Battery chargers, inverters, engine generators-parameters

[booster]

Originally Posted by markopolo

I've suspected that some solar installs could trick the charger into quitting charging too early. An automatic solution would be using something similar to an automatic transfer switch that shuts off the solar panel output when it senses that you are plugged into grid power.

I think your suspicions are proving out to be correct, and I would bet that most solar systems are messing with other things. Folks like Handybob, who are nearly completely solar wouldn't see the issue as much as someone who has solar and uses shore power semi-regularly. Of the limited number of chargers I have personally seen, I would say the Tripplite and Xantrex would not go into absorption mode and go right to, and stay in, float. The Ctek would run a complete cycle as it always goes into all the steps, based on timers, it appears, but they are tiny and not suited for what we need. The Blue Sea would run a full cycle through absorption, but would not stay in aborption as long as it should because the solar would mess up the ending amps and take it to float. I am glad that I added an on/off switch to the solar so I can turn it off when we go on shore power, and as you say, it could be automated pretty easily with a relay that turned off the solar when on shore power or generator (110 volt coil relay). By the same issue, if the shore charger is on when the sun comes up, it seems to be able to put the solar into float for the whole day, so it is a two way issue.

I haven't really understood, and still don't, the charge profile that it appears that Progressive Dynamics uses. I think it is always 4 hours at 14.4 volts, and then to 13.9 volts, and then after more time to 13.2 volts or so. The 14.4 volts would be a combined bulk and absorption, I think, but PD says that takes the battery to something like 90% and then the 13.9 volts finishes it off. This is very different from all the other profiles, and what folks like Trojan recommend (even recommending a very high ending voltage). One thing that the profile they do would work well for is the above mentioned solar applications. From what it looks like, the charger would run the same profile no matter if the solar was holding up voltage and generating amps, or not. In this case, the very simple could very well outperform the quite complex chargers. You could duplicate that type of profile with the Blue Sea by zeroing the ending amps and running on the absorption min and max timers, but that would defeat many of the benefits of charge control from ending amps.

I think we may start to see solar setups, and/or chargers, that take crosstalk into effect in the future, as I think there are going to be many disappointed folks who put solar on and don't get the results they expected.