If you're only out boondocking for three days tops, skip the solar altogether and use that money to expand your battery bank even if that means moving them to another location altogether. The DW and I boondock for 4 days tops and only use our batteries. We average 4 hours a day of sat TV and Bluray movie watching, however much furnace we need, unlimited lighting (all LED's). I don't even turn off the inverter. Our biggest limitation is water capacity. We have yet to get below 85% SOC. We have four big L16 6V's @ 740 amp hours total (370Ah each). Click the link in my sig for more. The L16's go all the way to 435 Ah.
You are only using about 39 amp-hours per day. Westend has a fridge that is going to do about 80 amp-hours by itself. If we add your 39 amp-hours to that total he needs 119 x 6 = 714 amp-hours. As the battery voltage drops the inverter will become hungrier for amps. I seriously doubt he can do 3 full days. Three days and two nights yes.
Maybe instead of worrying about replacing the power the AC fridge uses while doing a 3 day at the creek, you could unplug it and use a cooler with a block of ice. You could use a lot less solar and get by.
westend wrote: John, I have the fridge plugged into an AC outlet in the shop, no inverter present. I have a smaller inverter around here is you think it would be moe relevant but I won't be using that one in the TT.
I see. You threw me off with the measuring the DC comment.
I don't believe you should use a small inverter because a small one may not have the higher surge Amps needed to start the compressor. Do you know the starting Amps of the fridge?
There are a few people around who have field experience using a residential fridge.
I would still like to know the numbers for Watts and VA while the fridge is running. Also the PF.
The Kill-a-watt syas 80w, PF of 1.0 and the VA starts at 130 (besides the compressor initial bust) and quickly descends to below 120 va.. The starting amps is somewhere around 1.5-2.0 amps. I was looking at the Gopower and Samlex inverters up to 600 w..
I'm starting to see, now that I have some usage numbers to work with that the small fridge is the pig in yard, so to speak. I have no problem using a cooler with a couple of blocks of ice and that may be the best resort for boondocking. The fridge could be used when I'm on the pedestal power. Same thing for the microwave and the coffee pot. I can always make coffee with the propane stove.
If I start to eleiminate some items then the battery bank can be sized to less than the required amp hours and a panel or two should fit my needs and budget. Someone earlier mentioned marine 12v refidgerators and that's something I could also look into, we have a pretty high boat/capita around here and something used might be available in that regard. I hadn't thought about 12v refidgeration. If I altogether eliminated the power-sucking fridge, what size of battery bank should I be aiming at?
I don't know what this "dorm fridge" could be, but I would rather take it back to the big box store it came from. Stated 1.8 cu.ft size I wouldn't even call a dorm fridge - it's more like a very small (THE smallest) DC compressor fridge that TC people install in the cut-out of the previous LP fridge. But those draw 240-260 watt-hours a day - 5 times less than what the OP has got.
3 days scenario with a standard LP fridge? Let's see...
15-20 AH for parasitic loads including fridge, plus 20-30 AH for his enjoyment - LED lights, few hours of either laptop or small TV. Plus, few AH inverter losses on either charging a laptop or running a TV. 40-55 AH total, more or less. With 200 AH battery he'll be fine, it will stretch TAD due to very low currents. May be will come home at 30% SOC once in a while. Throw in small 80W solar for a piece of mind. Should be alright without small solar either.
The beauty of solar (even 80W) is that it will let you stay much longer if you have to, due to some unexpected problems, though with a minimal comfort. It will cover your 20AH parasitic losses and fridge, and will prevent battery from dying, for many-many days, though you will have to go to sleep when sun goes down - no lights or TV.
Or - what Mena said - increase the bank further. Say, up to 300 AH. Extra 100 AH will cost same or less than 80W solar and controller.
Almot wrote: I don't know what this "dorm fridge" could be, but I would rather take it back to the big box store it came from. Stated 1.8 cu.ft size I wouldn't even call a dorm fridge - it's more like a very small (THE smallest) DC compressor fridge that TC people install in the cut-out of the previous LP fridge. But those draw 240-260 watt-hours a day - 5 times less than what the OP has got.
3 days scenario with a standard LP fridge? Let's see...
15-20 AH for parasitic loads including fridge, plus 20-30 AH for his enjoyment - LED lights, few hours of either laptop or small TV. Plus, few AH inverter losses on either charging a laptop or running a TV. 40-55 AH total, more or less. With 200 AH battery he'll be fine, it will stretch TAD due to very low currents. May be will come home at 30% SOC once in a while. Throw in small 80W solar for a piece of mind. Should be alright without small solar either.
The beauty of solar (even 80W) is that it will let you stay much longer if you have to, due to some unexpected problems, though with a minimal comfort. It will cover your 20AH parasitic losses and fridge, and will prevent battery from dying, for many-many days, though you will have to go to sleep when sun goes down - no lights or TV.
Or - what Mena said - increase the bank further. Say, up to 300 AH. Extra 100 AH will cost same or less than 80W solar and controller.
I'm not quite following a few things here, what is "TC people"? I do understand your feelings about the fridge. I have no parasitic loads, basically. If I use an inverter I guess that would be considered parasitic but my alarms are battery powered at the devices. I don't think I could buy and install even an 80w solar system for the price of a 100AH battery. As I mentioned previously, I have 100 AH in the house, at present and have room for two series 31 batteries on the toungue. With a little work on the battery enclosure, I could hook up two 6v GC batteries. I am definitely going to increase the size of my battery bank, it is just a matter of trying to estimate how much I need to add.
Thanks, Don, for the translation and thanks for staying with me on this. The little fridge may not be quite the boar I thought it was, the overnight consumption figures shows a marked decrease. The rates, now, depict a 24 hr. use of .62 KWH, still an energy hog in the terms of 12v. but the numbers will probably slide further as the fridge breaks in and it isn't operating in 90 f ambient.
I liked your baseline of taking the solar into two categories, battery charging or full energy supplying. I think I've already figured out that enough solar to get comfortably into the latter is not going to be in the cards and it probably shouldn't for a 40 yr. old TT. The rub is that if I purchase two 31 series or two GC batteries, my AH bank is going to be around 300 AH and that might move me close to category two with the solar. If I bought 2 x DMsolar 140w panels and a simple PMW Morningstar charger, do you think I would meet any kind of sweet spot for recharging and using the 300 AH bank?
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