Repair of Upper HV Battery Pack

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Dec 26, 2022
My 2013 FFE got the "stop safely now" message, and I confirmed coolant in the Upper HV Battery by pulling the two rubber drain plugs. My understanding based on reading this forum is that the Upper Battery is shot and needs to be repaired (or replaced). I have zero experience dealing with these batteries, but I am exploring options for what to do now that I am in this situation.

The only repair thread I have read (from sky_guy) involved removing, drying out, and putting back together everything; while removing and bypassing the coolant plates. What I haven't seen is what actually "breaks" when the coolant floods the pack?

Do individual modules or any electronics (sensors, etc.) need to be replaced? Or is nothing actually broken, and drying everything out and repairing the leak all that needs to be done?

If I were to find a used Upper Battery, would the replacement be "plug-and-play", or would I be dealing with several error codes and/or reprogramming?

Does the lower pack eventually experience the same fate? Is there anything proactive I can do to prevent the lower pack from failing?

Any experience or insight into the questions above, or how to best handle the situation is appreciated.
Looks like you are asking all the right questions. I recently repaired a contactor in my battery pack, so I've been all over the forums, YouTube, and Facebook looking for information, so I think I have some feedback for you.

On YouTube somewhere, I saw someone who had taken apart a battery pack that was corroded. As we know from sky_guy, there is a point where the battery only has to be dried out. I also saw someone on facebook indicated that they used flex seal to repair the leaky battery. So to your question, it might be dryable and fixable, but you will just have to initiate it and see. I think using the drain plugs to remove the coolant is the best first step.

As for the lower battery, I think I did hear of one case where that battery leaked too. However, it is very much less common.

Good luck. Sorry you are having to deal with the battery issue. Totally not fun.
What, if anything, needs to be replaced is ambiguous.

If you're lucky, it just needs to be dried and bypassed

If you're REALLY lucky, it can be repaired without a bypass.

If you're unlucky, you basically have to get another used battery to rebuild.
Thanks for the replies.

If I open up the battery, will it be obvious what is wrong? Or will it require complete disassembly and testing of components?

I am trying to gauge whether or not it is worth the trouble of a DIY repair vs sending it to someone with the know-how.
The likelihood is that when you open it up, there won't be anything that looks damaged aside from being wet.

It won't be until after emptying and drying it that you can determine if there are further problems that aren't immediately visible.

But at that point you can pull codes, knowing that whatever still had faults is not just throwing a code because of the coolant.

While there may not be anyone nearby to help hands on, in this age of telepresence if should be easy enough to manage a video call to assist in the process.

I haven't cracked mine open, so I can't personally guide you through the process, but I've kept tabs on what others have done and SO MUCH troubleshooting is not specific to a certain device or technology.

Here's the Discord we have going

This link will expire after a certain number of people join through it - that way I don't have to worry about it attracting endless spam joins by leaving it up.