I have written code for a fairly simple PWM charge controller, in C for PIC16F886. I have ADC inputs to measure both the battery and panel voltage with LCD display. It also incorporates 4 set points, voltage reg, array reconnect point, low voltage disconnect and load reconnect. I was originally making this a simple On-Off type controller but since moving to PWM I believe I can remove the array reconnect point as the PWM pulse width should take care of this (array can always be connected). Maybe I can add a safety point so the PWM turns off completely if the battery reaches some voltage.
I understand the basic principle, such that the PWM is essentially always on when the battery voltage is low and is only on slightly as a trickle charge when the battery is at the voltage regulation set point.
Where I am getting stopped is what is done inbetween? I cannot find any information on how quickly the pulse width should decrease or increase. I take it this is probably the proprietary information within commercial PWM charge controllers. On the battery charging, at what point do I begin to reduce the PWM pulse from full on? What PWM duty cycle is used for a trickle charge ususally? I suppose you would want the PWM on for the longest time possible to do as much charging as possible.
I am using a home made solar panel, Voc ~19V and Isc ~3A. I've got an old car battery, sealed lead-acid, for my storage.
Eventually I'd like to progress this into a MPPT type charge controller, but I figured it would be more beneficial to start with a PWM type.
All thoughts, comments appreciated!
I understand the basic principle, such that the PWM is essentially always on when the battery voltage is low and is only on slightly as a trickle charge when the battery is at the voltage regulation set point.
Where I am getting stopped is what is done inbetween? I cannot find any information on how quickly the pulse width should decrease or increase. I take it this is probably the proprietary information within commercial PWM charge controllers. On the battery charging, at what point do I begin to reduce the PWM pulse from full on? What PWM duty cycle is used for a trickle charge ususally? I suppose you would want the PWM on for the longest time possible to do as much charging as possible.
I am using a home made solar panel, Voc ~19V and Isc ~3A. I've got an old car battery, sealed lead-acid, for my storage.
Eventually I'd like to progress this into a MPPT type charge controller, but I figured it would be more beneficial to start with a PWM type.
All thoughts, comments appreciated!