Traction battery repair / recondition with HA charger

Have you ever disconnected the buss bar harness from the battery ECU? The fact that module #9 keeps failing indicates that there is problem with the connection between the harness and the ECU which is causing that module to consistently fail.

 

Block 9 has 2 modules, are you replacing both?

 

Since block 9 seems to be an issue, shuffle those modules around to maybe block 2. Then see if block 2 gives you problems. If block 2 gives you problems, then it's the 2 modules that have an issue. If the error continues to be block 9, then it's probably not the modules.

Replacing with used modules may not always give you good results, those replacements could be bad

 

Well if you can get 2 new modules, that would be the best. Replace both modules in block 9 with modules from block 2 (known working). Then put the new modules into block 2.

 

I don't mean brand new modules, I mean good used module

 

If the modules has a dead cell, it's not worth messing with it. Just change it.

Many ebay sellers sell really worthless modules with little capacity left. It works (maybe), but for a very very short time.

 

This is a very good example of why replacing modules is a crap shoot. For modules to work well together they need to have similar capacity but more importantly they need to have very close to the same internal resistance. A module that performed well in one pack may not perform well in another for the simple fact that it is better or worse than the group. Modules with lower resistance tend to run at higher SOC's than the group and higher IR modules will run at lower SOC than the group. Both of these conditions if to severe will cause overheating and failure in a short time.

IR mismatch within a block pair is especially dangerous because the computer cannot detect it until the low modules drops out. This is indicated by sudden SOC drops on the MFD and engine RPM's jumping up during acceleration. Here's an example, this graph is a 120 Amp load test on 2 modules that were paired together in one of my cars. The block voltage would have looked ok under load but the weaker module was actually getting hammered.



If your going to replace modules your very best chance of success is to replace them in pairs and that means blocks as monitored by the computer. When you order replacements you need to make sure that you are getting modules from the same pack/group as indicated by matching first 4 digits of the S/N. When you put in the replacements it's a good idea to shift the pack so that the new modules have a temperature sensor under them. That way if they do happen to be weaker and like to run a little hotter the computer can limit current and increase fan speed to protect them.

Matt

 

No problem, hope it helps. Just to be sure I don't create confusion on the S/N stuff. Checking and matching the numbers is just an easy way to make sure that your using modules from the same donor pack. Healthy modules from the same pack normally work well together because they have been through all of the same charge/discharge and thermal cycles over their lifetime. When you start mixing modules from different packs especially if your mixing within blocks things start getting tricky. This is why people start seeing failures faster after the 2nd 3rd or 4th module replacement compared to the first.

And as far as your block 9 failing again, I doubt it's a bus bar or wire harness issue. I suspect that the module that went in as a replacement was just a bad match and it got beat up by the rest of the group.

 

Hello Matt,

I have a question. I have ordered three replacement modules and the s/n number's for them are all different. To be clear, the s/n number, is this the numbers to the left of the scan code?

 

Yes the s/n is on top of the module next to a qr code. They won't match exactly but if they are from the same pack they should all start the same. Specifically the first 4 digits. Do they?

 

no, so the three are all from different donor packs.

 

Matt your explanation about replacing in pairs is great.
So often when I sell modules in pairs people think I am just trying to rip them off. "But I only need one module, why are you making me buy two?".
You've put in writing what I have verbally been explaining to people over and over.

 

So I checked all of my modules and they were are between 8.04 volts to 8.08 volts, except for one, which was part of block 7. the one module was 6.7 volts.

So I used one of the three I received and I placed it on the middle heat sensor.

Turned the car on and drove it and no issues.

the one I place it with is 7.30 volts.

I plan on purchasing the discharger and following the discharging/charging procedure from prolong charger manufacturer.

hopefully this will last at least a year.