The Hundred Dollar Ebike Battery

antboy

Well-Known Member
Not even close! Bags are a fail! Military surplus ammo can with watertight lid gasket removed and grommet holes added for wire access. A reliable battery safe. I keep a smoke detector and a pair of welders gloves close by. https://batteryhookup.com/products/...3284258&pr_seq=uniform&variant=35691145101474
Yeah, I wouldn't trust the most common "fireproof" bags sold on Amazon and Aliexpress. The Crazy Russian Hacker tested a couple back in 2018 (still being sold to this day), and they're garbage....


Harbor Freight has a pretty good deal on 50 call ammo cans as well...


I have two issues: First is that 2 of my batteries are about 15.5" long, and every time I come across an ammo can, it's 12" or under in length, so I was thinking of using metal tool boxes (1 for each).

The second issue is heat. Metal is a great conductor of heat, so if you DO have a battery go into meltdown mode, the heat from the metal can cause it's own issues. I was considering buying a fire blanket as a liner, but then came across this video where an RC guy builds his own fireproof case using a tool box as well...


Essentially, he uses (probably Type X) drywall as an insulation layer. This is going to be my next project, once I get the drywall.
 

antboy

Well-Known Member
Mine is a 20MM can I believe. It's quite large and can hold 2ea 20Ah triangle packs.
Thanks! "20MM" was the secret search term I needed to find ones that could fit Silverfish style batteries.

I MIGHT still go with the tool box, but let's face it, ammo cans are cooler. :)
 

harryS

Well-Known Member
GerogeS posted about those surplus hoverboard packs in 2017. I was skeptical, but after reading some good test results, I bought a few and configured two 60 dollar 36V8AH batteries that I still use in 2020. There were some safety concerns. because they set up the charger connection wrong, but it wasn't hard to fix that. I store them in ammo cans or in cinderblocks.

Last year I bought some surplus segway/ninebot scooter batteries from the same seller in the first post. These were very well made. Machine welded batteries with sturdy battery forms. Dual temp sensors. The BMS only worked with ninebot chargers, so I replaced that. Made two 75 dollar softsided 36V10AH packs that I considered very safe. but they still get stored in a fire resistant area like the above packs.
 

harryS

Well-Known Member
What did you do to change the connections?
Thanks!

The hoverboards charged the packs thru the output connector, bypassing the overvoltage protection. If/when your charger failed, and went above 42V, you had the overcharged hoverboard fire.

I attached 5.5mm round connectors to the unused charger inputs. My original move was to replace the BMS, but after doing one, I realized I only had to add the connector,