12 v inverters and lighting

[Shu]

I just salvaged 2 back up power supplies. The batteries are dead and that is of no concern. What I was thinking is I just got 2 really cheap battery chargers. Now I think I have even more becuase there is an inverter circut that takes 120 v ac converts it 12vdc and 12vdc to 120 v ac. With some sorting of the circuts I should be able to power a couple of 12v lights for the reloading bench or maybe walkway lights etc. I am no electtrical genius but can run a multi meter and splice a wire or 2. Has anybody done this sort of thing to power lights, a fan etc?
Oh and I can still charge 12 v batteries.

[RemingtonMagnum]

Hi Friends
Not knowing how your charger is made and set up I would say evens that you will burn up the entire unit. Not all circuits will work are function properly in both directions. Just be safe buy a cheep system from the Solar panel store. Some come with simple diagrams and some are as simple as connecting battery clips and insert the 120 V house plug.
 
Do I smell something frying?
 
Don Jackson Remington Magnum/Ultramag

[Lloyd Smale]

why would you want 12v lights when you have 120 avaialble?

[Shu]

The thought behind 12v lighting is energy savings. The BPS can charge 12v batteries but they wont run something big for very long. A 12v deep cycle battery can run a ceiling fan and a couple of small lights for several hours. Picture a remote setting or possibly needing emergency lighting.
 
Maybe a small hunting cabin where you don't want to run a generator for very long. Charge the batteries then let them run your 12v appliances. You could charge your i pod, cell phone, emergency radio etc from this also.

[efremtags]

your setup should work fine. I would confirm that the battery charger can properly charge a 12V deep cycle battery you will buy. I would buy the same class of battery that the original unit had, to insure they charge correctly. You don't want to mix flooded an sealed batteris and vice versa because the charger will not properly charge the battery.

[Shu]

Thanks!!
I thought I posted in the wrong forum for a bit.

[vacek]

I guess I am a little confused as well.  However, if you are wanting to be able to charge some deep cell remotely then solar is a good option as is a vehicle.  There is an article in the Backwoodsmen a couple of years ago that deals with this in detail.
 
If you are talking about pre-charging your deep cells via 120 AC then re-converting it back to 120 via an inverter, you can but unless you are charging then hauling batteries to a remote location, I don't get it.

[efremtags]

adequate solar is xpensive, if you re just running some small accesories for  day or 2, the proposed method would work fine. A typical 100AH battery will deliver 960watt-hrs, so that's a 100W bulb for 9hrs+. Thats plenty for low wattage lighing for a night or 2. If you have a small genset already, you can charge bateries durign the day, shut it down at night and keep your lights, etc intact quietly.

[Shu]

The plan was to make generator fuel last longer. Say I went to my cabin for 2 weeks. I would only have to take 5 gallons of fuel for the jenny. I haven't bought the cheap panels and that would be an upgrade. My plan would be to run the generator an hour or so just to keep the battery topped up. Use the 12v lights at night.
I should probably just by the cheap harbor freight 3 panel set up and forget experimenting but were is the fun in that.
I agree switching from 120 to 12 back to 120 would not be a brilliant idea.

[Lloyd Smale]

thats where i was confused. It would never make sense to use 120 vt stepped down to 12v for lighting. You loose to much just in the inefficentcy of the inverter. Even at our camp we only use the invertor to power things that cant be powered by 12vt solar panels. Things like the colared tv, vaccuum cleaner ect. Just running an invertor will suck down a battery even without a load. Keep in mind that if you want to run a 25 watt bulb at 12vts it takes 2amps of draw. run that same 25 watt light bulb with 120 vts and it takes about a 1/5 of an amp. Higher voltage will allways be more efficient then lower voltage. I dont know how big your camp is but another problem with low voltage is line loss. If you hook a #14 wire to a batter that is 12vt and measure the vt 25 feet away you will see what i mean. then you have to figure in the high amperage loads you will be using with that low of voltage..  Anytime you wire something for low voltage you have to use the biggest wire you can afford. I wouldnt wire anything for 12vt with less then #10 wire and even that would be only for short runs. .

[Gaz-52]

 Hi Shu.
           I hear what you are saying about charging the batteries when the generator is running ,then using battery power to run the lights when the noisy generator is shut down at night ( the silence is great,yes?).
         You might like to try some of the new LED 12volt lights that are around now. They are very energy efficient & don't need really heavy wiring like conventional 12volt  lights. But you should keep in mind that  the route length of the cabling should be kept as short as possible to reduce "voltage drop" in the system.
         The simpler the system ,the better I believe .  The inverters are great for powering gear that can only use A C 110 or 240 volts like power tools etc. JMHO.
              Cheers Gaz.     

[Shu]

Thanks!!
Running the jenny in the evening just kind of kills the peace of it.

[Lloyd Smale]

we have 4 solar panels at camp. We run them into two larger deep cycle batterys. When its sunny outside and were outside or hunting they will charge enough to run the small 15 inch tv and a couple lights at night. If it overcast or someone is in camp during the day using the tv we will need to run the generator abd battery charger for a couple hours a day to keep up. Its pretty close since we added the second two pannels and id guess if we bucked up and bought two more we wouldnt need the generator at all for 12vt load.

[efremtags]

The only issue I see with 12V accessories, is you can't run it off the genset directly, so if you have battery issues, you are SOL. Besides, 12V accessories requrie 10x+ the wiring ampacity that 120V do. 1A at 120V is 10A at, not accounting for voltage drop, which drives it up further. A #10 wire can handle 30A of 120V current, but only 10-12A of 12V current, otherwise voltage drop is excessive. Have you priced copper these days!


The simple solution is to use the genset with your existing accessories, and use the battery/inverter as a nighttime convenience, since you have the charger for free and inverter already. I would invest in compact fluorescent lights. Screw LED ligths, they cost 50x as much, and may requrire new receptacles to work properly. We are 3-4 years out from having cost effective LED lights.

If you were doing a real offgrid home, I would utilize AC for everything for the reasons stated above, and invest in a high effieiency inverter with a battery charger built in at 48V. I have built large systems like this for powering state park facilities and remote cell towers.