[KellyClarksonTV]

I've notice black stains in the charge contacts in my battery charger appear
from time to time. They are easy to clean off, but I'd like to know why that
happens. Thanks.

 

[Robert Baer]

I've notice black stains in the charge contacts in my battery charger appear
from time to time. They are easy to clean off, but I'd like to know why that
happens. Thanks.

Most small cells ("batteries") that are charged, use an alkaline-based
paste for the electrolyte.
Overcharging builds up pressure insiide, and a small amount leaks out
- mostly in gaseous form.
Most metals corrode in such surroundings - take the case of corrosion
near saltwater...

 

[KellyClarksonTV]

Thanks. I'm actually very careful about overcharging. I always use them until
they're "flat" (won't run a CD player, digital camera, etc) and conservatively
charge only 80% of the charge time. Any other reason for the rust?

 

[Robert Baer]

Thanks. I'm actually very careful about overcharging. I always use them until
they're "flat" (won't run a CD player, digital camera, etc) and conservatively
charge only 80% of the charge time. Any other reason for the rust?

Some cells, as they get old, also tend to leak a little.
Not a lot can be done, except clean the contacts on a regular basis,
and look at the negative contact of each cell, for any "white stuff"
(either clean off or toss cell).