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Small Cabin Forum / Off-Grid Living / Taking power with
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# Posted: 12 Feb 2020 03:09
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Hello my friends.
I have 2 12v marine master batteries and a 500 watt inverter. Right now all i have at the property is generator power from an old rv. Its expensive to run so im hoping to charge these batteries and take them with.

About how long will 2 12v deep cycle batteries last running a laptop a blue tooth speaker and cell phone charger?

The calculators online give me a head ache. Just looking for a ballpark figure.
15814949659712537357.jpg
15814949659712537357.jpg


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# Posted: 12 Feb 2020 03:11
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With it being winter between the kids and me the laptop will be running 12 to 14 hours a day.

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# Posted: 12 Feb 2020 03:18
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A better list
One lamp with led bulb 9 watts i think. 8 hours per day
One laptop. 40 watts 14 hours per day
One speaker bluetooth watts? Maybe 8 watts?8 hours per day
2 cell phone chargers maybe 6 watts 8 hours per day

qbodsyt
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# Posted: 12 Feb 2020 07:01
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Based off of your battery pic it seems like its rated 23 amps x 2.5 hours, so 57.5 amp hours? Two would make for 115AH then. Your usage looks to be just under 800 watts a day, so that would be 66AH (WH ÷ V) I'm not sure your cell phone chargers need to be going nonstop 8 hours a day but that's your call.

You'll have power loss due to efficiency from your inverter too. And you won't want to run your batteries past 50% depth of discharge.....so I'm guessing the two batteries being used responsibly for long term life would be useful for less than a day?

A lot of other people know more about this than me, my calculations might be wrong, but if your batteries are rated for less than 60AH each I don't think two of them are going to be enough for your usage.

Brettny
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# Posted: 12 Feb 2020 07:27
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Those battery have a CCA rating. There not real deep cycle battery and will not even like 70* discharge. If you must use them you should really get some kind of charge on them while at the cabin. Solar or a small generator.

Jet.com has these very portable and light 1000w inverter generators for $200. There very quiet and I'm getting 8-9hrs on 0.5gal of fuel. There so quiet that at the end of a 50ft cord you almost can't hear them.

https://jet.com/product/Sportsman-1000-Watt-Inverter-Generator-CARB-Approved/63106407 be76422095c9a5de6e45fa90?beaconId=4c1d963f-c81f-471c-aeac-e31a317506ce%3A17&experienc eId=21

Aklogcabin
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# Posted: 12 Feb 2020 11:08 - Edited by: Aklogcabin
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I don’t know if this help but maybe something to work off of. I have a 12v truck battery. Maybe 650 to 800 cold cranking amps cant remember exactly. I could recharge my laptop, batteries for the screw gun, led lights when dark, in the winter. That Kind of ever day stuff. Battery is now 3 or 4 years old. Would probably need recharge in 3-4 days from generator for a couple hours. So I just have a small charger and when I’m needing a power saw or just plug in the hot pad for my back turn a light on to cook dinner the charger goes on the battery. It worked itself into our schedule as needed.
And all thats needed is a small generator 2-3 k or so which are pretty quiet and economical. My generator is in a generator shed so that also minimizes sound.
Good luck man!

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# Posted: 12 Feb 2020 21:43
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Ok so maybe a day with batteries. Could i then use the generator to charge the batteries for what like a couple hours?
Then Im still saving by not using the generator much of the day and all night.


For the phone chargers i was thinking 8 hours because i normally plug it in before bed then sleep 6 to 8 hours.

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