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18650 - Rail went red hot??

724 Views 3 Replies 2 Participants Last post by  jbman

Complete newbie here, i am planning to make my EV conversion in a few years but figured the best way to get started would be to do some small battery projects, then a powerwall, then move onto a EV conversion (im considering converting an Aygo).

Anyway i had some old 18650's lying around and a bought a case for them for a cheap mobile battery, something like this:

The old batteries worked fine, not a lot of juice left in them so i bought a set of new ones pulled out of unsold laptop batteries.

The issue is when i installed the very first battery the metal rails running up to the charge controller glowed red hot and there was a small spark when i pulled out the battery. Im afraid to put any more in to test the others now.

What could this be? Its like the battery just dumped all its amps all at once, does this kind of thing happen often? If so how should i test with a multimeter for example the rest of the batteries to see which are good.

Thanks a million!

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Sounds like a short to me.

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A short, where? I installed it in the battery pack, correct polarity. Where could the short be present?
In the box somewhere, if it’s not connected to anything else. The terminals on the battery had to have been connected to get the juice to make that rail glow. That’s a short of some sort. I’d double check all of the connections and wiring diagram if you have one. That, or whatever you connected it to is just drawing that many amps. Or the wire is too small.

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