Hi, i wanted to use the attached circuit as an intelligent NiCad battery charger. However, i am contemplating changing the NiCad battery to a sealed lead acid (SLA), because my research indicates that they are more suitable for float charging. The battery is to be used as a backup power supply, so it will constantly be within the circuit.

My question is can i modify the circuit to work for an SLA battery. As far as i understand, would be altering the constant current source to a constant voltage source be sufficient?

What else would i need to take into consideration?

 

A lead-acid float charger does not need any intelligence, just a constant voltage (typically 13.8V per '12V' battery) and current limit to prevent damage when the charger is powered and the battery is dead or very low.

The maximum current is in the battery specs, but any lower current is fine.

 

True.. You are throwing too much at a led-acid floater. They are very easy. Also, regarding the schematic, we would have no idea of the code in the PIC so, it could actually do MANY things. It appears the pic is just being used as a PWM source, which is overkill to the NTh degree. It could be done with a 555.

There are literally hundreds od lead-acid charger circuits available. With the popularity of DIY wind and solar power, this is a very popular topic. There are also charger ICs which would cut down the component count.

But for $30us you can get a battery tender that also has a desulfinator circuit built in. I am using these for a desulfinator experiment I am doing.. They work well and cover two things in one box.