Interesting. I can’t really figure this out. Charged all night then turned off the battery power switch and tested voltage,13.49v. BMV reads 99% so I think I have some mistake in the settings. So I unplug and start engine to use DC to DC charger hoping I can get 100% and re-synchronize. I check voltage and it is of course reading 14.34. 14.4 is set as 100%. I turn off the engine and disconnect batteries and get a 14.35 reading on the multimeter. So I re-set the BMV to 100%. The outcome I expect is that further charging from the PD will still be necessary. So now with the engine off but the charger running the isolated batteries read 14.5 instead of 13.49. Charging now at the higher rate but while disconnected?
But when I disconnect the batteries and unplug the RV I’m getting 14.04. I don’t understand how that little time on the DC charger could up the voltage by that much. And when I turn the battery switch back on without charging the voltage drips precipitously. I’m thinking it might stabilize at the original 13.49v but although it slows down it still shows about 3 min of time left for each minute that passes!
And I guess the SOC does not reflect this change. Maybe because it needs 10 min averaging. But I still think I’ve made a logic error in the settings.
I switched from 200ah to 210ah. Full charge voltage is reset to 14.5. So if the battery is depleted at 11.5 volts I have 3 volts of battery power. 13.5 is about a third depleted. So I reset the SOC manually to 65%.
After about 30 min of battery use I’m showing 13.27v. 64% SOC and an astounding 1 day left of battery power! Under the same load that gave me only 7 hours last I checked.
So what happens if I plug the PD charger back in?
It starts sending a good amount of charge into the batteries. Hopefully up to 14.4 or 5.
This is still under the fan load. And I would expect exactly this behavior. Charge going in SOC increasing. But I’m not seeing the opposite except when I left the application for 30 min. SOC stays at 100% even thought I’m using battery power at what is being calculated at a quick pace.
Original problem was BMV read 100% at ~13.5 volts. Reset SOC to higher voltage using DC to DC charger following advice here. Charged only briefly voltage multimeter reading increased about half a volt. Running load for about 15 min decreased voltage quickly. Verified with multimeter. No decrease in SOC.
Reset parameters in application. I had 90% depletion floor but I changed that to 20%. Thinking it meant percentage left not percentage used. Retested and it appears SOC is responding to actual depletion. Just checked again and SOC is 100%.
But not showing the fan load! Reset the battery switch and now it’s showing the ongoing load and a drop to 14.1v. And again dropping fast. This is so weird.
So something is wrong here or this BMV takes a long time to get set correctly. What am I missing? Is it time to call Victron?
