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Old 02-01-2018, 08:04 PM   #1
Mini-Skoolie
 
Join Date: Dec 2017
Location: Duncan, South Carolina
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Electrical setup/Inverter Question

Hello Everyone! We got some great help on our last post and hoping for the same, you guys are great! So getting into it we plan on having AC and DC.

AC-fridge(converted chest freezer), blender/rice cooker/crockpot, laptop, and a triple light fixture in kitchen(maybe)
DC-led lights, ceiling fans, cameras, gps, water pump, inverter?

The plan for the setup is 400-800watts of solar going to a charge controller then to about 600AH of battery. A DC fuse strip will come off the batteries and that will take care of the DC side of things. Now for AC I'm not sure the best way to go about it. I believe I could put a 2000w standby inverter off of the battery and a breaker panel off of that to power AC, but I really don't want a large inverter running 24/7 just for the fridge... is the only other option 2 smaller inverters that way i could turn one off when not using kitchen appliances or laptop? but then one will still have to run 24/7? Any other options I'm missing?

I just feel like without that fridge and inverter running all the time we could be off grid for so much longer. We will have a genny to help avoid rv parks and extend adventures just want to set up our system so that we can ration our electricity when we need to. Cant wait to hear from you guys! All suggestions greatly appriciated!
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Old 02-01-2018, 11:47 PM   #2
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The fridge is definitely the biggest total power draw though the rice cooker and crock pot will draw more but for a short time. LED lights and cell phone chargers only draw a watt or two and my laptop charger draws 10-15 watts.

Your best bet is to figure your power needs then design your solar & battery capacity to match. Remember that the inverter will draw 10 to 15% of your battery power in the conversion from DC to AC. A Kill-a-watt meter can give you a good idea what your appliances are actually drawing.

Remember that a 12v amp is less energy than a 120v amp. To keep it simple I convert amps to watts.

Watts = amps*volts
Amps = watts/volts
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Old 02-02-2018, 06:58 AM   #3
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Quote:
Originally Posted by mapletwag View Post
... but I really don't want a large inverter running 24/7 just for the fridge... is the only other option 2 smaller inverters that way i could turn one off when not using kitchen appliances or laptop? but then one will still have to run 24/7? Any other options I'm missing?
It is a good question and afraid I don't know the answer. I have wondered the same thing as I have a residential refrigerator. I think the answer depends on the inverter (make/model). In the not too distant past, inverters consumed a good bit of power in standby mode and there was even a rule of thumb (x percentage of rated output but I can't remember what X was). I've heard that new/modern inverters are more efficient in standby but again, I don't have details.

I can tell you that, according to the spec sheet (I've not actually measured it), my 3000 watt, 24 volt, PSW inverter consumes about 1.5 amps (@ 24 volts - or 3 amps @ 12 volts) in standby mode. I've seen a few smaller inverters (400 watt-ish) that state they consume 1 amp @ 12 volts in standby mode. So there does seem to be a savings though it isn't linear.

Either way, it is a good bit of power over the course of a day so I think the idea has merit.
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Old 02-02-2018, 10:18 AM   #4
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Quote:
Originally Posted by roach711 View Post
The fridge is definitely the biggest total power draw though the rice cooker and crock pot will draw more but for a short time. LED lights and cell phone chargers only draw a watt or two and my laptop charger draws 10-15 watts.

Your best bet is to figure your power needs then design your solar & battery capacity to match. Remember that the inverter will draw 10 to 15% of your battery power in the conversion from DC to AC. A Kill-a-watt meter can give you a good idea what your appliances are actually drawing.

Remember that a 12v amp is less energy than a 120v amp. To keep it simple I convert amps to watts.

Watts = amps*volts
Amps = watts/volts
Great info!!

Power consumption of devices can vary though. Check the particular devices that you are going to be using. My laptop draws closer to 60 watts and my cellphone up to 5 watts.
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Old 02-18-2018, 07:01 PM   #5
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Join Date: Feb 2018
Location: Fort Collins, CO
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Quote:
Originally Posted by mapletwag View Post
Hello Everyone! We got some great help on our last post and hoping for the same, you guys are great! So getting into it we plan on having AC and DC.

AC-fridge(converted chest freezer), blender/rice cooker/crockpot, laptop, and a triple light fixture in kitchen(maybe)
DC-led lights, ceiling fans, cameras, gps, water pump, inverter?

The plan for the setup is 400-800watts of solar going to a charge controller then to about 600AH of battery. A DC fuse strip will come off the batteries and that will take care of the DC side of things. Now for AC I'm not sure the best way to go about it. I believe I could put a 2000w standby inverter off of the battery and a breaker panel off of that to power AC, but I really don't want a large inverter running 24/7 just for the fridge... is the only other option 2 smaller inverters that way i could turn one off when not using kitchen appliances or laptop? but then one will still have to run 24/7? Any other options I'm missing?

I just feel like without that fridge and inverter running all the time we could be off grid for so much longer. We will have a genny to help avoid rv parks and extend adventures just want to set up our system so that we can ration our electricity when we need to. Cant wait to hear from you guys! All suggestions greatly appriciated!
If you haven't bought your appliances already, there are 12v fridges available. That could let you get away with a much smaller inverter, and you wouldn't need to run it 24/7.
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