Charging NiMHand NiCad batteries

twowheelsgood

Senior Member
Depends on how "intelligent" it is.

NiCd and NiMH both need constant current charging and are best terminated with "delta-peak" detection i.e. you charge, the terminal voltage increases until it reaches capacity then it drops.

This means you can usually use the same charger. Lead acid and lithium ones are different.
 

domtyler

Über Member
twowheelsgood said:
Depends on how "intelligent" it is.

NiCd and NiMH both need constant current charging and are best terminated with "delta-peak" detection i.e. you charge, the terminal voltage increases until it reaches capacity then it drops.

This means you can usually use the same charger. Lead acid and lithium ones are different.
Is that a yes or a no?
 
Hmm... thanks for that.

Methinks I'll give it a go, but do it while I'm in the room to keep an eye on it and see that all is well. Be good if it works - I have a few NiCads left that fit bike lights, and with using them mornings already and evenings as well soon, I thought it a good time to investigate the situation.
 

marinyork

Resting in suspended Animation
Location
Logopolis
Beanzontoast, your NiCds work well in bike lights? Whenever I've tested NiMHs in bike lights e.g. my rear cateye TL-1000 they don't work very well at all even with 2700mAh. You get a basic brightness equivalent to the having a set of Alkaline batteries that are a few months old - all right but bad enough that I've never bothered. My front bike lights seem to be more satisfactory though but it's such a hard job getting the batteries out I never bothered.
 

twowheelsgood

Senior Member
Rechargable cells are not good in low-drain applications like rear LED flashers. The cell voltage is only 1.2V as opposed to primary cells (normal batteries) which are 1.5V. Often this means control circuits like the flashers don't work or at best the light is dimmer. I have a low power front lamp that won't work at all with NiMH.

In high drain appliances, like a headlights they are actually better. The reason is because rechargeable cells have a lower internal resistance. When delivering a high current, the normal cells voltage will drop below a rechargeable and will not be able to deliver as much current to the load (lamp).
 

marinyork

Resting in suspended Animation
Location
Logopolis
GrahamG said:
Interesting Mr twowheelsgood - may have to give over the LED light rechargeables to the new Wii controllers!
LOL. Best of luck there. Interesting explanation there, I did know about the 1.2V thing.

Wii controllers eat batteries. Whatever battery is in there they just drain. It's so bad I take them out. On rechargeables I've played on ones that have drained in nine hours (not continuous play, just left in there). I find it's best to have an army of low capacity NiMH batteries for the Wii.
 

domtyler

Über Member
beanzontoast said:
Hmm... thanks for that.

Methinks I'll give it a go, but do it while I'm in the room to keep an eye on it and see that all is well. Be good if it works - I have a few NiCads left that fit bike lights, and with using them mornings already and evenings as well soon, I thought it a good time to investigate the situation.
Yes, if it starts spurting acid into your face unplug it immediately.
 
I'm a recent convert to led lights, having used bog-standard bulb-driven jobs until now. I've got two identical sets of Cateye front and rear led lights for myself and Mrs B, so will see how they go with the NiCads first and the NiMHs second. Will be interesting to find out how they fare.

I would expect in these eco-aware times that designers of modern led lights would assume people would want to be able to use rechargeable batteries in them - don't you think?
 

marinyork

Resting in suspended Animation
Location
Logopolis
beanzontoast said:
I'm a recent convert to led lights, having used bog-standard bulb-driven jobs until now. I've got two identical sets of Cateye front and rear led lights for myself and Mrs B, so will see how they go with the NiCads first and the NiMHs second. Will be interesting to find out how they fare.

I would expect in these eco-aware times that designers of modern led lights would assume people would want to be able to use rechargeable batteries in them - don't you think?
To an extent. I wanted to be able to use rechargeables. However my first set of rubbish alkaline batteries lasted over a year in my rear light and I was giving them a right hammering, doing a lot of night-time winter cycling. I think a year's perfectly legit to be honest. If I was using a light that required more than 2x AA and they didn't last anywhere near as long then it'd be very different (probably the situation others are in).
 

andrew_s

Guru
Location
Gloucester
marinyork said:
To an extent. I wanted to be able to use rechargeables. However my first set of rubbish alkaline batteries lasted over a year in my rear light and I was giving them a right hammering, doing a lot of night-time winter cycling. I think a year's perfectly legit to be honest. If I was using a light that required more than 2x AA and they didn't last anywhere near as long then it'd be very different (probably the situation others are in).
If you are using alkalines, you should check your light for brightness at the end of your journey before turning it off, not at the start after turning it on.
Nearly dead batteries will recover to some extent when left turned off for a while, so the light may be fairly decent just after turning on, but then fade back down to dim over the next 10 minutes or so. By that time your back's turned and you don't get to see the dimness.

NiMH rechargeables are never going to last more than a week or two, as they run down even whilst not being used ("self-discharge"). NiCd do it too, but more slowly.
NiHM rechargeables have double the capacity of NiCd if used over a shortish time in a front light.
The cadmium in NiCd batteries is a nasty poison if it ends up in landfill rather than being properly disposed of, so anyone who considers themselves to be "green" should avoid buying them.
 
Top Bottom