A different conflict between charging systems

[booster]

There has been a bunch of discussion here about charging components that don't play well together, and there was just another example on the Yahoo board, but in a system that I really wouldn't have expected it in.

Condensed version. OP has an older Roadtrek, upgraded Progressive Dynamics 35 amp charger with Wizard, 100 watts of solar through a Sunsaver 15 MPPT Morningstar controller, Trimetric meter, isolator at engine not separator. Before solar did pretty well on the one battery (LP frig), better after solar, most days refilling to full on the battery

OP was off grid in an area that was very cloudy, poor solar, for days in a row, and Trimetric never got back to full. They ran the generator, which put very little amperage into the battery a if the battery was full, but it still never showed full. Much testing later, it was determined that the PD converter was putting out slightly low volatage at something like 14.2 volts. Plenty to fill the battery, though, but not enough to pass full battery threshold setting on the Trimetric, which was set at 14.3 volts. Battery was full, but nobody knew it because the Trimetric didn't say so, because the voltage was too low to reset it to full 100%. They drove the van, the voltage came up, and the Trimetric reset. Things back to normal, except for the charge voltage. Normally, they wouldn't have had this issue because the solar would have gotten the voltage high enough for the Trimetric reset.

That was the minor component miscommunication. Along the way, the not real easy to get to battery was accessed to do a specific gravity test to see if it was really full, and the OP found it very low on water. They had good history of water use, and it had not been anywhere near long enough, in their opinion, to be down so far. The only real thing that had changed was that it was plugged in over the winter (in Ohio, I think) continuously, with the relatively new solar in place. The leading speculation is that the PD converter was at storage voltage of 13.2, on a full battery from being charged up after being plugged in. There were no power drains other than the solar controller and such, so very low. Speculation, which is probably correct, is that the solar, which will run a full, timed absorption at every day/night cycle was putting too much extra charge voltage, too often, on a full battery. I think the Morningstar does something like 4 hours of absorption every day, so that is a lot on a full battery. It is also temp compensated, so the 14.4 setpoint would be boosted up in the winter cold (properly) making it charge much more than the PD would, without temp comp. They have a lot of solar compared to battery, so the problem would be more evident with them that with others who have a lower ratio. The OP is in the process of adding an on/off switch to the solar, so it can be shut off when on the charger long term.

I would not have thought that they would have a problem, as the PD goes into charge for a fixed time every plug in cycle, so the solar wouldn't mess up its charging of the batteries, and that has been where the conflicts have been seen. It never occurred to me that the solar, because it does not sense a full battery in any way, at startup, would be able to dry out a battery like that. It does make sense though, now that it is actually seen. You could easily have over 100 full charge cycles put on top of the full battery, in the span of a winter.

It just seems to reinforce the idea that certain components work best under certain conditions, and other components can mess them up, or the other way around. It is looking more and more like, in lieu of a very sophisticated control availability, separate turn on/off on most of this stuff is a good idea, so you can take care of the odd/ unusual times, or optimize when you want to. It also points out the hazard of relying on the Trimetric for all the information. It is a good item, but it too can be fooled. The folks in this example won't need to shut off the solar all the time, but probably should sometimes, if the theory is correct.

[markopolo]

Like you mentioned, I wonder if the end of winter results would have been different with two or three batteries etc. instead of one battery........

In hindsight, with that high of a ratio of solar to battery, there probably was no need to plug in for the winter. Or plug in for the winter but install a switch to shut of solar input.

Every setup is unique That was interesting to learn - not something I would have thought of.

[Bugsy White]

I have got a lot to learn about charging systems and designs, electrics, batteries, and set-ups...( im creeping through all of the forum topics and trying to read up on all of you guy's set-ups and what ya'll use )