Hope someone can give me a quick answer to this one.
Can an old battery charger designed to recharge Ni-Cads be used to recharge Ni-MH cells?
I've got a dedicated charger for my little AAs but not the big D cells I want to charge.
Thanks for any help and happy New Year.
Rob
Probably best not to, mine has a switch to set NiMH or NiCd, which presumably it wouldn't have if it didn't need it, I think NiMH cells need (or benefit from) delta-V monitoring while charging to avoid overcooking them, buy yourself an Ansmann Energy 8 ...
On the cheapo one I have, the NiMH / NiCd switch sets the built in timer to
3 or 5 hours (NiMH being higher capacity). Of course, looking at the charging rate, it may need 8-10 hours on the latest NiMH cells. The old one the OP refers to will charge NiMH, but he will have to work out the charge time.I have a cheapo delta-V charger (£10) that cuts off when all 4 cells are charged (or never if one cell is duff), so best to buy one with individual delta-V (£25-30), which I assume the Ansmann one is. One with a fan would be nice too.
Bob
The "DigiSpeed 4" does individual deltaV and has a cooling fan, but only =
takes AA or AAA, the "Energy 8" takes C/D/PP3 too, but doesn't have a=20 fan ...
"NO"
that should read "YES" and "NO" all depends on charge rate
have a look at
john
Indeed. Under trickle charging, both types of nickel technology will tolreate being left on trickle essentially forever.
On fast charging its conventional to detect when the voltage at a given charge current DECREASES, and switch off, or to trickle mode, at this point.
This 'Delta V' is quite large - 20-50-mV - on NiCd but much lest -3-8mV IIRC - on NiMh.
Also, while it is safe to charge NiCd at up to three times the capacity (in mA/h) in mA (i.e. charge a 1000mA/h cell at 3A -and I've gine to 5 or 6 times without damage) its not good to charge most NiMh at more than its capacity - I.e.an 1100 cell should be charged at 1.1A or less.
So you can see that whilst a good adjustable fast charger that is built for both CAN charge both, and a trickle charger certainly can, a cheap fast charger designed for NiCd may well not be suitable for NiMh.
No knowing what charge rate you are aiming for, or what charger or cells you have,its impossible to give a shorter answer than that I am afraid.
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