Trailer: Bigfoot 3000 & Barth "slide-in" truck camper
I have something interesting to report.
We had several days of overcast, with a deluge in the middle spanning two night and the entire day in between, and closed out with half a day of fog today. For the first time my panels were not able to recover to a full charge the next day, or even the day after. Tomorrow should see me topped off again.
Aside from making sure things were turned off when I was away from the camper, I used my normal loads, and perhaps a bit more as I was stuck inside some of the time and I wanted to exercise the system some. The rain was so loud I did not sleep well. I used my electric blanket every night, as I have since I first got it, first on high (10) to warm up my bed and then dialed back to 3 or 1 overnight--which account for between 20 and 40 AH. I recharged my laptop, watched TV, and ran my other normal loads.
What I take away from this is my panels can recharge my batteries rapidly when I am more deeply discharged, but in this case they can't do the final top off charge because that takes a few hours at lower charging currents and I run out of daylight. I could handle another day or two of very dark overcast conditions or heavy rain and expect a pretty rapid recovery once the sun comes out, and still be above 50% capacity. I estimate I can recover 180AH, or perhaps much more, of discharge if I was discharged to greater than 200AH. So if I don't care about recharging the last 15-20%, which takes longer, I can cycle a bigger daily load if needed without any problems, as long as I fully recharge it periodically.
I have been slack at recording data, so the data is a bit sparse compared to previous weeks.
Being able to simply switch off all DC loads except the refrigerator with one switch, and the Inverter with another is all I really need to do. Knowing the charging currents is nice though as I sometimes throw the surplus electricity into running my refrigerator though the inverter.
The AH capacity of the bank is 400 AH, so when above 100AH, the percentage should have been below 75%, which it was not. It is a very small error, and has to do with the battery monitor synchronization. Taking it up to a full charge using a shore power connection for several days would fix that.
Note that in heavy overcast and rain, I was still pulling 2-3 amps charging current out of 630 watts of panels which represents 6% of the maximum amount for horizontal mounting. This is for three sets of two panels in series. Equivalent to three 210 watt 36 volt panels in parallel. In any event it is an interesting percentage which can be used to estimate charging for panels mounted in a 36 Volt configuration.
Here is what I recorded:
Battery %, Amp Hours used, Charge or (-) Discharge rate, F-furnace, I-inverter, Battery Voltage, Battery temperature (F), Ambient temperature (F-A), C-Cummulative AH's recovered.
Apr 29: cold overcast
0217: 92.6%, -31.1AH,-7.8A. F & I on , 12.54V, 79F , 47F-A1112: 87.2%, -52.2AH, 2A, 12.68V, 75F , 47F-A , (w/F&I off 5A)
Left DC off but inverter on idle
2345: 89,8%, -42.4AH, -5.3A F on, 12.48 V , 70 F , 42.1F-A
Apr 30: rain, dark
1302: 75.3%, -101.2AH, 0.0A,12.34V, 70.5F, 43F-A, everything off 2.1A
May 1: fog, clearing in early afternoon, becoming sunny and clear
0109: -93.2 AH, furn on, -3.2A, -6.8A w/inverter on
1059: 67.4%, -133.4 AH, 7.1A, 12.30V, 74F,
2003: 94%, -22.0 AH, -0.6A, 12.92V, 88F, 63F-A, C111.4AH.
I recovered 111.4 AH today. I am happy with that.