I stumbled upon this community by chance, knowing nothing except batteries.
For years, I worked at a battery pack company. A friend of mine had a broken foil drive, but buying original battery packs in China was expensive and difficult. So, he asked me to help find a solution.
At first, we provided a fix, but the battery overheated. After adjusting the assembly method and improving the insulation, we made it work better.
Later, I listed our solution on our website—and slowly, orders started coming in. But with each new inquiry, I realized I knew nothing about the device model numbers—only the battery pack specifications.
I also noticed that many people here have deep expertise, but batteries are often the missing piece when building alternative parts.
So now, I’m here to help.
Feel free to ask me anything about batteries—I’ll do my best to assist!
I bought a gen 2 foil drive slim with d battery last year and had a great experience until I forgot to remove the battery from the unit for 2 weeks. I think it went dead because it wouldn’t charge back up. I also have an ebike with a panasonic battery which i was able to recharge when the same mistake was made. I guess the bms won’t allow it to be recharged. I read about waking up the bms and tried it with an 18 volt battery from my drill. finally the voltmeter showed it was taking a charge so I moved to my foil drive charger. Even though the charger continued to blink green it seemed to be working. Then the charger turned red which is the normal charging indicator. It never turned green so I stopped charging when the battery had about 46 volts. Yesterday I took the foil drive out for a spin and it worked fine for about 5 minutes then was very week. voltage reading was then about 33 volts. Can this near new battery really be ruined by 1 complete discharge? Can I send the battery somewhere to be repaired? Thanks for any advice you could give. Mac
I’m anything but a battery expert so hopefully a more knowledgeable person will chime in.
The battery cells have a spec voltage that they are designed to work in and going below (in your case) or above (overcharging) can cause permanent damage. Perhaps not to the point of complete failure but certainly shorter lifespan. Lots of info on the web and I have found this site to be a good source of info
From my limited knowledge you might have trashed the pack by charging it too quickly during the restore process.
Dear Mac,
Thanks for your trust, at you case I think there is some problems for the cells inside due to the over discharge problem has been made.
1, The foil battery designed for high power, so the PCM designed may not very sensitive to the small current consumed for self-discharge. So after 2 weeks will have problems for the battery.
2, I am not sure about the exactly battery pack you used, 10S or 12S maybe? It is probably have been over charged if it is 10S battery pack, need check after you send me more details.
3, Since the battery pack has been used for a while, li-ion cells have limited cycle life, so after many cycles, one over discharge, the cells inside may has some problems, this leads to the week performance.
While charging my foil drive travel battery , it stopped charging , when to green for a bit , then red and started charging again. Happened repeatedly.
On the removing the battery and on closer inspection, it seems like the battery is seems damaged on one side, very small damange. I have attached a picture of it.
I reached out to foil drive, and they will sending me a replacement battery.
What I was trying to understand is it this battery is damaged ( and could potentially cause a fire? ). The damage seems really small on the outer edge only,so doesnt seem like anything inside would be damaged.
Is it okay to try to charge this battery and use it again ? If it charges normally fully, any issues or risks with it ?
im trying to attach a video and some more images, but its not allowing me to since i am a new user. I could maybe email them to u ?
2nd that opinion
OP got free replacement and even a new battery would only be between 300 and 800 Euro? Thats cheap compared to a house fire Especially now that OP admitted publically that he knew about the fault…
Fair point. The only thing is it will be a while before the replacement battery reaches me. I dont want to have less time in the water. From your responses, it sounds like it can be quite risky.
There is no scope of getting this fixed/repaired right ?
Also, if not, how are you supposed to discard these batteries?
Especially now that OP admitted publically that he knew about the fault…