Is there any danger in charging fractional batts?

I spoke with a guy at TNR Technical today and ordered some 1/3AAA batteries.
He said that I shouldn't use a standard charger or a fast charger because they would overheat the smaller (fractional) batteries.
Is there any truth to this or does everybody use fast chargers for their 1/4, 1/3, 2/3 cells?---Marc

It makes sense that it might overheat them when charged individually (Not when charged in a pack though) because they have less surface area.

Originally posted by MicroE:
I spoke with a guy at TNR Technical today and ordered some 1/3AAA batteries.
He said that I shouldn't use a standard charger or a fast charger because they would overheat the smaller (fractional) batteries.
Is there any truth to this or does everybody use fast chargers for their 1/4, 1/3, 2/3 cells?---Marc

Click to expand...

<font size="2" face="Verdana, Arial">Just buy a small inexpensive constant current charger and rheostat (using a lamp dimmer) the current down to 10-15mA.

When you 'fast charge' an NiMH, you are feeding it something like 1/2C to C rate current. (C rate is a current equal to the mAh capacity of the cell.) Most fast chargers have a fixed current rate, and if you somehow connect smaller cells, then you are going to be charging them at much higher currents than they are rated for. A 1/3AAA cell probably has a capacity of about 150mAh. Charging them with a fast charger designed to dump 1500mA into a full sized AA cell will probably toast them.

If you can properly adjust the current, then 'fast charging' these smaller cells at an appropriate lower current should be just fine.

-Jon

Originally posted by MicroE:
I spoke with a guy at TNR Technical today and ordered some 1/3AAA batteries.
He said that I shouldn't use a standard charger or a fast charger because they would overheat the smaller (fractional) batteries.
Is there any truth to this or does everybody use fast chargers for their 1/4, 1/3, 2/3 cells?---Marc

Click to expand...

<font size="2" face="Verdana, Arial">I am assumeing NiMH cells here.

I think you can get away with it if you use an overnight charger that does AAAs.

A AAA is around 700mAh and the 1/3AA cells are around 250mAh to 400mAh. So I think an overnight charger for AAAs will be like a fast charger for 1/3 AAs

My last post should have specified 30-50 mA..I mistakenly read AAA instead of AA.