Simple Charger for 12V Lead-Acid Batteries

[bountyhunter]

There seems to be some interest in charging 12V lead acid batteries. I will attach a design I did for smaller lead acid batteries (like 20 A-hr or less capacity) which is an easy project to build. It has temperature compensation so it can be left attached to a battery in the garage (I use it for my motorcycle). It lights an LED when the battery is fully charged. The article explains all the circuit operation.

No heatsinks required, power source is a 12V wall cube.

This info was published in an article I wrote for EDN magazine a long time back so it is public domain now (you can use all you want).

 

[Boncuk]

Hi,

your circuits looks neat and simple.

Here's a neat and simple PCB design for it.

 

[bountyhunter]

Hi,

your circuits looks neat and simple.

Here's a neat and simple PCB design for it.

Very cool. Your PCB software is really fast.

 

[Boncuk]

Very cool. Your PCB software is really fast.

It's not the software, it's the operator.

BTW, I suggest making a note about the LED types to use. They must be low current (2mA).

Since R12 (full charge) has a value of 3.3K I adapted R15 to have the same value (power LED). All other values are unchanged.

 

[Mr RB]

Any reason for using 10 1N4148 diodes?? (sorry i didn't download the read the article)

 

[MikeMl]

Any reason for using 10 1N4148 diodes?? (sorry i didn't download the read the article)

Temp compensation.

 

[microtexan]

Battery Charger PCB

It's not the software, it's the operator.

BTW, I suggest making a note about the LED types to use. They must be low current (2mA).

Since R12 (full charge) has a value of 3.3K I adapted R15 to have the same value (power LED). All other values are unchanged.

Boncuk, is there a way to print the PCB design without the parts overlay to make an etching pattern?

Thanks

 

[bountyhunter]

Any reason for using 10 1N4148 diodes?? (sorry i didn't download the read the article)

They are for temperature compensation. A lead acid battery has a tempco, so it's best if the charger matches it.

 

[Boncuk]

Boncuk, is there a way to print the PCB design without the parts overlay to make an etching pattern?

Thanks

Just PM me your email address to get the Eagle files (schematic + PCB layout)

Regards

Boncuk

 

[gie_lostdream]

please,
i'm so confused about "wall transformer"
what is "wall transformer" ?
can someone help me, with schematic diagram of wall transformer..

 

[crutschow]

please,
i'm so confused about "wall transformer"
what is "wall transformer" ?
can someone help me, with schematic diagram of wall transformer..

It's simply a transformer (or more commonly a DC supply) that plugs into a wall AC outlet. Also often called a wall-wart.

 

[OlPhart]

Battery Maintenance

Here's my flavor. While not as elegant as BHs', its' intent is not to charge but hold a battery over long idle times. Current record is over 2 years on a motorcycle that got parked & forgotten. Carbs were totally plugged, but the AGM battery was fine.

One wall wart & regulator can feed Several diode + resistor outputs (mine has 8). I've build at least 6 of these for friends' motorcycles & garden tractors. <<<)))

 

[gie_lostdream]

Here's my flavor. While not as elegant as BHs', its' intent is not to charge but hold a battery over long idle times. Current record is over 2 years on a motorcycle that got parked & forgotten. Carbs were totally plugged, but the AGM battery was fine.

One wall wart & regulator can feed Several diode + resistor outputs (mine has 8). I've build at least 6 of these for friends' motorcycles & garden tractors. <<<)))

is this schematic can work for Simple Charger for 12V Lead-Acid Batteries