running TV off car battery - off grid

[cbc58]

I had the chance to stay in an off-grid airbnb tree house rental and the guy had set up a digital TV to run off a car/marine battery.  If one were to do that, is there a low-cost solution to have the car battery get recharged using a small solar panel so you don't have to haul it back and forth to an electricity source?  I saw something like this in a small boat used for an electric start motor...  A quick google search shows some battery solar options but perhaps someone can suggest the best make/model solution.  Tks

[MountainDon]

Start with how much energy the TV system is consuming.  Both while running and while sitting idle. Once you know how much is being consumed you can then figure out how much solar would be needed to replace that power with the average available sun.  If the TV operates on AC the inverter losses would have to be considered as well. Some inverters are much better (lower self consumption) than others.

[ChugiakTinkerer]

One solution is a small generator and 12V charger.  Otherwise you'll need to follow MountainDon's advice and do some figgerin' so that you can have a solar system that matches your needs.

I use a CPAP machine when I'm at the cabin or out camping.  My power solution is a 17 amp-hour 12V sealed lead acid battery, which I can recharge with a generator or with my solar panels.  Panels are portable, a pair of 20 watt Instapark panels connected in parallel to a Sunforce 10 amp charge controller.  You want a charge controller so that it doesn't overcharge the battery and also doesn't drain it when the panels aren't illuminated.

[cbc58]

tks for the replies.  doing a little research there are TV's made for RV's that run on 12V DC -- so I guess it is a matching process for the particular TV you use.  Like Sgt. Shultz - "I know nothing" when it comes to solar but am trying to think ahead for when it might be put into actual use.   

[MountainDon]

... there are TV's made for RV's that run on 12V DC -- .

There are some small LED/LCD TV's sold for home use that come with a power supply much like those used with laptops, except they put out 12 VDC. One of those are easily used direct off 12 volts. It may be difficult to ascertain if a particular TV uses a power block or not so you may have to dig or visit stores to check in person.

Beware of keeping the polarity correct though as making an error can blow some parts inside the TV. They are not meant to be user/owner repaired but if you know what to look for and can solder you can.

[NathanS]

As far as I can tell, the small LCD or LED TV that came in my trailer is just a regular AC current TV. Near the TV is a DC plug, and into that I plug some cheapo inverter (a modified sine wave) that I bought years ago. That powers the TV just fine. Also, when we would watch TV we usually also were running our antenna amplifier, some LED lights, and the propane fridge and gas detector.

When you aren't using the TV, unplug the inverter.

The Renogy kits on amazon are a good deal in my opinion. You could probably start with a 100 watt panel kit for charging your batteries, and then add a second panel if you don't have enough sun.

For batteries, it's hard to go wrong with two golf cart batteries in series. Just make sure they are ventilated to the exterior - when they're charging they produce sulfur gas.

Even splurge and get the 200w kit. $340 hard to go wrong.

https://www.amazon.com/Renogy-Monocrystalline-Solar-Starter-Wanderer/dp/B00BCRG22A/ref=sr_1_1?ie=UTF8&qid=1475100413&sr=8-1&keywords=renogy+solar+panel+kit

[MountainDon]

they produce sulfur gas

...actually the danger is from the hydrogen gas, plus oxygen that charging produces.  There also may be some "acidy" fumes or mist expelled from the cells because of the rapid bubbling under some charge conditions. That can be harmful to electronics and is not a good thing to breath. So venting is a very good idea, essential IMO. As well do not have the battery charger or an inverter in the same space as the batteries.  All the preceding is specifically aimed at flooded lead acid batteries; the ones with removable caps.

Hydrogen is extra dangerous as it is explosive from a lower explosive level (LEL) of 4% to an upper explosive level (UEL) of 75 % (by volume not weight).  Gasoline which pretty much anyone considers very dangerous has a LEL/UEL of 1.2 / 7.1.  Not too many things are worse than hydrogen; acetylene is @ 2.5 / 100%. 

LEL/UEL table

[Dave Sparks]

Hey Don    People should be scared of build-up of hydrogen gas in small spaces. The OP here is in a tree house, I think...
The building code usually is very forgiving of batteries in a garage or a box that is power vented during the time the battery is at elevated bulk & absorb voltages. Just want to balance that charging is really not a big deal in large or ventilated space.
Even sealed batteries must have been thought about,  if there is a failure they can easily vent and a Hindenberg can happen in a small space.

I worry more about some of my clients who use sealed AGM batteries because I have warned them about this and they often are using them in small remote spaces that may not get looked at often. They tell me there is a high and low screened opening but I often do not get to XYZ country. I think they have swallowed the cool aid about being sealed. At the minamum they need a detector or an AUX controlled power vent in a 2' x 4' x 8' closet on an outside wall. I used some of your bat box ideas for keeping cool in hot climates with conditioned space air coming in and using the aux for bulk absorb in my battery closet.

Ok back to the scanner as yet another wildfire has stated. We have 12 in California now and 3 are going to burn all summer into late October

[MountainDon]

Good note about sealed batteries.

Re: 

wildfire ....  3 are going to burn all summer into late October

I've been told that here in the Jemez the natural order of things, before the white man came,  was that fires would start from lightning strikes in July / August. Most would be extinguished by accompanying rain but others would continue to burn across the landscape, meandering here and there until snow fell.

[Dave Sparks]

Good note about sealed batteries.

Re: 
I've been told that here in the Jemez the natural order of things, before the white man came,  was that fires would start from lightning strikes in July / August. Most would be extinguished by accompanying rain but others would continue to burn across the landscape, meandering here and there until snow fell.

All 3 of the fires I am talking about were caused by humans and at least one was sub-human. 
We did not get any lightning this summer (weird?) only the Sierra Mountain winter storm lightning that happens on 1/3 of the storms.

[glenn kangiser]

A small battery set up, minimum 2 to 4 golf cart batteries and small inverter, preferably sine wave and a few hundred watts of panels with a regulator can be useful for a lot of things.  I helped a friend set up a small system with 400 watts of panels and he uses a small chest freezer converted to fridge with an external thermostat control, lights and tools as well as powers a lot more occasionally before he has to add generator power.