Can I use a NiCD Battery charger on a NiMH battery?

Looking for a bit of advice please.

I have had to replace a dead battery in a Bosch GSB 12VE-2 professional battery drill. The original was a 12V 2,4Ah NiCd battery.

The closest replacement that I could find was a 12V 3Ah NiMH Vanon battery.

I have the original charger for the NiCd battery. (Bosch AL1450 DV 7.2V - 14.4V,  5A.)

Is there any reason that I should not use it to charge the new NiMH battery?

John

Edited By Breva on 23/06/2021 23:56:45

Hi John,

The subject was discussed here and here.

Thor

Breva

Best to check with Bosch. As its a professional tool the charger will have a full charge sensing with an associated widget in the battery pack itself. Usually a thermistor for older style NiCad packs. Dunno what an NiMH uses.

The charger for my old NiCad battery Makita drills handles both types and, as I understand things uses the sensor widget to set the correct charging strategy as well as detecting full charge. It also does several voltages. Clever little chappie.

The inexpensive consumer market chargers for standard cell sizes seem to use a sort of general purpose charging strategy which works OK(ish) but never, in my experience seems to properly re-charge either sort. The cells don't seem to last that long either. Maybe 50 to 100 recharges at best before landfill.

The Siemens Gigaset wireless wander phones I have are also supposed to be able to handle both types. Using standard AAA cells rather than old fashioned packs is nice but I'm convinced that the charger doesn't handle NiMH as well as it did the original NiCads. Don't seem to get the extra run time per charge I'd expect given the NiMH are larger capacity than the NiCad originals. Second set of NiMH have just gone in, first set did not last as long as the original NiCads.

Bottom line is that you need a power tool battery to charge properly and not be abused by the charger so its silly to take chances by using the wrong thing.

You may have to bite the bullet and transition to a modern lithium system. I ponied up and switched from NiCad Makita drills to the 18 V lithium versions about 3 years back. Wished I'd done it earlier. Now changing out mains powered devices for 18 v Makita as funds permit. 4 batteries and 2 charges let me share just fine. Bare tool offers are common from Makita which helps keep things within piggy bank capacity.

Clive

NiCd batteries are still widely available. Batteriesplus have tagged 2400 ma NiCds for just over £2 each for 10 (gives you 12 volts.) The snag with NiMh batteries is that they have less current output than NiCds so they are not ideal for things like battery drills. You will get less torque with NiMh batteries.

As far as charging NiMh batteries with a NiCd charger, it will work, but take a much longer charging time.

Andrew.

Edited By Andrew Tinsley on 24/06/2021 13:10:55

I re celled an AEG 14.4v pack with success using NiMh cells. The original cells were 1.5Ah NiCd the new ones were 3.3Ah. There was an option on a higher Ah of 3 so the charger would be able to handle the 3.3Ah used ! It worked well. The only thing I would say is that the new cells cost about £30 and I could have got a new battery pack for £37(but only 2Ah), this I only found out later, but I had the fun of doing the job. With everybody going for Lithium batteries the cost of NiMh may come down ? Good Luck Noel.

Will there be a big bang and magic smoke? No.

Will the battery recharge? Probably.

Is it a good idea? No. In the good old days batteries and chargers were both dimwitted so battery management was either done manually by professionals, or no-one bothered. Managed batteries have much longer lives and better performance than unmanaged batteries because the latter degrade. Big difference between:

• 20th century Lead Acid submarine batteries where engineers constantly controlled charge and discharge rates, monitored cell chemistry and checked the condition of the plates, and,
• Motorist charging a Lead Acid car-battery with a cheap charger. Car batteries are easily spoiled and there's a rich sub-culture of battery bodges to extend their lives a bit. Revived batteries are unreliable compared with batteries in good condition, OK to revive batteries yourself, but if you buy one you've been ripped off.

Modern batteries are likely to come with a built-in management system. The management system can be in the battery, in the charger, or both. What happens if the battery and charger are mismatched is anyone's guess. Expensive batteries and their chargers are often intelligent enough to refuse to charge unless they specifically recognise each other. Slightly less sophisticated systems rely on the battery telling the charger to maximise battery life by varying volts and current throughout the recharge cycle; the charge is optimised. Others simply limit charge time, rely on constant current, or have an overheating sensor. The customer doesn't know: he buys an appliance with a particular battery and a particular charger and is meant to replace them with compatible parts, not to mix and match.

Is it a bad idea? Maybe not. If the battery charges the result is unlikely to be outright failure. More likely, the battery won't quite be fully charged, and/or the number of recharge cycles it takes before clapping out will be much reduced: a battery that should last 1000 cycles, might only do 500 or less from the wrong charger. That may not matter!

However, if reliability is important, I'd try to find the right battery for the drill. Anything wrong with these?

Dave

I've done this accidentally through muddling up radio control car battery packs and settings on a programmable charger and only realising later, so while it may not be optimum I'd say it should work. I would have a try but keep an eye on it to make sure nothing gets overly warm.

Andrew - looks like £21 for 10, not £2. I thought that was too good to be true.

Hi, to all who answered.

Thank you all for your advice. I certainly learned a lot more about the subject.

The batteries that I have bought cost €37 for the two, so even less than re-celling the old ones. If they don't last I suppose it won't be the end of the world.

From your answers ,there would not seem to be any danger to the drill or the charger or " a big bang and magic smoke", all of which I wondered about. My use of the drill at this stage will mostly be light work, so taking stock of your advice, I'll just carry on using it with the new batteries for whatever long they last.

Thank you all,

John

I have had a few for the 2 Makita drills i have. The only difference is that it takes twice as long to charge, with the original charger.

Steve.

I've had problems with sophisticated chargers undercharging due to getting NiMH and Nicad mixed up.

Nicad have a voltage drop, where with NImH the voltage rise slows down (as I recall) so NIMH chargers can undercharge nicads and nicad chargers can overcharge NiMH (as I recall) I may have this slightly wrong

Trickle chargers at 1/10 C for 14 hours (i.e. 200mA for 2Ah etc.) will be fine for either chemistry.

Neil

Hi John

Personally I wouldn’t take the chance. NiMH batteries need more sophisticated chargers to avoid overheating and possible fire.

Charging batteries, especially NiMH, is one of the biggest safety related issues that power tool (etc) manufacturers worry about, so I treat them with a bit of respect.

Cheers Will

I think you are thinking of Lion batteries.

NiMH are the safest of the common rechargeables, without the toxicity of lead acid or Nicad and they don't burn l;ike Lion.

Neil

Many thanks for all the replies. I have a good handle on the subject now and since I have already bought the batteries I will follow the advice and proceed carefully.

I gave the drill its first workout yesterday and all went well with torque aplenty! Happy days!

Yes Neil, you’re right.
Sorry for the false concern, I don’t have direct experience with NiMH 🤪

Cheers Will

Didn't realise Lithium Iron was a problem too, thought it was Lithium Polymer (Lipo).

Regards Ian.

Lion = Lithium-ion (not iron although some formulations use iron in them) is a catch-all for all lithium batteries including Lipo.

en.wikipedia.org/wiki/Lithium-ion_battery#Fire_hazard

(Edit) I guess you thought I meant lithium-iron-phsphate (Life) cells - these are indeed much less likely to catch fire if abused.

Neil

Edited By Neil Wyatt on 27/06/2021 13:32:21