Just wondering, Ni-cd charger used on Ni-mh

[Syntax]

I know it is not the right place to ask, but maybe some of you know the
answer.
I got a bunch of Ni-mh batteries, and a charger that supports normal and
Ni-cd charging, so what charging method is the best for these batteries?

Puuuf, there goes my brain

Wkr Syntax

 

[Larry]

I know it is not the right place to ask, but maybe some of you know the
answer.
I got a bunch of Ni-mh batteries, and a charger that supports normal and
Ni-cd charging, so what charging method is the best for these batteries?

Puuuf, there goes my brain

Wkr Syntax

Set the charger to charge NiCd batteries and it will charge the NiMh just
fine...albeit a little slowly as they are probably much larger in AH
capacity. I'm currently buying NiMh "AA" cells at 2.5 AH!

Larry

 

[Syntax]

Set the charger to charge NiCd batteries and it will charge the NiMh just
fine...albeit a little slowly as they are probably much larger in AH
capacity. I'm currently buying NiMh "AA" cells at 2.5 AH!

Larry

Okay, now i know it is safe to use.

Mine are 2 and 2.5 AH, but they actually take less time to charge on the
Ni-MH setting than on the normal setting.

But thanx.

Wkr

Syntax

 

[Larry]

Mine are 2 and 2.5 AH, but they actually take less time to charge on the
Ni-MH setting than on the normal setting.

Yes. The NiMH setting charges at a higher current. Ni-Cd chargers will
charge them, but at the slower rate...which isn't a bad thing at all.

Larry
--

 

[Meindert Sprang]

Yes. The NiMH setting charges at a higher current. Ni-Cd chargers will
charge them, but at the slower rate...which isn't a bad thing at all.

You have to be carefull though. NiCD is usually charged either at C/10 rate
of at high current, where a drop in voltage is used to detect the end of the
charging cycle.

The C/10 charge with NiCD cannot overcharge them.

However, NiMH batteries show a much smaller voltage drop when full, which
might not be detected by a fast NiCD charger. Also, overcharging NiMH at
C/10 will certainly damage them. So be careful!

Meindert

 

[Jack Erbes]

Meindert Sprang wrote:

You have to be carefull though. NiCD is usually charged either at C/10 rate
of at high current, where a drop in voltage is used to detect the end of the
charging cycle.

The C/10 charge with NiCD cannot overcharge them.

However, NiMH batteries show a much smaller voltage drop when full, which
might not be detected by a fast NiCD charger. Also, overcharging NiMH at
C/10 will certainly damage them. So be careful!

Meindert

So for routine purposes and otherwise healthy NiMH cells, what would you
use? As an aside, I finally figured out that C/10 means 1/10th of
capacity and that C/20 or C/30 is a much better idea.

I have a DuraCell quick charger that is identified as a "Class 2"
charger but does not tell me much more than that. Do you know what the
charge rate on a Class 2 charger is? Output is 1.6V @ 1800mA.

I'm about to throw away the DuraCell and get a Maha I think.

Jack

 

[Meindert Sprang]

So for routine purposes and otherwise healthy NiMH cells, what would you
use? As an aside, I finally figured out that C/10 means 1/10th of
capacity and that C/20 or C/30 is a much better idea.

I must corrent myself here. C/10 is fine for NiMH. Faster than C/10 will
overcharge them when not stopped.

I have a DuraCell quick charger that is identified as a "Class 2"
charger but does not tell me much more than that. Do you know what the
charge rate on a Class 2 charger is? Output is 1.6V @ 1800mA.

No idea but the specs suggest that it pumps 1800mA in the cells. The
efficiency of NiMH is 66% so when you have a 2500mAh cell, it needs
2500/0.66 = 3800mAh for a full charge. That equals 3800/1800 = 2.1 hrs with
your charger. So to see if your charger works, put the empty cells in, and
check after 2.1 hrs if the charger has shut off of does so within the next
15 minutes or so. If it doesn't, disconnect it yourself.

Meindert

 

[Jack Erbes]

I must corrent myself here. C/10 is fine for NiMH. Faster than C/10 will
overcharge them when not stopped.




No idea but the specs suggest that it pumps 1800mA in the cells. The
efficiency of NiMH is 66% so when you have a 2500mAh cell, it needs
2500/0.66 = 3800mAh for a full charge. That equals 3800/1800 = 2.1 hrs with
your charger. So to see if your charger works, put the empty cells in, and
check after 2.1 hrs if the charger has shut off of does so within the next
15 minutes or so. If it doesn't, disconnect it yourself.

Thanks Meindert,

The cells I have a Energizer NiMH 2300mAh AA's. They have been charged
a couple of times now. The DuraCell quick charger charged them in about
15-20 minutes (blinking LED stopped blinking) on the first use, it took
more like an hour after the second use.

The batteries show a stable 1.37V aftet they are charged, removed from
the charger, and rested for a day or so. I haven't checked to see what
they come off the charger at, I need to do that though.

But the thing irritates me a little because I have no idea what it is
doing and no control over anything. I think I'll treat myself to a
better charger and feel a little better for better just for knowing what
is going on there.

I don't use a lot of batteries and am more interested in getting a good
charge that will provide longer service life on things like my Garmin
76Cx handheld than I am in getting fast charges.

I decided to try the NiMH's for awhile simply because I think it is
better for world in the long run, I don't think it will save me any
money in the long run over the 35 cents or so I pay for the disposable
alkalines I have been using. I'm probably wrong about that too though.

Jack