Possibly OT: Rechargable batteries question

Khannie

Can a ni-cd charger charge ni-mh batteries?

The charger puts out 120mA @ 1.2V, so it's not gonna burn down the house or anything.

Also, is there a better forum for this question?

PhilCurran

No that won't work It won't burn the house down but it'll ruin the batteries!

Khannie

Thanks for the reply.

Can you give me any more info on that?

What's the difference in how they charge?

Mutant_Fruit

It won't damage them (95% sure of this). However, overcharging the batteries will damage them. If your NI-CD charger has an overcharge protection feature, you should be safe using it. If it doesn't, you might as well bin it, and get a new charger which has that feature.

EDIT: Let me amend my post. It is possible to charge them up, without damagin them, BUT the charger will NOT know when the NI-MH are fully charged, so its likely that your charger will keep charging the NI-MH batteries once they are full. This will cause damage unless your charger is trickle charging (i.e. less than 80mA i think).

Lydesia

NIMH and NICD are too separte rechs so it wont work,.

Go into Maplin, i picked up a nimh/nicd charger with 6 recharable batteries for 22 euro.
bargin price i would say

Khannie

Mutant_Fruit wrote:

It is possible to charge them up, without damagin them, BUT the charger will NOT know when the NI-MH are fully charged, so its likely that your charger will keep charging the NI-MH batteries once they are full. This will cause damage unless your charger is trickle charging (i.e. less than 80mA i think).

OK, now we're getting somewhere

It's charging at 120mA. I worked out that it would take 30 hours for a full charge of my 2500mAh AA batteries at that rate (according to the battery itself and a little calculation), so, say I charge them for 20 hours, I should be ok?

Thanks for the replies. I'll look into getting a new charger, just not right now if I don't need to (by undercharging).

Mutant_Fruit

Yeah, you can work it like that alright, but you'd want to be sure that your batteries are wasted or nearly wasted before you leave them in for 20 hours. I.e. no half-draining the batteries, and then leaving them in for 20 hours.

Isn't the time needed for charging gotten by 2500/120? That would mean 20 hours charge for a complete drain to a complete fill...

Khannie

Mutant_Fruit wrote:

Isn't the time needed for charging gotten by 2500/120? That would mean 20 hours charge for a complete drain to a complete fill...

Yeah, but not all the energy that hat goes in to charging the batterty comes out as useful current. Around 33% (or 50% depending on which way you look at it) loss seems reasonable to me.

Thanks for the answer MF. Just what I was looking for.