How hot should NiMH's get in the charger

 

New subscriber here.

I have a set of Sony AA size NiMH's that are the original batteries
which came with the charger. Upon charging for a couple hours, they
are almost too hot to hold in my hand.

Normal? Safe? Advice?

Second question: Is there any reason to fear using other brands of
NiMH's in the same charger?

 

Bearded Occam wrote:

In my opinion, charging batteries so fast that they get that
hot cannot be optimal for the life of the batteries.


I would be worried about charging any batteries in that charger.

I like the Maha MH-C401FS 100 containing 4 independent
chargers with a fast charge/slow charge switch.  I always
use the slow charge.  The cells get just a little above body
temperature at the end of the charge cycle.
http://www.mahaenergy.com/store/viewItem.asp?idProduct=178

 

On Sun, 22 Jul 2007 20:07:09 +0000, Bearded Occam wrote:


Not normal or safe.

 


if they can be held tightly without causing blisters that's fairly normal


no.

Bye.
   Jasen

 

Jasen Betts wrote:


Fast (one hour) charger using temperature rising and negative voltage
slope coming from heating to detect end of fast charge and going to low
charging current. Temperature rising begun around 80% charge state.

Using temperature rising was standard methode to charging NiCd-packs in
many proffesional equipment and using simple thermostate or PTS-resistor
inside pack to cut down charging - batteries was pretty heat in this
case, and negative delta voltage detect is later invent from 1980 or
so.. days modern fast charger using both metodes.

Hot batteries (~ 50 degree C) is normal for fast charger even to days
NiMh-charging, but don't use NiMH batteries in NiCd-charger - NiMh have
lot lower negative voltage slope compare to NiCd-batterier and NiMH in
NiCd fast charger mode, ends fast charging more or less to late for NiMh
and wears out very fast in this case...

/TE