Dissected a FoilDrive Gen 2 Max Battery

EFOIL.builders Electronics (ESC, remote, batteries)
1

I have been off the forum for a little while and not sure if this has been covered yet but… If anyone is interested in seeing whats inside a Gen 2 Max battery…

This is… well was… a 11s3p 40v v2 Max power battery.
A friend brought it by after having issues charging to see it was salvageable. Turns out the very end series cell group was dead (like 0v dead). These are totally potted in epoxy so not serviceable obviously. I used a flap wheel on a grinder to carefully expose cell ends so I could get voltages across all the series groups. While this won’t be running his gen 2 anymore sadly, I should be able to salvage the remaining cells to make a 36v pack for my homemade foildrive, ebike or something…

Yes I understand this is a grenade. Don’t worry, it’s being treated as such and will be stored outside in an ammo box. I’ve built several diy lithium ion packs in the past.

Hopefully someone finds this useful for building their own pack or possibly saving their FD battery. I do think it would be possible to bump a series group back to life if it fell slightly below BMS cutoff voltage. Just need to have a steady hand with a grinder to expose the bus bar and then recoat with epoxy after defibrillation.

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7 Likes
2

Is there any information on how many cycles the battery has worked?

3

That wont be available as FD use a simple BMS.

4

However, the owner can estimate how many times he used the device. At least approximately. For example, I ride two seasons, 40-50 times per season. The number of charging cycles is from 80 to 100.
I would also be interested to hear versions of the reason for the battery failure and whether it is typical for FD batteries.

5

No telliing but he did buy the system used and used it very frequently. So i imagine it had lots of cycles. FD warrantied the battery for him so I assume it wasnt so old that it was no longer covered.

6

at this price they could afford a bluetooth bms so you can check the state of your cell.

7

What kind of Bluetooth BMS can we talk about if they still use a cheap household XT 90 connector.