Yet Another PWM vs MPPT Comparison Test

BFL13 wrote:

NinerBikes wrote:

BFL13 wrote:

greenrvgreen wrote:
IMO, a "real world test" must be done with a load on the batts equal or GREATER than the capability of the panels. AFAIK, I've never "recharged" my batteries, but I'm constantly in the process of trying to replace what I'm constantly taking.

+1 on the PWM with 12v panels. I was surprised by how efficient that combo is.

You will note in the OP that the 12.2 volt test was done with battery loaded. Had over 100a load compared with about 24a in from solar. You still have to wait until the 100a or whatever load takes the battery voltage back down to the level you want to measure MPPT performance at.

You can do "replacement" every day and get however close to full each day that gets you, depending on the weather etc. Every so often you must do a full 100% "overcharge" (equalization type of charge works for this) or your batts will get sulfated permanently losing some capacity.

Various techniques available for doing that, including by-passing the controller with a "split bank" method if still camping.

You CAN only do the bypassing and split banking if you have 12V panels that run at a Vsc of 17 to 17.5... the goal being to get the equalization voltage at the battery either up to 16.0V, or your Specific Gravity up to 1.280 or thereabouts, depending on what your baseline new battery SG was.

I see no reason you cannot by-pass the MPPT controller and use 24v panel direct. It can only do its Isc of say 8.3a. I have not tried it though. Perhaps the battery voltage would rise too high before the SG got up there?

The 12v panel voltage in the 17s is the Vmp, which means nothing to PWM, but is important for MPPT. 12v panel Voc can be important where you sometimes see ratings in the 22s instead of 21s for the same wattage, which leaves the Isc lower than usual. You want highest Isc per watt for your panel dollar with PWM.