12v, 24v, Solar, Shore, Batteries and more!!

[Doc2012]

Ok gents. More of a lurker here, and enjoy reading the piss out of everything you wonderful guys have posted. I did search, but really didnt see anything that would answer my questions...

Heres my quandry.

I'm building a trailer.

I want power. (Duh)

Bewteen 12V, 24V, Battery options, Shore power, and all that crap, I'm completely mind blown.


things I plan on running in the trailer:

Water pump for shower(more than likely a 12v, possibly a 120v)
4-6 120V outlets for charging stuff, possibly small TV/DVD player(for the kids)
Lights on the inside(already there, just need to convert to 12V{You'll see what I mean in a minute})
Lights on the outside(more than likely 12V Cheapo Baja, possibly LED if I can ever find a damn housing so I can build mine)


As far as stuff that's going to need power, that's about it. I plan on having some other stuff on the trailer, but that will be using LP.


I've read the Camper Battery thread. I've searched and read the builds. There's great info out there. I've googled the snot out of this topic.

My plan WAS to use three charging options: Truck, Shore(if available) and Solar.

I've pretty muched nixed the Solar idea, for the simple fact that I would need a lot of panels to charge the battery, and I live in NC. Not a whole lot of places to go camping and wheeling without trees.

So that leaves me with my two main charging options: Truck and Shore. POSSIBLY a small generator, but don't want something loud, as it would be running all night...

I know I need inverters, converters, and all that jazz.

My question, for you folk, is what KIND of battery should I use?

I've seen people talk about 6v golf cart batteries, 12V systems, hell, I've seen 48V banks and all that crap.

Amp Hours is something I need to take into consideration, I know this. I need to figure out how many amps I'll be drawing, ect.

I'm thinking the 12v, wired in parallel, 2-4 batteries for the whole shebang.

But WHY not the 6v or the 48v golfcart batteries(guessing not the 48v because of the fact, that its a 48v.)

Help please.....

 

[Joe917]

Why not 6volt system? Try to find six volt pumps, inverters, fans etc.
The 12 volt system will give you the most options, there is just more stuff available. A 24 volt system will allow smaller wire runs but that is probably not an issue for a small trailer.
Don't nix the solar too quickly, a small panel will not bulk charge your battery bank but it will do a very good job of the absorption charge.
6 volt golf cart batteries are by far the best bang for the buck, they need to be well vented and you have to check the electrolyte level regularly. They will outlast AGMs.

 

[unseenone]

This all depends on your budget, and how much weight you are comfortable carrying. You could do for example 4 6 volt 400Ah L16 AGM batteries. Configured as 12 volts, you will have 800Ah of storage, configured as 24v you would have 400Ah. Bear in mind, that most, but not all stuff will run on 24V. for the items that will not, you can use a Vanner Battery Equalizer which taps off the 24V system to provide a smaller 12V system (A separate 12v battery).

Remember, if you use an inverter, if you run a 24v system, the advantage is lower amperage, so you can use smaller wire, or have longer runs. You truly get what you pay for with inverters, good ones are expensive. You'll need to carefully weigh the options of how many watts you plan to run, and add some for the inevitable larger widget you want to run. Stick with a pure sign wave inverter so you don't run into things it will not run.

If you want to engineer it to the max, then you might consider installing LED lights.

If it is at all possible, I would avoid inverting where you can, for example 12v power adapters for laptops, phones, battery charges and so on.

It would be worth running a battery system, such as a Traxide kit, which are made to accommodate dual vehicle batteries, or triple or more, and have the proper provisions to connect the trailer to the vehicle system, so you can have your caravan bank, as well as the vehicle bank(s). There are also less expensive battery isolators that will isolate your caravan bank unless the vehicle is running, which might be a consideration of budget is an issue.

While solar might not do much for you, if you have the roof space, there will be some benefit. I would avoid kits, and consider building it yourself. There is another thread here of a fellow in Scotland I think that did a nice build out, which would be beneficial to you.

I like the AGM, everyone has a preference, I also have 6V golf cart batteries in another installation, it is a bit more of a hassle to maintain it.

Finally, you can get a Marine water pump with a pressure switch, I am sure pretty much the same as many campers, tap it off your tank, and you will be in business there.

 

[DiploStrat]

Let the Sun shine in!

Couple of comments:

-- Figure your load. Don't forget that even LP heat requires power for the fan. If you can't come up with another figure, estimate 100Ah overnight. (That is a bit less than I use in my Tiger, but then I cook on electric. You may use a lot less, unless you plan to run an air conditioner.)

-- Take your overnight power number and multiply it by the number of days that you will not run your engine or get any sunlight at all. I use three as my planning number. YMMV

-- Take that number and double it. The rule of thumb is that lead acid batteries should not be discharged to more than 50%.

This is going to give you a number between 100 and 600Ah for the size of your battery bank. If you are using a trailer that won't see that much bad road service and has the room, you can probably save a lot of money by going with conventional, vented lead acid batteries, as opposed to AGM batteries. Handy Bob is quite eloquent on this subject: http://handybobsolar.wordpress.com

My plan WAS to use three charging options: Truck, Shore(if available) and Solar.

I've pretty muched nixed the Solar idea, for the simple fact that I would need a lot of panels to charge the battery, and I live in NC. Not a whole lot of places to go camping and wheeling without trees.

This is still what you want to do. I have read all of the many posts that tell me that solar power is useless east of the Mississippi, then I go check the gauges on my Tiger, parked under the trees on a cloudy day in Virginia, and I am still getting 2A of charge. I could get more, but then my batteries are at full charge. Granted I have a 500w solar array, but I have been amazed by how much charge it puts out. And it charges from first light to sunset.

To get a decent charge to a trailer you will require huge cables and some form of really BIG disconnect. And you want to do this as a modern truck alternator, running at over 14v, is a great source of bulk charge, that is the high current needed to get you to above 80% charged. But, depending on how much current you use overnight, you are unlikely to ever drive long enough to fully charge your batteries. And this is where a solar kit is invaluable, especially during the acceptance/absorb stage of charging when you don't need that much current, just long term voltage.

Scroll down on this link for some thoughts on RV systems and some nice, big pictures: http://handybobsolar.wordpress.com/2014-solar-ideas-batteries-other-things/

Finally, while I never have to plug my Tiger into shore power, I do have a modern inverter/charger and you should have one too.

Hope this is helpful.

 

[4x4junkie]

Agreed, stick with a 12-volt system (if using 6V GC batteries, you wire two of them in series for 12V, then if you need more capacity, wire a 2nd pair-of-two-in-series in parallel with the first pair-of-two-in-series, and so on).

Also agreed, don't be so quick to discount solar... especially if you keep your panel(s) portable. A portable setup allows you to place the panel away from the trees and aim it directly at the sun for maximum power harvest.
The loads you mention are fairly light, 100-150Ah of battery capacity + 100-150W solar setup I would think should be able to maintain that no problem (if you add a 12V fridge, then bump it up to 200-300Ah + 170-250W solar).

Edit:

Wow, this thread got busy quick lol

I didn't think of the furnace fan... That right there is a power guzzler for sure (the one in our motorhome's furnace draws about 10 amps it seems). That thing running for a total of a couple hours a night no doubt can put a good dent in your power reserves.

Maintaining it purely by solar I don't think is out of the question though... two 100W panels set up as portable should still keep up with it no problem.

My setup:

I run two 12V Delco Voyager deep-cycle batts in parallel (190Ah total, I recall), solar is 170W. The panel folds up like an oversized briefcase (I put hinges + a carry handle onto two 85W panels) and straps down to the roof of the vehicle while underway. Easily keeps up with a fridge, playing the stereo all day (low-medium volume) + a few hours use of 10-20 watts of LED lighting at night.

 

[Doc2012]

All the comments thus far have been VERY helpful.

I can't believe I forgot to add that i do plan on running some kind of an AC unit. The main piece of the trailer I plan on using does hold heat VERY well.

That being said, I completely forgot to add pictures to what I was talking about using.

SO, here they are.

I currently have a M116A2 Generator Trailer.

I've also got a M996 Ambulance body. (Need to go pick it up. Work sucks lately.)

Anyway, onto the pics....

The pics are a M997, but basically the same as the M996.

Great space, fairly light weight, and already built. Just waiting to be customized.


Sent from my PRC-119 using morse code.

 

[4x4junkie]

I can't believe I forgot to add that i do plan on running some kind of an AC unit. The main piece of the trailer I plan on using does hold heat VERY well.

That changes things... A lot.

It'll definitely be tough to run a A/C unit off solar (you'd probably need a KW in panels minimum just to overcome the power draw of even a small A/C unit while still replenishing your batteries from last night's usage).


Regardless, I would probably still stick with a solar plan for everything but the A/C, and then consider the A/C a luxury that can be afforded when hooked to shore power (or by running your generator). On days you don't need the A/C (or when a simple fan can suffice), the solar should be able to maintain the rest of your power needs.

You running a 12V or 24V system in that rig? I'd probably suggest sticking with an inverter & battery configuration that matches whatever your rig's voltage is, as that will allow for direct charging of the batteries from the vehicle alternator if desired.

 

[DiploStrat]

Don't need no Genset!

But, if you do want to run an air conditioner, you will need:

-- Good insulation.
-- A small, 6k BTU or smaller, air conditioner, properly installed and vented.
-- A minimum 2800w inverter.
-- A LOT of batteries, 600Ah is bare minimum.
-- Proper connection to an alternator(s) of 150A or more.
-- Roughly 100w of solar per 100Ah of battery bank.

I know, I do it. As far as I know, the only campers available off the shelf with an air conditioner and no genset are the Earthroamer and the Tiger. The Road Trek E-Trek comes close, but they mount a genset driven directly by the truck engine.

It can be done, but it isn't easy. And I still don't know how many hours of endurance I can get. FWIW: Estimate 15A draw for the fan and 50A draw for the compressor. Starting current is on the order of 250A DC. That's a lot, hence the monster inverter.

 

[dwh]

For A/C you could run a trucker's mini-split sleeper unit. Since anti-idling smog laws, there are many different units available in different sizes. Most use a Danfoss variable speed DC compressor which is pretty much the most efficient there is.

http://www.dometic.com/enus/Americas/USA/Truck/HVAC-Solutions/products/?productdataid=92541

You'll still need too much insulation, too much battery and if you want solar...too much solar.

Or a decent little genset, which personally, I wouldn't leave home without anyway. I don't run solar because I like to park in the shade and can't be bothered messing around with portable solar. These days, my idea of "setting up camp" is to pull up and park. Maybe break out a folding chair, but if there's a picnic bench, I usually won't even do that.

 

[unseenone]

There are some decent AC units made for this sort of thing running at 12/24/48 volts. Something like that might be a consideration. Was that Ambulance originally wired at 24volts? If you switch to 12 the wire may not be big enough so may need to be replaced.

The units here are going to be way more efficient than AC powered systems.. There are additional options on the military tab worth looking at.

http://www.dcairco.com/product/trucks-airconditioning

 

[Doc2012]

The ambulance was wired for 24v. Just like the HMMWV.

The M997 variant has an AC/heater. The M996, mine, doesn't. It also doesn't have the CBRN equipment.

I plan on using the space above the "cab" for water storage. Potable and shower water, which will probably be the same tank, seeing as how I'll probably just fill up from the garden hose before I leave. If I need to, I can go to a stream to fill up. I've got (2) 20L water cans, and (2) 20L fuel cans, as well as working on an extended tank for my 4Runner.

I'm currently running a CS144 alternator out of a Caddy. The whimpy stock 80amp alternator crapped out on me, so that was a great time to upgrade. The CS144 puts out 140amps at idle.


Why would the wire not be big enough to support the 12v system? Mainly just the lights that will be running off the 12v, so if I just changed the lights to 12v, that wouldn't work?

Guess I need to brush up on my wiring and stuff as well. Didn't realize that the 24v wiring wouldn't support the 12v. Always thought that going from 24 to 12 was ok, but going from 12 to 24 would need to be upgraded?


Sent from my PRC-119 using morse code.

 

[soulpatch]

Higher voltage, lower amps = smaller wiring runs.
I've been wrong before, though.

 

[unseenone]

I can't say for sure, if they used the "standard" 12v wire, or tried to save money, and used smaller wire. As mentioned by soulpatch, 12v runs at a higher amperage to achieve what 24v does at less amps. Like I was saying on the inverter wire, there is a significant allowable size reduction in wiring at 24v vs 12v. You may very well be able to use the existing wire, just check the wire size, and if possible, verify with the Mfr. that it is fine.

It looks like a neat project for sure..

You'll find a useful chart on this page, to give you a general guide on wire size, lengths and amperage. You might also consider using Ancor Marine Grade Duplex for any smaller additional wiring you add. It's got an extra flexible, abrasion and vibration resistance as well as an extra covering unlike traditional DC wire. Keep in mind, every wire manufacturer should be able to provide their own specs based on the wire.

http://www.jamestowndistributors.co...&title=Maintaining+Three+Percent+Voltage+Drop

 

[cwadej]

.

hehe. I used to live quite close to there...... right behind building 1.

 

[Doc2012]

hehe. I used to live quite close to there...... right behind building 1.

Building 1?

As in the General's building?

This pics were taken at French Creek, behind MEDBN.

The growth of the base in the last 5 years (been here since 2008), has been insane.