OK -- I realize that without an ammeter, I am playing a bit of a guessing game. But yes, the BatteryMinder keeps the battery at almost 100 percent state of charge, judging by the voltage after I unplug it (12.7).
So the solar panel (which is rated at 6.6 amps) is essentially trying to jam juice into a full battery, and it sounds like there is no immediate need to use the panel for that particular purpose in advance of a camping trip.
On our last trip, which was the first with these portable panels, the battery performed better than it ever had. It would end each afternoon around 13.9 volts. Then, we used our lights, and the heater, and the water pump. In the morning, the battery would be at about 12.6 or 12.5 volts, only to recharge during the day. So we had more than enough juice.
Without a solar panel, a battery would last about three days before dropping to 12.2 or 12.1, at which point we would swap it out for the spare battery. That meant that at least once a week, we would have to recharge, either with our generator or an an RV park (where we would have to dump the tanks, anyway). But with the panels, we have an essentially infinite supply of juice, as long as it is not too cloudy or shady.
Based on Mexicowanderer's comments, it sounds like there is a good reason to top charge the battery, and I am intrigued by the idea of bypassing the controller to do that, monitoring the voltage so that I unplug when we get to 15 volts. I may also leave the caps off the wet cells so that I can watch the bubbles -- very entertaining.
Naturally, all of this info has prompted another question -- how often to top charge? I enjoy periodic maintenance on camping gear -- somehow, the same is not true when it comes to my stick house . . . .
