this is similar to previous... if a device has a built in 3.6 rechargable
battery and it says to not charge it onboard with a power supply that exceeds 200 ma...5v.....I thought that any wart 4.5-6 with at least 200 ma is ok.
do you think that they were wrong or what??? why would they say that??

 

I would tend to take the manufacturer's word for it. Certainly not to exceed the stated maximum voltage. No wall wart regulates well enough to really trust the label, unless you feel like living dangerously.

 

what I meant is the battery will just take what it needs and no more ,right?
I thought that was the way it worked....

 

Heh. No. http://www.batteryuniversity.com/

You usually need more sophisticated charging circuits for modern rechargables.

 

However, you can make one battery recharger based on an op-amp (as a comparator) to monitor the voltage on the battery terminals. You need a transistor in series with a resistor so you can control the current going to the battery (you must always limit the current).

 

What sort of battery..? 3 x NiMH ?? 3 x NiCd ??? 1 x Lithium Ion.. ????

Capacity... ???