much info as I could. With the exception of the p0a80 code coming up randomly I can not find anything that stands out so I do not know where I need to start investigating now.

 

Which battery does the start up checks? What is confusing is that it does not come on every time and it is only when I take off the first time. If the code does not come on during the first acceleration it does not come on. I've tried several times to accelerate several times as fast as I can with out the ice assisting to maximize discharge and later in the drive smash the gas pedal to get both the battery and ice working together.

Is there a way to simulate a load test with the cover off such as hook up each module individually or in series with a harness I made for a couple hours and monitor voltage drop?

When I discharge and charge the modules what does the the lower number represent at the end of the discharge cycle. Could I do one discharge/charge cycle and get any readings from the results of that?