12V Camper System Questions

[Dave.E]

I am building a truck cap camper on my Tacoma. Just figuring out the final electrical details now.

It's not going to be anything fancy, just a solar panel, charge controller, 12V battery and inverter. Any electronics will be powered by a usb port on the charge controller or inverter 110v. Nothing hard wired.

I have two questions:

1 - Is it possible to charge the batteries from the DC 12V outlet on the truck? I want to be able to charge it while driving. The voltage will be too low to charge the battery directly. I am thinking about using an old DC cord and wiring it with a boost converter to step up the voltage to 16V or whatever the panels are outputting. That way I could put it directly into the charge controller. Wired up with a selector switch could choose either solar or truck DC to charge the battery

2 - What kind of batteries are best? I can get 6V non sealed deep cycle batteries in decent shape for free. The whole un sealed thing kind of sketches me out as they discharge gasses when charging and I'm sleeping beside it.

Thanks!
Dave

 

[calicamper]

I am building a truck cap camper on my Tacoma. Just figuring out the final electrical details now.

It's not going to be anything fancy, just a solar panel, charge controller, 12V battery and inverter. Any electronics will be powered by a usb port on the charge controller or inverter 110v. Nothing hard wired.

I have two questions:

1 - Is it possible to charge the batteries from the DC 12V outlet on the truck? I want to be able to charge it while driving. The voltage will be too low to charge the battery directly. I am thinking about using an old DC cord and wiring it with a boost converter to step up the voltage to 16V or whatever the panels are outputting. That way I could put it directly into the charge controller. Wired up with a selector switch could choose either solar or truck DC to charge the battery

2 - What kind of batteries are best? I can get 6V non sealed deep cycle batteries in decent shape for free. The whole un sealed thing kind of sketches me out as they discharge gasses when charging and I'm sleeping beside it.

Thanks!
Dave

How much power do you need to use? One battery is generally better than two which case just stick with a 12volt battery option. First thing is sorting out what power needs you need. I built a 50 caliber ammo box power system for my small tent trailer sounds sorta like what your thinking. I'm using an 18amp hour sealed 12volt battery which fits inside the 50caliber ammo box, inside the box I have a solar controller which is designed for off grid parking lot lighting - it has a 20amp output side for the lighting. In my case I have the controller managing both my input charge from two 10watt panels but my power needs are max about 5-8amps for about 25ft of LED lighting, an ATV LED spot light and a small charging hub for USB devices. I've been using it all summer 4+ camping trips and its worked just fine. #1 thing is knowing what your power needs are then your questions can be answered. Total cost for my set up not counting the lights and such is about $150.

 

[Dave.E]

How much power do you need to use?

Phone charge each night. Maybe a laptop charge or two. Thinking 20 Ah will be good. Can always get a second one wired in parallel if I find I need more capacity later on.

 

[calicamper]

Phone charge each night. Maybe a laptop charge or two. Thinking 20 Ah will be good. Can always get a second one wired in parallel if I find I need more capacity later on.

Thats what we built ours for.

This was one of the videos I loosely based mine off of
https://www.youtube.com/watch?v=sXPs0hypsWI

Here are my Amazon purchases to give you a mental picture of the elements


The box
https://www.amazon.com/gp/product/B000J4HXUC/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

The brains of the battery management and by running the power load through the load side it serves as the cut off at 11.4 volts to avoid damaging the battery etc
https://www.amazon.com/gp/product/B00NCTST4U/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

I used this little fuse block and ran plugs off of it for the solar, lights and my little charging hub
https://www.amazon.com/gp/product/B00QMTAZ1W/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

So the power / load line from the controller is tied to the fuse block
Then the neg/ground from the load side of the controller is on my little ground bar
https://www.amazon.com/gp/product/B002FQKSKO/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
All the grounds from the powered items lights, and charging hub are screwed to my little ground bar which is "ONLY" tied to the load side ground of the controller.

The battery connection is only the battery connection to the controller no other connections are made directly to the battery.
So everything interfacing with the battery is being run through the controller. This controller is pretty slick in that it gives you your battery charge status, gives you your solar output status, gives you your load # ie how much draw your pulling from it etc. I did place at 15 amp fuse on the power feed from the controller to the little fuse block as a safety to prevent exceeding the 20amp output limit on the controller. They sell another one that has a 30amp limit, but so far my light use all summer hasn't exceeded 8amps draw at anyone time. So my little 20amp limit seems to work OK for us. The really bright ATV LED spot light only pulls 1amp and we typically only use it during night time arrivals and need the light to back up in the dark and set up in the dark etc. The multiple sections of LED strip lighting on switches combined only use about 3amps when all of them are turned on at the same time which generally never happens given one light is in my storage box.

This is my little charging hub which is not wired to the box, I plug it in to a fused power point on the box when I need it to charge phones, ipad go pro laptop etc. I snipped the stupid 12volt cig socket plug off of it and put RC Helicopter battery plug on it and the power source end and just plug it in when we need it. My little LED lighting stuff is plugged in using some cheap Automotive plugs.

My charging hub
https://www.amazon.com/gp/product/B00L14B292/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

All of the power management stuff is bolted in the ammo box. Battery is velcro stuck in the box, the ground bar is bolted in the box, the little fuse box is bolted into the box and the controller is in the box also. My two little solar panels I just unpack them and set them out once we set up camp. In my case I bolted my ammo box to my trailer but in your case you could leave it so you could move it around and out of your way etc.

My battery
https://www.amazon.com/gp/product/B00A82A3RK/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

 

[Dave.E]

Thank you for the detailed response!

Do you have any suggestions for charging the battery from the truck's DC outlet? I'm thinking that a boost converter to step up the voltage will do it.

 

[calicamper]

Thank you for the detailed response!

Do you have any suggestions for charging the battery from the truck's DC outlet? I'm thinking that a boost converter to step up the voltage will do it.

I didn't research that part - my initial thoughts is that in theory you could connect the solar source to the 12volt plug source and the controller would manage the charge process. You need about 14volts or more for the controller to charge the battery. A inverter doesn't make sense given your taking 12volt source converting it to power another 12volt charging process. Its better to just figure out if you can feed the controller 12volt power from the vehicle power drop.

In theory the controller shouldn't care whats giving it voltage as long as it doesn't exceed 20amps. My two little 10watt panels under full sun ideal conditions typically generate 15-16 volts and almost 2amps. I have yet to run into a situation were they don't bring the 18ah battery back up to full charge after our overnight power use. Even cloudy coastal CA and not being overly cautious with power use we were fully charged up by 3pm each day. That was with charging an Iphone, Samsung Siii and a Ipad, along with using our lights and I think my kids actually watched a movie on the DVD player one afternoon which was also plugged into the power hub.

I haven't charged a lap top on it yet that would require my inverter and probably pull about 10amps which case the battery capacity is only 18amp hours so we would only get maybe an hour and a half of charge time off the battery with no external power source.
If charging a heavy laptop is needed I would probably opt for a 100watt panel and charge the lap top during the solar/day hours to reduce the battery burn rate vs say night time charge without any solar input. Or just move to a heavier larger battery with more capacity etc.

 

[Dave.E]

How would you recommend charging from the car? Ideally I would like to avoid routing cables as the camper won't be permanent.

 

[robgendreau]

You could probably charge the house battery most easily from an ignition-on circuit; maybe you already have a cig lighter that fits the bill. Fuse it. It's not ideal, in that it's not a smart charger and just throws about 13.8 at the battery, but it's how many trailers, RVs, etc do it. Smart charging just doesn't work much since the car is on/off too often, etc. Also, when the solar and car circuits are connected, the solar controller/charger can't accurately read the battery, so you'd lose smart charging there. But usually this isn't an issue.

Voltage drop usually isn't an issue, since your car's voltage is moving around a bit anyway.

Routing the car electrical through the charge controller won't work; it won't even output if it's sensing 13.8v in most cases.

 

[4x4junkie]

I can't see any factory 12V outlet providing near enough current to charge a camper battery, there's nearly always too much voltage drop in the factory wiring going to it (anything more than about 0.5V significantly reduces the charge current going to the camper (aux) battery, prolonging it's charge rate).

A Tacoma of any vintage should have a decent alternator (outputs approx 14.5V or so), so there should be no need for things like boost converters, etc. to be able to charge the aux battery, all you need is good heavy-gauge cabling to the battery that has minimal voltage drop. This should not bother your solar controller either. When it sees the voltage coming in from your alternator, it should automatically shut itself down (and then resume charging from your solar panel when you shut the engine off).

What I would suggest is a setup (using a relay to isolate the battery when the engine is off) running straight from your truck's battery back to your aux battery using good cabling (#6 would likely be ok though #4 or even #2 would be better). Have a good 100A or better heavy-duty connector on it (Anderson Power Pole, etc.) allowing you to easily disconnect the cable when you remove the camper.

This thread should have some good info about building a relay setup... There are several commercially-made relay isolators you can buy also (just avoid the diode-type isolators (these look like a big finned heat sink), they don't pass enough voltage to charge a battery well).

 

[fog cutter]

.... It's not going to be anything fancy....

uh huh. i'm having this engraved on my tombstone!

 

[228B]

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