What would happen if I...

P220C

Newly Enlightened
Joined
Aug 11, 2008
Messages
81
accidentally do this?

Battery.jpg


I'm not planning on it mind you, but I am working on a bike light, and am considering using Turbo Ferrets four cell 18650 holder wired in series as the power source. Just wondering what would happen if I accidentally inserted one of the cells incorrectly.

I'm going to be careful when recharging the cells and replacing them, but I am just weighing the risks and benefits of various options (ie a pre-fab pack with smart charger vs. 18650s in holder)

Edit: I am leaning towards the holder because it gives me future options: changing voltage, cell upgrades, replacing a bad cell, temporary bench power supply et al. As it is, I think i only need +/- 11.1 V, but if I'm wrong, it's no big deal to rewire the holder, and slip the extra cell in. Can't really do that with a pre-fab pack.
 
Last edited:

Mr Happy

Flashlight Enthusiast
Joined
Nov 21, 2007
Messages
5,390
Location
Southern California
Your circuit will potentially attempt to charge the reversed cell. If that cell started out fully charged, and if the protection circuit didn't cut out, and if the load drew current, then the reversed cell could be charged to a voltage higher than 4.2 V. Depending on the extent of overcharging that might damage it a little or a lot. In the worst possible case the cell might energetically disassemble itself.
 
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