Let's talk float voltage.......

[boywonder]

I’ve somewhat recently upgraded to a Victron smart solar controller which allows very easy changing of the battery charging parameters and now I’m addicted to changing the float voltage while camping.


With my old setup (and with the new one as well if I leave the float voltage alone) when arriving at camp fully charged and then running some heavy loads like the electric water heater, microwave, etc it’s a little annoying that I’m parked in the sun but since the house battery is nearly topped up the controller isn’t sending much energy/power to the battery until the battery voltage drops below the float voltage to get into bulk charge mode.

I can be camping for a good part of the first day (well ….any day really if the battery is charged) without putting much energy back into the battery if the battery stays above the float voltage.

If I crank the float voltage up to say 14V or so while camping every time the water heater cycles the watts/amps from the solar panel go way up providing all of the current needed for the water heater and preserving the battery state of charge, since the voltage will drop below 14V and get the controller back into bulk mode. If there is plenty of sun I can end the day with the battery still around 95-96% state-of charge. This is vastly different than my old setup where by day three my old AGMs were getting down around 65% SOC or lower.

I understand that my Lithium battery far outperforms the AGMs but in hindsight if I could have easily increased the float voltage on my old controller while camping I could have played this same game.

When I get back home and the van sits in the driveway I set the float voltage back to 13.4V since there is no load on the battery and Lithiums are happy being around 50% SOC when not being used.

I’m curious if other people have tried this and what people’s thoughts are. I think Andy/”Off grid garage” played with this on his youtube channel; that’s where I got the idea.