Using NiCd charger on NiMh battery?

[woodchips]

Have a very old Makita 18V 8390 drill using the original 1.3Ah NiCd batteries. The chargers all say they will cope with multiple voltages and also NiMh cells. Asked Makita and no reply, as usual.

If I recell the battery, do I have to connect the currently unused terminal inside the charger to the battery? If so where? What happens if I don't?

Snag is the cost of NiCd or NiMh cells makes re-celling these batteries uneconomic. The NiMh cells came out of some old test gear, they will take a charge but not tried a whole battery full of them. I changed the cells to a Bosch 18V 1.5Ah or 2Ah lithium battery that plugs in, remove to charge in the Bosch charger. At £20 each these were by far the cheapest 18V batteries I found.

The drills are all perfectly ok, done an immense amount of work in 15+ years and I am seriously irritated that Makita changed the battery style to force me to buy a new, unwanted, drill. Note that Ryobi didn't with there one+ series.

Thanks.

[David Hess]

If a NiCd charger uses negative deltaV to detect charge termination, then it will overcharge and damage a NiMH battery.  But I have noticed that many NiMH power tool chargers use temperature rise of the cells to terminate charging and that may work if you change the batteries from NiCd to NiMH.  It is still pretty hard on the batteries though.

[Haenk]

I have one Mafell/Milwaukee drill, that came with NiCd, but the carger stated "NiCd/NiMH", so I replaced the original NiCds by 3rd party NiMH - works flawless (bith charger and drill), though has a bit less power it seems (probably less peak Ampere).
If it's printed on the charger, you are good to go, I'd say. (They won't print that on without a reason...)