Cold weather / High Voltage

couchsachraga

I ran in to something new-to-me over the weekend, though I suspect it is only because my monitoring equipment is better than in the past (and charge controller...).

My off grid system has always gotten cold (below zero F cold) at times, though I'm working on a solution to keep things (hopefully) 40F and above going forward.

I followed my normal routine when I got there - open propane valves, fire up the heater, check solar system / batteries (fully charged), and turn on the SureSine inverter... which for the first time ever gave me a fault code (two red lights). Thankfully I keep the manual up there, and quickly determined that one possibility was higher than 15.5V. So, I switched my trimetric over to V and sure enough, 15.6V coming off the Midnite Classic 200 (not in equalize, was set for the proper voltage for the T1275's. Was around, but not at 14.3 - I don't have it written down here). But, the Midnite has temperature correction, and looking at a few tables sure enough at the temp in the place (teens) that IS what I'd expect it to be given a temp correction.

Any thing to worry about / any other "corrections" it would be wise to make, other than the very obvious keeping the place warmer that I'm already working on?

Thank you all as always!

Cariboocoot

Re: Cold weather / High Voltage

That's normal to be sure. Cold batteries need more V to do their thing.
The down side is (particularly on 12 Volt systems) that higher Absorb Voltage can exceed input max for inverters and other (DC) equipment.

Also your SG will read incorrectly at low temperatures so don't trust any initial reading. After charging it should be warm enough to be correct (temp correcting hydrometer or scale is nice).

westbranch

Re: Cold weather / High Voltage

you didn't say which stage of charge your CC was in, other than it was not in EQ.

depending on which stage, and outside conditions, you could add a 12 v load to drop the V or turn off the PV input if you needed the 120v power.

couchsachraga

Re: Cold weather / High Voltage

Westbranch - excellent suggestion, and exactly what we did... just not in the right order. First i turned everything on I could, short of the biggest load, which is my water pump (I could have primed it easily, but didn't want to risk any freezing in the diaphragm pump ripping. I drain it, but with condensation and such I'm sure that could have happened). THEN I remembered (and realized) it was still up that high as the solar panels were putting out plenty of w even on the cloudy day (batteries were at 100% remember... by Trimetric and MC 200 anyway), so I disconnected the charging (glad I finally put THAT switch in) and sure enough the voltage dropped immediately to 14.1 or so.

westbranch

Re: Cold weather / High Voltage

Once you got the inverter going did the CC kick back up to > 15.5 or ? and shutdown or was the running load enough to keep the V down?

couchsachraga

Re: Cold weather / High Voltage

Running load, and warmer temps, were enough to keep the voltage down thankfully. The load was the AC fan for the heater (I tried to find a replacement DC one but couldn't), though we added in an additional light (standard florescent) and that helped a lot too.