Looking for guidance - battery reconditioning

welcome!

get tech stream, and read read the battery building threads. it is a lot more complicated than you are thinking.

all the best!

 

Open the battery and take a look at the voltage sensing wire ring terminals and the crimp connectors. Also check out the orange plug that goes to the battery. Checking them for any corrosion or breaks.

 

The absolute voltage of each cell is more important than the balance.
Nowhere in your post did you tell us what the cell voltage IS.
Maybe they ALL are low.

 

Corfish,

x2 on eric's post

There are a few members here who have significant experience disassembling and reassembling the batteries. You have a great pool of knowledge to draw from. Don't worry so much about a 0.1 volt difference between modules. As a test (and documented in this forum) I installed a module that was somewhere around 0.3 or 0.4 volts different into a pack that had a single failed module. It worked fine. Don't get caught up in sweating minor voltage differences. A module with a bad cell will drop down to about 6.4 volts. That's where problems really start.

Let's start from the very beginning, since I-net troubleshooting can sometimes go off track.....
What were the original codes?
What did you use for your replacement criteria to determine which module to pull out?
Did you disconnect 12v battery while working on the HV battery? (this will reset all codes)
What codes came back and when?
Did you have any problems getting the car to start after the repair?
Were you able to drive the car after the initial battery repair?

I also agree that the current range of module/block voltages would be good info.

 

Cor,

Take a look through this thread:

Dorman HV Battery with a new lease on life..... | PriusChat

This is a Dorman rebuilt battery that failed in a fellow forum members car. In the first few posts, there is a spreadsheet where I recorded each modules voltage and then did a discharge of each one to document how much energy was in each. You'll notice there can be modules with full voltage, but very little capacity. You could be running into something similar. A module like that would easily throw a code.

 

Real question is how much time you have on your hands.
There are 28 modules.
If you do one a day, that will take you about a month.

For example charging at 1amp, a 6.5amp hour cell takes about 6.5 hours from empty to full.

Yes you are doing it much differently than the car. You are going far beyond the car's parameters. The car never takes it to 100%. The car never take it near 0%. Bit you can.

You can do the battery drain test in whatever manner you please. There isn't a single "right way"that folks follow. Whatever you use, apply it consistently. The car wants modules that are similar to each other. You can build pretty crappy pack and as long as it is consistent, the car will tolerate it.

 

Corfish,

Yes, each column was the amount of mAh discharged from that module. I have enough chargers that I can do all 28 modules simultaneously, so it saves a lot of time.

Yes, the battery is only as good as it's weakest module.

The great thing about the Prius is that the brain cares more about balance than overall capacity when it comes to normal operation. Overall capacity makes a big difference in how long the engine will stay off when at a redlight, running the AC, etc, which also results in better MPG.

You can think of it like this. If I could find a place that sold custom batteries, let's say I buy 28 brand new modules rated for 2000mAh capacity. I also buy 28 modules rated for 10,0000 mAh capacity. I build 2 HV batteries and install each into a different car. In the big picture, the cars are both going to work. Each of the 28 modules in each battery will react almost exactly the same as the other 27 when put under load, resulting in no big differences in voltage between the 28 modules.. The 10,000 mAh battery is going to be able to supply power for a MUCH longer time before the engine needs to run to replenish it. It can accelerate harder and longer, it can run the AC longer, it can run on electric for longer periods, all resulting in better MPG. The 2000mAh battery, under light conditions, would be almost indistinguishable from the 10,000mAh battery.

Now, if I accidentally installed one of those 2000mAh modules in the other battery, it would probably code out the first time I tried to pull out into traffic under heavy throttle, since the voltage on that module would drop much lower than the other 27.

If I accidentally installed one of the 10,000mAh modules in the other battery, it would also probably code out because that single module would hold a much higher voltage under heavy load, potentially tripping the delta V limit. All the ecu looks at is the highest and lowest block voltage to determine if a problem exists.

 

Yes. A new module is rated for 6500mAh. A 1 amp discharge would be 1000mAh, so it would actually take 6.5 hours to fully discharge a new, fully charged module.

Your B6, if I remember correctly, is rated for a 5 watt power dissipation, so although set to 1 amp, it's probably discharging at about 0.7 amps, and will slowly increase (but never exceed 1 amp) as the module voltage drops. (watts=voltage x current)

Are you performing these charges/discharges while the module is clamped in the pack? If you don't have it clamped, you're going to experience some fatal swelling of the module. I always leave mine clamped for minimum 1 day with cooling air flowing after cycling, just to make 100% certain no swelling will occur when clamps are released. It's a bit overkill, but it works for me.

 

That will depend on your settings. If you program a 2 amp charge with a 8000mAh limit, it will charge for about 4 hours and 20 minutes. It will charge for several minutes, then stop to check for voltage droop, then start charging again. It will do this continually, until it either detects delta peak voltage, hits the programmed max mAh, or programmed time limit. The delta V is what a charger uses to determine a battery is at it's full charge condition.

 

What is it displaying for amperage on the discharge?
A NiMH battery has a plateau at ~7.2 volts so hanging out at 7ish for a bit isn't unusual. Discharging only 1500mAh over 5 hours if set to 1 amp (actual ~0.7) is odd.