adding indicator to show charge complete

[aruna1]

guys I'm using following circuit to charge my 12V 1500mAh NiMH battery.(with 230V --> 15v step down transformer and a rectifier bridge)
is there any way i can put a indicator led or something to indicate charge complete status? (very simple circuit will be great).i was thinking if i put a series LED with battery will it go off once battery is fully charged?
thanks

[waltr]

That circuit can charge a NiMH battery but not properly and could damage the battery or at least greatly decrease its life span. There also is not a way to determine batery charge state with that circuit.

Check Panasonic's app note on NiMH charging methods:
http://www.panasonic.com/industrial/battery/oem/chem/nicmet/index.html

Here is a DIY NiMH charger:
http://www.angelfire.com/electronic/hayles/charge1.html
More info:
http://www.mpoweruk.com/chargers.htm
http://www.physicsforums.com/showthread.php?p=2487241

[aruna1]

Thanks I'll chk

[aruna1]

I was thinking will following circuit will work as automatic cutoff system when battery is fully charged?

initially optocoupler is off.we press S1 to turn on optocoupler hence powering up the circuit and begin charging the battery.as long as current flow through output of op amp will be high and optocoupler remains turned on.when battery is fully charged current flow through RL will be zero,therefore voltage difference between inverting input and non-inverting input of op amp becomes zero.this will turn off the optocoupler.and it will also cut power to entire circuit.

[Soeren]

Hi,

I was thinking will following circuit will work as automatic cutoff system when battery is fully charged?

Problem is, you can't charge like that, as you have no regulation.
Mains voltage can swing quite a bit and without regulation, so will the cutoff point and soon you have a ruined battery.

This charger will do for charging them. It's not a top notch quick charger, but will get your 10 cells charged without damaging them.

[aruna1]

I'm thinking about designing a smart charger based on 12F675