18650 batteries from a laptop

sheepsteeth

how do i check if the batteries i have just taken out of my old laptop battery will be useable?

is there a minimum voltage i should be looking for and how do i know if they are safe to charge and whatnot

cooldad

3.7v I think. If they blow your fingers off they're not safe.

Try them with the charger on a metal tray or something, check they don't get hot, and don't leave them on overnight.

prawny

Between 4.2 and 3.7 Although I'm sure I've seen people running them down to 3.4 and being ok*

I'd better get re-reading all the stuff I got last winter, it's getting dark in the woods at 9pm now, soon it'll still be dark at 6 in the mornin too

*Edit! Don't quote me on that!!!!

prawny

Just found this, blame them if you lose your hands

http://www.ehow.com/how_7826542_test-li ... ttery.html

Giraffoto

prawny wrote:

Just found this, blame them if you lose your hands

http://www.ehow.com/how_7826542_test-li ... ttery.html

That article seems to be aimed at people who've bought a multimeter and can't be bothered to read the instructions. The problem with 18650s is that there are two types: some have a set of electronics built into them to prevent overcharging, and some don't. The individual cells in a laptop may not have the protection circuit because it's built into the casing, but this may be quite hard to check.

Second worst-case scenario: you try to charge an unprotected cell. After it reaches capacity it starts to get hot, and eventually bursts. This will spread bits of battery all over the room at quite high speed.

Worst-case scenario: you load your two-cell torch with one unprotected 18650 and a higher capacity protected 18650, both fully charged. When you switch it on the higher capacity cell dumps some of its charge into the lower capacity one, causing it to get hot and burst. Your torch is now a low powered pipe bomb, and will spread bits of battery all over you at quite high speed.

cooldad

But this is Sheeps - he loves bombs and stuff

YeehaaMcgee

It may be of interest to you that Lithium batteries have about as much chemical energy in them as a stick of dynamite.
They don't often go KABOOOM!, but when they do, you really don't want to be near it.
Seriously.

cat_with_no_tail

I now have a mental image of sheeps charging his batteries and riding his bike dressed head-to-toe in "hurt locker"-esque attire, just in case.

cooldad

As long as they make that in fat bastard size.

sheepsteeth

Cat With No Tail wrote:

I now have a mental image of sheeps charging his batteries and riding his bike dressed head-to-toe in "hurt locker"-esque attire, just in case.

Ive been in one of them.

cooldad wrote:

As long as they make that in fat bastard size.

they do!

YeehaaMcgee

I bet you use it as a gimp suit you dirty little minx.

sheepsteeth

i got mine fitted with the dildo so it doent move around too much if i have to walk a long distance in it.

(i dont actually ever need to wear a suit like this i might add, i just work with people who do)

YeehaaMcgee

I work with a lot of people that I wish I could force to walk towards a live explosive.

cooldad

YeehaaMcgee wrote:

I work with a lot of people that I wish I could force to walk towards a live explosive.

I'll see that and raise you about 99% of the entire population of the world. And all the horses.

cat_with_no_tail

cooldad wrote:

YeehaaMcgee wrote:

I work with a lot of people that I wish I could force to walk towards a live explosive.

I'll see that and raise you about 99% of the entire population of the world. And all the horses.

But...but....but....

YeehaaMcgee

FAIL!
You didn't even tinyurl it.

cooldad

Perhaps there was a clue....

cat_with_no_tail

YeehaaMcgee wrote:

FAIL!
You didn't even tinyurl it.

Pfff, it's late and I'm lazy.