Simple battery charger question???

[dog812]

I have a really basic 4 x AA battery charger for 6 (4.8) volt 100 ma...
But i only need to charge 3 AA batterys for 4.5 (3.6) Volts.

Can i put a resistor on the power line coming out of the battery charger to bring it down to 3.6? or will it still fill my batterys to 4.8 volt?

 

[audioguru]

A good Ni-Cad or Ni-MH battery charger senses the battery voltage then does not overcharge an already charged battery.
Then it uses a fairly high current to quickly charge.
Then it senses that the battery is fully charged and turns off.

A simple battery charger overcharges batteries that reduces their life.

Your 3 AA cells will be overcharged by the 6V supply unless you somehow determine that they are fully charged and remove them.
A series resistor reduces the current, not the voltage.

 

[dog812]

Ok.. makes sence..
My batery charger is really basic.

 

[MrAl]

Hi there,


I used to use a battery charger that would do 4 cells, but would do
two at a time so i couldnt put in only one battery. What i did was
connected two 1N4001 diodes in series and used that to replace
one cell. Thus, i could put in one cell and one 'fake' cell made from
the two diodes and charge only one battery.
The diodes have a relatively constant voltage at the constant
current of the battery charger (NiMH that is) so it works ok with
some chargers. Some chargers are more picky so it wont work.

It's best to get a better charger however, that can do only
one cell if you need that. This way you can easily charge
1, 2, 3, or all 4 cells, as many as you need.

Energizer and Duracell make 15 minute chargers which arent too bad.