Solar help... Mppt or PWM
Hi.. I recently got a new solar panel from somewhere... fell off truck... lol I know mppt is the way to go im mysituation but am asking for advice... panel 250 watts volts 30v. Wh...
Forum Discussion
I wouldn't keep it in Absorb more than 1.5 hours.
Your logic for Absorb time mirroring the Bulk time makes sense, but very little. The time it takes to hit Abs voltage is a poor indicator, it varies a lot depending on how sunny it is, or what loads you're running in those first few hours.
Absorb time should be based either on starting open-circuit voltage OR on the current at the end of the Absorb time, ex, current drops to 1A if fridge and other loads are not running at that moment. This is how it's done in more expensive controllers, - it terminates or shortens the Abs stage based on either of two parameters. If you have plenty of time on your hands, watch the current and switch to Float.
Mid-range controllers typically have a fixed Abs time 60-90 minutes, and you can also do it this way - fixed Abs time. Twist your kitchen timer to 60 when it hits 14.8.
Btw, I don't know where you got those 14.8V. Bulk voltage should be set according to your battery specs. Some batteries have 14.5, some 14.8. It will still be wrong voltage with your controller, no matter what, because these specs are for 77F only. At higher temps volts should be reduced, at low temps - increased.
Your logic for Absorb time mirroring the Bulk time makes sense, but very little. The time it takes to hit Abs voltage is a poor indicator, it varies a lot depending on how sunny it is, or what loads you're running in those first few hours.
Absorb time should be based either on starting open-circuit voltage OR on the current at the end of the Absorb time, ex, current drops to 1A if fridge and other loads are not running at that moment. This is how it's done in more expensive controllers, - it terminates or shortens the Abs stage based on either of two parameters. If you have plenty of time on your hands, watch the current and switch to Float.
Mid-range controllers typically have a fixed Abs time 60-90 minutes, and you can also do it this way - fixed Abs time. Twist your kitchen timer to 60 when it hits 14.8.
Btw, I don't know where you got those 14.8V. Bulk voltage should be set according to your battery specs. Some batteries have 14.5, some 14.8. It will still be wrong voltage with your controller, no matter what, because these specs are for 77F only. At higher temps volts should be reduced, at low temps - increased.
