mppt vs pwm

red31 wrote:
My shunt controller had a frequency of ~ 1 day. It stopped at 14.2v and came back on at 13.0v. If it stopped early enough in the day, it might come back on but with a small panel, it likely never reach 14.2v by sunset.

Yes there is enormous confusion about On/Off as the definition of "shunt" vs "series" where amps taper with a constant voltage.

My ASC did do on/off. But it had that varying "duration" of the "pulses" so they called it Low Frequency PWM" not "Shunt"

With that running after it started "controlling" in the afternoon once the batts had reached the set Vabs, you could see on the Trimetric that when it went "off" both voltage and amps fell, then came back up when it turned back "on" At first this was very rapid and made you dizzy. Later it was not so rapid and the amps reached when on were lower.

Let's call that my new term, "Modified Shunt"

Next I got an EP Solar LandStar "Series" type PWM controller. On the Trimetric, this one did not make you dizzy on the voltage reading, which stayed constant, but the amps went up and down a lot becoming less and less each time. That was the "tapering" Not a steady decline really like a tapering converter in Absprption, but that was the idea instead of varying the duration of on and off.

I think the suggestion is that by turning right off each time, the battery might like the little kick start with the total on and off each time better than the smoother Series method?

It is all very obscure and terminology variance is no help. Some of it may even be ( my favourite!) "proprietorial" so we'll never know among Brands. :(

I was just as happy with my ASC and with the LandStar as to how they got the batteries done up each day each with its own version of "tapering amps" during Absorption.

I sure would not have been happy with a strict Shunt type that got to the "high set-point" and then let go till Vbatt got down to the
"low set-point" and then got going again.