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

Kalico wrote:

Can an old battery charger designed to recharge Ni-Cads be used to
recharge Ni-MH cells?

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 ...

Kalico wrote:

Can an old battery charger designed to recharge Ni-Cads be used to
recharge Ni-MH cells?

http://www.greenbatteries.com/bachfa...%20differences

caveat secuutus

"Andy Burns" wrote in message
...
Kalico wrote:

Can an old battery charger designed to recharge Ni-Cads be used to
recharge Ni-MH cells?

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

"Kalico" wrote in message
...
Hope someone can give me a quick answer to this one.


"NO"

"ian s" wrote in message
...

"Kalico" wrote in message
...
Hope someone can give me a quick answer to this one.


"NO"

that should read "YES" and "NO" all depends on charge rate

Andy Burns wrote:
Kalico wrote:

Can an old battery charger designed to recharge Ni-Cads be used to
recharge Ni-MH cells?


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 ...


have a look at
http://www.powerstream.com/NiMH.htm

they recommend charging NiMH cells to 1.41 volts at 20 deg. C. so long
as the charge rate is less than C/10.

john

On Sun, 01 Jan 2006 11:46:23 GMT, Mr Fixit wrote:

"ian s" wrote in message
...

"Kalico" wrote in message
...
Hope someone can give me a quick answer to this one.


"NO"

that should read "YES" and "NO" all depends on charge rate


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.