1.5 Volt Battery Charger

[RodneyB]

I am wanting to build a Battery charger for a 1.5 volt AA Battery. Can any one assist with a circuit diagram.

Best wishes

Rodney

 

[alec_t]

What type of battery (i.e. battery chemistry)? Not all types are chargeable. Those that are have different charging regimes. The most common '1.5V' cells are alkaline or zinc-carbon; neither of which is generally regarded as chargeable.

 

[RodneyB]

NiMh or NiCd Battery I will use 2 x 1.2 Volts And then regulate it down to 1.5 Volts so I need a circuit to charge these Batteries

 

[cowboybob]

Good to see you back, RodneyB!

So, let me get this straight:

You're using 2 x 1.2 VDC Nixx batteries (presumably in parallel to get 2.4VDC), whose output you are then regulating down to 1.5VDC. Is that correct?

And you the want a circuit to charge the 2.4VDC battery set, right? I ask because in your first post you asked for a 1.5VDC charger circuit.

In either case, Try GOOGLING "nicd battery charger circuit diagram" and take your pick...

We'd be glad to critique your selection and offer suggestions.

 

[alec_t]

Unless you're doing this simply as a learning experience it would be simpler/cheaper to buy a charger.

 

[picbits]

You're using 2 x 1.2 VDC Nixx batteries (presumably in parallel to get 2.4VDC),

Presumably in series

 

[cowboybob]

Presumably in series

Presumably, sometimes I've just gotta laugh at myself...

 

[audioguru]

The two battery cells will have a total voltage that drops to 2.0V so I hope you are using a "low-dropout' 1.5V voltage regulator.

 

[RodneyB]

I would be putting the 2 x 1.2 Volt NICAD batteries in series to get the 2.4 Volts then I will regulate it Down to 1.5 Volts, I am driving a clock which needs 1.5 Volts. So I am going to need to charge the batteries at 2.4 Volts then regulate to 1.5 Volts. The low drop out voltage regulator is the next challange

 

[audioguru]

A 1.2V Ni-Cad cell is close to 1.4V when it is fully charged. A discharged cell is 0V to 1.0V so the charger needs a current-limiter.

Ni-Cads are old fashioned and self-discharge quickly in 2 weeks to one month. Modern Ni-MH cells hold their charge for 1 year.

Lots of semiconductor manufacturers make 1.5V low dropout regulators.

 

[RodneyB]

Thank you for the advice, I will go and see what is available in our shops tomorrow and then continue with this project

 

[picbits]

What kind of clock is it ? If it's one which takes an AA battery and lasts a couple of years from that then you won't have much luck with NiCd and NiMh to be honest with you.

 

[alec_t]

Many digital clocks run happily from an AA cell until the volts drop to ~1V, so a single NiMH cell would probably do, providing it is a low self-discharge current type. Personally, I'd use an alkaline cell and forget the charger.