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Small Cabin Forum / Off-Grid Living / Need some help with powering up my cabin
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ritz cracker
Member
# Posted: 9 Aug 2014 09:08pm
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So long story short I built a 12x30 cabin. Wired it to a 100amp breaker box. There's 6 led lights that. Draw 10amps each.i will have a 46"flat screen tv and a 32" flat screen. With two DVD players. I only use it on the weekends Friday to Sunday. Right now I use a 3500 watt generator to power everything(it's a no name).works great but at night I would like to not have to hear the generator running. So I was wondering if I can get a batterie bank setup to use at night. I know others are using them. My question is how do I connect the 12volt to my breaker box. Is there a inverter that I can hard wire to the top of it? If so the name would be great. My other question is can I charge the batteries with my generator. Or do I just use a regular car batterie charger. Thanks for any help

bldginsp
Member
# Posted: 9 Aug 2014 09:34pm
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You'll need a charge controller for the batteries, an adequate number of amp-hours in the batteries, and an adequately sized inverter. But that's doing it in reverse. First figure out your total loads in watts, from that figure enough batteries to supply that load for the length of time without depleting the batteries more than 30%, get an inverter large enough to handle the load but not much larger, and then look at charge controllers to charge the batteries. Since you are charging with a generator you want to charge as fast as possible to minimize gas use, rather than a trickle charge. I don't know how fast batteries can be charged.

Your LED lights are probably 10 watts each, not 10 amps.

That's a start

MtnDon
Member
# Posted: 9 Aug 2014 09:44pm - Edited by: MtnDon
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That's a lot of TV for a 20x30.

Quoting: ritz cracker
My question is how do I connect the 12volt to my breaker box.


You don't connect the 12 VDC directly. You use an inverter to make 120 VAC from 12 VDC.

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Quoting: ritz cracker
Is there a inverter that I can hard wire to the top of it? If so the name would be great.


There are many inverters to choose from. Naming names will more or less just indicate what the responder owns.

With the low power loads you only need a small inverter (200 to 400 watts depending on what the TV's and DVD's draw) unless your uses grow. Small inverters like that are not hardwired types; normally these have outlets built in. You could use a cord and plug from the service panel, depending on if there are inspections or not. Hardwire usually starts at over a couple thousand watts. Better hardwire inverters include battery charging capabilities.

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Quoting: ritz cracker
batterie bank setup to use at night


Most likely you can get away with a pair of 6 volt golf cart batteries, based on the low loads mentioned. That would probably let you run the generator only once over the weekend. Be aware that if the use (and recharging) is sporadic, with a month or more between visits, the batteries will be self discharging and that will have harmful long term effects. A small solar panel can keep the batteries charged for months on end, though probably not having sufficient output to recharge a discharged battery.

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Quoting: ritz cracker
can I charge the batteries with my generator


Use a battery charger powered by the generator. The best will NOT be ordinary car chargers but like an Iota and sized to suit the battery capacity.

Note: A battery charger is powered by AC (usually 120 VAC) input power to charge batteries whereas a charge controller is used to take DC power from PV panels and wind or hydro generators to charge batteries.

ritz cracker
Member
# Posted: 9 Aug 2014 10:02pm
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Yes the lights are 10 watts each, sorry.im looking at the renogy solar panel. The 300 watt kit, with the 30 amp charge controller.its about $500 without the inverter or the batteries that I would need. So I figured I would start with the batteries and the inverter. Since I have the Generator to charge them.Then when I have the extra cash get the solar panels. It is a lot of TV. Lol I have a 12x12 loft for the kids and then living space (for me)lol. Now when you say use a cord to plug in the inverter then cut end and hard wire it to the breaker box? If I get the buggier inverter that can be hard wired in to my breaker box do I just tie it in to feed on top of breaker box.main two lugs? I'm a plumber not electrician lol

bldginsp
Member
# Posted: 9 Aug 2014 10:22pm
Reply 


The inverter will have lugs to send out the 110/220 AC power, the two hots, neutral and a ground. The wires between the inverter and subpanel should be sized to handle the maximum amperage that the inverter can produce.

Here's what I don't know about inverters supplying a panel board- does the inverter bond ground and neutral or do you do that at the panel?

MtnDon
Member
# Posted: 9 Aug 2014 10:34pm - Edited by: MtnDon
Reply 


Quoting: ritz cracker
If I get the buggier inverter that can be hard wired in to my breaker box do I just tie it in to feed on top of breaker box.main two lugs?


Service panels vary. Some may be designed to operate with only 120 VAC, others use a 240 VAC feed. If yours has a single hot and a single neutral incoming connection point then yes, a cord can have one end hardwired to the inputs and the plug on the other end used to plug into an inverter or even a generator. So you could use one or the other to power the cabin. But the two should never be connected to power the cabin at the same time. You'll lose the magic smoke in one or the other; perhaps both.

The battery charger could be plugged into the generator outputs and connected to charge the batteries as a totally separate thing.


IMO, it does not pay to get a large inverter, one much larger than the power needs, just to have hardwire ability. A big inverter run for a low demand is not very efficient electrically. Not to mention the wallet/checkbook.


Before spending any money be certain to know what the power needs will be. If you have been using the cabin with generator power only for a while you will have a better idea than if this is all just theory right now. Total up the watts of everything that is used at the same time. Add 20% for safety; that is the size of the required inverter.

Adding and multiplying the watts and the hours used will help you work towards the battery capacity needed. When you have the watt hours used in an average day or weekend come back and post that info. There are many folks here who can help to estimate the needed battery capacity.

When the battery capacity is known then the size of the battery charger and/or PV panels and charge controller can be determined. Everything begins with the amount of power to be used in a daily period, as bldginsp mentioned.

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