Old Radio Shack Charger Questions

[Hitthespot]

My father was cleaning out some old items today when he came across this old Radio Shack Charger. Model 23-334. He asked me if I wanted it because he no longer had a use for it, and he never had good luck with the batteries he charged in it. I seen the batteries before he threw them out they were old Ni-cad batteries. I told him I would take it and do some research and see if it was still useful.

The reason this charger worries me is because it does not list any kind of automatic circuits. It just says it has a safty timer shut off to prevent the batteries from overcharging. I list the specifications below but I guess I have a couple of questions.

1) Will this charger charge modern Ni-MH batteries to the correct capacity.
2) Is this charger safe to use on modern batteries when it does not seem to have any kind of auto shut off? How would it detect a half charged battery and shut off accordingly?

-has a switch for Ni-Cd / Ni-Mh
-charging current Ni-MH
AAA 65ma
AA 150ma
C,D 270ma
9V 23ma
-charging current Ni-CD
AAA 30ma
AA 100ma
C,D 230ma
9V 23ma

Protection Timer 14-15.5 hours AA, AAA
18-20 hours C, D

Thanks

Bil

 

[SilverFox]

Hello Bill,

To use that charger, you would first have to make sure to discharge your cells. It terminates the charge after the time limit has been reached. If you put a half charged cell into it, it will overcharge it.

Some rough calculations for the NiMh charging rates suggest it would be good for

1600 mAh AA cells
650 mAh AAA cells
4000 mAh C cells and
4000 mAh D cells.

The 9V setting looks good.

Tom

 

[Hitthespot]

Thanks Tom,

EDITED: PM Sent

Bill

 

[Mr Happy]

When you do a forming charge with the C9000 the 0.1C/16 hour charge rate typically works out in the range of 160 - 250 mA for AA cells, so the 150 mA rate on this charger doesn't seem likely to do much harm, especially if the cells are empty before charging.

Even if not used for regular charging, it might be a convenient way to do a slow forming charge occasionally on cells to rejuvenate them?