Lead acid battery charger with DC input

Thread Starter

Zoubair Oudrhiri

Joined Feb 7, 2018
1
hello,
I'm new here this is my first post :D, i'm working on a project on a how to charge a 12v lead acid battery with a 12v power supply (2 separate cells), i have already found a way to amplify the voltage to 14.5 volts, but i spent 2 days looking for a way to limit the current output to 1A for a slow charge (it doesn't matter how slow)
Can you please help me
Thanks
 

crutschow

Joined Mar 14, 2008
34,280
Below is the LTspice simulation of a simple current-limit circuit that should do what you want.
The battery current (yellow trace) stays at near 1A until the battery voltage (green trace) gets to ≈13.7V, at which point it linearly falls to zero as the battery reaches 14.5V.

R1 needs to be a 1W resistor.
Its value determines the current limit which is ≈0.7V/R1.

The P-MOSFET can be just about any in a TO-220 case, since it can dissipate up to several watts (red trace) and needs to be mounted on a small heat-sink.

upload_2018-2-13_12-14-6.png
 

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