Off the Grid

Fantail · April 5, 2011

Anyone use 12v alot when your camping?

I'd like to start a thread discussing what we do without 120v. First off - does anyone familiar with solar power know if you can keep those panels clamped to the battery while drawing from it at the same time without a charge controller? Not so much for lighting, I mean we have our lanterns, battery puck lights, etc, but more along the lines of camper ventalation fans. Modern campers have appliances such as refridgeration that have dual power sources but I tend to think these 'set-ups' are designed to plug-in somewhere.

I'm redesigning an older camper because it was cheap enough, and I won't need the appliances, aside from the stove. So they are gone and I installed shelves & slide out cooler storage. So I should be able to get away with 1 propane keg. That leaves 1 'luxury', the stove, but above it on the wall there was a 120v vent. Keep in mind I removed all the 120v jazz. I do have a 12v fan similar to the ones you can buy at auto parts stores. The plan: I have screened & framed the vent so I can clamp this fan and use it, fits good suprisingly. Also be able to slide it out to oscilate inside. 1 fan, dual use, replaceable. I can hook it up to something holding a 12v tool battery, or plan B would be a car battery or deep cycle. But I don't want to become dependant on running the Jeep to keep that charged unless I need to. Enter the 50$ solar panel for a trickle charge of sorts. Which opens other possibilities.

Could use a new battery for the Jeep, while the one it has isn't dead if I eat the core cost then I can recycle it that way untill such a time demands an upgrade. I'll also have my inverter with me but thats just for recharging the 18v tools & aa-aaa batteries.

One thing I like to do is cook using the pit but now I'll have the camper stove & spare single burner for back-up. It'll be nice for coffee while gearing up before sunrise or perhaps being stuck inside from a downpour. The whole idea is not needing to leave camp in case one system bombs.

Oh yeah so I'm in harborfreight the other day and spotted those wind-up led lanterns. My first thought was why do they make them look like a regular lantern? They are designed for 20 minutes on a change. But they don't look like they are built to last. Anyone have one of these lights?

Doewhacker · April 5, 2011

Let me start by saying this is way off my scope of expertise but I will try to add my two cents.

With my camper I can have the battery hooked up and the camper plugged into a power source at the same time but it also has a inverter in it so I don't know if you could have the solar panels and use the battery at the same time. I don't see why you couldn't but again what do I know..haha

How much power could a fan draw off a battery in the first place? I would think a car batt could last you a while and you could charge it when not in use at home. If that doesnt work then I'm sure the solar panels would be able to provide enough juice to trickle charge that bad boy up while you are out at camp.

I would test what ever idea you come up with to see how long it last you at home, but Im guessing you are smart enough to figure that out any way if you are smart enough to come up the ideas you already have.

Doewhacker · April 5, 2011

Here's a place that sells the solar panels, I see no reason why this won't work just fine for you.

http://www.siliconsolar.com/12v-automotive-solar-battery-charger-4_8w-p-16652.html

How are you going to run the power from the batt to the camper? Or are going to run it directly to the fan some how?

I know I can run certain things in mine straight off the batt if I chose to, like outlets for coffee makers.

G-Man · April 5, 2011

I woud run the solar panel trickle charger to a deep cycle 12 volt batt. and then run off the battery you will get the ability for a much longer draw from the deep cycle batt vs a car battery. My friend uses this setup at his cabin (no electric otherwise) he can run his 12v lights and fan off the battery all day and night,and the trickle charger is hooked up to the battery at all times and has a cut out when charged. not sure of the make of the solar charger with cut out but i can ask..

Fantail · April 6, 2011

Deep cycle batt would be the better option, absolutly. After buying this camper & a rear-tine tiller was just looking to save on the budget for now. Those optima's are 250$ or so. I would be interested in what the cut-out is about.

I thought store the battery inside the camper if it's safe. Up front there's compartments under the seats, like most of these things have. One side had the old water tank. Now gone that leaves a spot I could install a plastic battery box. This spot also has a 2" or so opening to the outside (where the water fill was) that I can rig and seal off for cables to the solar panel. Either that or part of the rear compartment under the bunk. But there I'd have to make an opening.

From inside run a pair of good wires up and over in some conduit to a point probably near the kitchen to a box. From there I would think to fuse the + and be able to allow for expansion. From that point be able to run a toggle to the fan.

Culvercreek hunt club · April 6, 2011

Any charging battery has the potential of giving off hydrogen.vent any area you store to the outside.

I am running our cabins 12 volt system a couple of ways. I got a45 watt solarpanel andcontroller from harbor freight. It works freak. Has ports to draw power direct from the panels and any surplus goes to batteries. You most definitely can charge and draw off your battery at the same time. Out lights and the Waterpump both end up running during the charge cycle. We also have a charger for our generator if we need a top off and mother nature hasn't been keeping up her end of the bargain.

NYDeer · April 8, 2011

Hit wally world, Everstart MAXX grp 75 deep cycle, was under $100.. and has a 18mo or 2yr replacement warranty.. BUT these are vented bats, so installing inside is out.

nyantler · April 8, 2011

Any charging battery has the potential of giving off hydrogen.vent any area you store to the outside.

I am running our cabins 12 volt system a couple of ways. I got a45 watt solarpanel andcontroller from harbor freight. It works freak. Has ports to draw power direct from the panels and any surplus goes to batteries. You most definitely can charge and draw off your battery at the same time. Out lights and the Waterpump both end up running during the charge cycle. We also have a charger for our generator if we need a top off and mother nature hasn't been keeping up her end of the bargain.

Culver.. i have been looking at that same system for my cabin....I want to run a 120v system with inverter and all.. i heard that 45 watts would be enough for just lights and a 12v water pump... for weekend use... what do you think? I was thinking about linking 2 deep cycle batteries for the system.

Culvercreek hunt club · April 8, 2011

We run two batteries as well and get a weekends use easily. You want to size your system so you never take the batteries under 50%. Inverters are a no no unless you really have to because there is energy loss in the conversion. If you were just going to run lights and a pump you could probably get by as you described. I am on the road. But when I get home next week I will PM you a link to the 12 volt pump and lights we bought. We only have electric lights in bathroom and bunkroom and the most they get used isduring a shower. The main lighting is propane.

Culvercreek hunt club · April 8, 2011

I am still looking myself but an awesome option is finding good used golf cart batteries. They are 6volt so when a pair are hooked in series you get great 12volt capacity.

nyantler · April 8, 2011

We run two batteries as well and get a weekends use easily. You want to size your system so you never take the batteries under 50%. Inverters are a no no unless you really have to because there is energy loss in the conversion. If you were just going to run lights and a pump you could probably get by as you described. I am on the road. But when I get home next week I will PM you a link to the 12 volt pump and lights we bought. We only have electric lights in bathroom and bunkroom and the most they get used isduring a shower. The main lighting is propane.

Thanks Culver that will be great... i want AC power for lights and outlets though.. so I'll need the inverter... I would be willing to add an extra battery to handle things if need be.. i just am curious about a 45 watt panel being enough...

Culvercreek hunt club · April 8, 2011

I can walk you through the calcs to make sure. Pretty easy. Biggest thing is having a controller where you have capacity to add panels

Fantail · April 11, 2011

Ok have been rethinking the solar power plan a bit. A marine battery box is cheap, 100$ deep cycle, cables etc., is still less expensive then one of those optima's. Will still go with a 15w panel & a meter-tester to keep an eye on things. Salvaged a dc light for back up but for now I'm mainly concerned with powering the fan. Want to know what a smaller 1 panel system can do before I invest or need upgrades.

Recharging power tool / batteries; same way as before with the inverter & run the Jeep I guess.

Culvercreek hunt club · April 11, 2011

ok...Let me see if this helps you guys. you have to figure out your usage that you anticipate. Add up the total watts of power you will need for eaach of your applications.

a 60 watt bulb on a 12 volt system is 5 amps...so it will burn 5 amps of power from your battery if used for an hour. IF you are running an inverter you have to add 10-20% depending on the inverter (cheaper inverters have higher loss). Let's use 15% for this. the bulb will use 5.75 amps for an hour.

For your total load calc... list your wattage for each component and divide it by 12. multiply each item in that list the anticipated hours of usage.

60 watt bulb / 12 volts=5amps/ hour x 5.5 hours usage = 27.5 amps (inverter loss gives you 31 amps)

total all you amps required and multiply by 2 (so draw down on battery is only 50%) and that is the battery storage capacity you will need.

now for the panel. a 45 watt panel will give you 3.75 amps an hour into your storage. If you anticipate a 6 hour light day (figuring clouds and the fact that the panel can't track the sun to maintain the optimum angle) you get 22.5 amps going back into your battery each day.

If you used the system every weekend and didn't during the week, the 45 watt panel shoudl give you 112.5 amps back into the system.

I am running 2 each 100 amp deep cycle batteries (200 amps). that gives me 100 amps of usage.

I think every one doing this should have a small gen set to help charge if the batteries drop. and I just saw a cheap 800 watt gen for sale at harbor freight for 90 bucks. That would be enough to run a charger if the batteries dropped. If you run the batteries down repeatedly you will ruin them.

Here is the link to the 12 volt water pump I use. I draw out of a 275 gallon tank that collects rain water from the roof for non potable water.