12V AGM lead acid battery charging with PWM charge controller-How to create the PWM signal?

Thread Starter

jim0000

Joined Oct 28, 2020
32
I am trying to create a PWM signal to charge a 12V AGM lead acid battery from a 100W solar panel. Of course the charge controller has multiple functions depending on the charge of the battery but I am kind of stuck at initially creating the PWM signal itself. Is there a typical method used? I've only ever used a 555 timer to create a pwm signal, but I haven't noticed any 555 timers so far in pwm charge controller circuit designs. I see that sometimes transistors are used, and sometimes a configuration of capacitors and resistors and diodes. Also, does frequency matter?
 
Last edited:

Alec_t

Joined Sep 17, 2013
12,315
I haven't noticed any 555 timers so far in pwm charge controller circuit designs.
I suspect that's because in a charge controller these days, a single micro-controller would be used to generate not only any PWM signal required but also to do all the other housekeeping tasks necessary in the control process.
 

Thread Starter

jim0000

Joined Oct 28, 2020
32
I suspect that's because in a charge controller these days, a single micro-controller would be used to generate not only any PWM signal required but also to do all the other housekeeping tasks necessary in the control process.
Well yeah MPPT controllers are definitely more popular now. I just don't know how to program a microcontroller so I am wanting to make a PWM controller.
 

Ian0

Joined Aug 7, 2020
3,760
If you can't do a MPPT by the usual Perturb & Observe, or impedance methods, then regulate the panel voltage - the voltage at which peak power occurs changes very little with light intensity, but you will have to temperature compensate as it varies considerably with temperature.
 
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