Battery mounting location?

[dwstucke]

I've finally got all the components to install a 12volt system in our Airflyte. I'm planning on mounting the battery box centered on the tounge for now as it looks to be the easiest place to mount it securely. If I decide to carry a propane tank at some point though I'll have to relocate it.

Can anyone share photos showing how they have their battery box mounted? I'd be interested in seeing tounge installs both with and without a propane tank.

- Don

[universalexports]

here is an interesting setup, 1 propane tank and 2 batteries.

www.tincantourists.com/classified/showproduct.php?product=4283&sort=2&cat=3&page=8

[vikx]

Here's one using tent trailer tie downs and a regular two tank plate.

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[vikx]

Here's a similar mount:

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[vikx]

Here is one with the battery dropped to the bottom of the tongue rail and the tank in front:

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[vikx]

This is a picture of ears cut in the tank plate to allow more clearance for the battery box:

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[dwstucke]

Thanks, these photo's are just the thing I was hoping for, a variety of solutions to compare. Based on these I think that I'm going to go ahead with the easiest solution for now, as I've got the box placed in my photo attached.


If I leave some extra wire length from there I could graduate a 2-tank tank tray for side-by-side solution. Ideally I'd like the propane tank to sit on center as I think it looks better but I don't think there will be enough room between it and the front wall. I'll have to borrow the tank off my grill for a quick look.

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[avannoy]

What are the reasons for mounting the battery on the tongue, as opposed to somewhere inside the camper? It seems you could mount a couple of batteries under the bed area in the rear. Is it a weight distribution issue?

[vikx]

Dw-space is always an issue on the tongue. LOL...

Any battery can gas. That is why it should be on the tongue or in an enclosed, vented compartment.

[jessie]

Vikx, I thought that was the beauty of the AGM batteries... they did not off-gas?

[avannoy]

The Optima battery marketing says they don't off-gas so we were planning to mount them somewhere inside. But we'll research it more before we do that.

[vikx]

Yes, sellers will "tell" you the batteries don't gas-but no guarantee...

Definitely safer than wet cells but I don't want to take any chances.

[61shastacompact]

A little hydrogen never hurts....

[dwstucke]

Hmm, perhaps I don't want a battery at all.

Seriously though I know I know that I could spend a bunch more on a Optima or other AGM battery and mount it inside but even with that I think I would still vent it. I also like having the storage space on the inside for other things.

[Gone Kayaking]

I went ahead and put 2 optima grp 24 AGMs under the dinette bench street side. I am not worried about the off gassing issue, after consulting with folks who use them live aboard on their boats as well as two trailer resto folks here in ca (harps Rv and allies trailer). What I might have done differently is put them on curbside as the weight distribution seem like it would work better. No pic but you can look on my restoration post aguadream and find it

[bretso]

Thanks to all for posting photos. This thread helped me decide what I was going to do with the battery/propane rack situation.

I re-used the 2-tank propane rack and modified one side to fit a battery box.

I had some trouble locating the proper tie down rods for the remaining propane tank. The RV shops around here told me they all make their own tie downs from threaded stock (All Thread) and I should do the same. So I did - painted them white - now I'll probably find the proper brass colored tie downs the next time I'm in Walmart.

Does anyone have an online resource for ordering tie down rods?
I consider my white All Thread Rod a temporary piece of equipment.

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[cowcharge]

I've read that there are laws about the permissible colors one may paint their propane tanks, that they must be reflective so as not to absorb heat from the sun. Just wondering if you've had it filled anywhere yet. I painted mine white to be safe, and haven't had any trouble.

Batteries really only outgas when they are overcharged or charged too quickly, so if you have a good converter designed for a camper you should be okay.

"AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery." www.windsun.com/Batteries/Battery_FAQ.htm#AGM, or Absorbed Glass Mat Batteries

[bretso]

Jun 29, 2012 22:21:04 GMT -5 cowcharge said:

I've read that there are laws about the permissible colors...

Oh wow, I hadn't even considered that the color would be regulated. I guess I'll find out when I go to fill it. I'll report back. I have seen plenty of photos of painted tanks, some with the shasta z stripe, so I thought it would be OK.

[cowcharge]

If they're too dark they can heat up and blow their safety valves.

[vikx]

Beautiful work Bretso! I don't think the green tank will be an issue.

Modern RVs use two stage vented regulators, while most vintage trailers did not. Therefore, no "vent". I've actually seen LP tanks vent in extreme heat. A simple piece of cardboard will prevent overheating.

Proof or no proof, I keep my batteries outside or in a sealed, vented compartment. Just an extra measure of safety.

[cowcharge]

Vikx, I find it curious that you dismiss the danger of overheating tanks but worry about the almost-negligible threat of AGM batteries. Am I missing something? To me, 20 or 30 pounds of propane venting at 375 psi is a much larger threat than a few ml. of hydrogen that can only occur if the charging system or battery fails or is badly designed.

Bretso, if you want to check the paint color, park in the sun and put your hand on the white and then the green parts of your trailer. If there's no difference in the temperature, your tank is ok. If the green gets significantly warmer, I'd repaint the tank. What's the point of a pretty green tank if you have to cover it with cardboard?

[westend1530]

When I was getting my propane tanks re-certified the guy said that tanks painted something other then white often times blow because of heat. I don't know how often this actually happens but that is what he said.

My guess is that a dark colored tank, out in the sun, here in Atlanta over the last few days would have blown. It's been hot as hell

[safetybruce]

Been told steady exposure to 135 degree sunlight will only cause the compressed gas in a completely full cylinder to expand to 5% greater pressure than the max. fill pressure. I believe as a minimum all certified commercial cylinders have been pressure tested 35% over the maximum rated fill pressure. I've worked with hundreds of 300 cubic foot oxygen and acetylene cylinders in direct sunlight in temperatures up to 130 degrees in Dubai, and never had a direct sunlight heated only cylinder failure. Wouldn't paint a little blue rhino rv propane tank black, but would not hesitate to paint it the lightest color in the color scheme of my camper. And as mentioned have a pressure relief valve on it just in case.

[vikx]

I did not "dismiss" any issue... tanks rarely vent and the RV regulator vent is there for that very reason. In older trailers with an unvented regulator, it could be an issue. The tanks are not inside the trailer.

Gassing batteries are dangerous. I talked in person to an Optima representative at Camping World and he would not guarantee that Optimas would never gas. Therefore, I think they should be outside as well.

Common sense and all that...

[cowcharge]

Well, the code says they must be painted a "reflective" color. Whether anyone enforces it or not, who knows? I'd check with your state, as the laws can differ. And the regulator vent won't help if the tank valve's closed, but either way, who wants propane venting from anywhere? If you happen to be grilling or smoking at the time...

I tried to find some scientific data on solar heating by color, but could only come up with this chart on car rooftops: enerjazz.com/data/cartempsurf/
There are some damned high temps there.

I was also just reading a math-filled article on overfilling fires in balloons, which they say are common in cold weather due to the need to heat the tanks to a usable vapor pressure for proper performance. www.balloonlife.com/publications/balloon_life/9701/overfill.htm

"At room temperature (70 F) its vapor pressure is 375 PSI Gauge (the normal setting for the pressure relief valve) at a temperature of 162 F. Thus a properly working propane container, properly filled, can be heated to about 162 F before its pressure relief valve can be expected to open." Properly working, and properly filled, which is never guaranteed...
In the car roof chart, both red and dark silver reached 160 degrees in the upper 90s of ambient temperatures...

"From Figure 2 we can see that if a propane tank is filled 85% full of liquid it will become totally full when the liquid has expanded to 118% of the original liquid volume. If we filled the tank 85% full of liquid at 60 F, then this would require a final temperature of approximately 144 F. From Figure 1 we see that this is close to the temperature at which the vapor pressure of the propane is 375 PSI, at which pressure we would expect the vapor pressure to cause the high-pressure safety relief valve to open for two causes about simultaneously if we heated the tank to 144 F, first because the vapor pressure would open it, and second because the expanding liquid would open it."

It's not outside the realm of possibility that those types of conditions could occur with one of us filling tanks on a cool desert morning, and then parking in the desert sun, especially with a colored tank. Or filling our tanks on a Montana winter morning, and parking in the sun in Arizona the next afternoon. Liquid propane venting? No thanks!

I would still recommend that you test the actual color through measuring the temp difference between the sunniest part of your green tank and your white roof after a couple of hours in the sun.

[christtg]

So... I'm going to install a battery box on a piece of pressure treated ply, mounted on the gas tank cradle. The box comes with a strap and a pair of clips that the strap goes through. Those clips are supposed to mount to the surface (ply) per the instructions.. Couldn't I just drill holes in the bottom of the box and attach it to the ply with screws or would the metal screws cause a problem with the bottom of the battery? Is it not recommended to drill holes in the battery box in case the battery develops a leak?

[cowcharge]

The battery box was probably designed for a boat, so they didn't want holes to let salt water in. I'd be worried about the screw heads pulling through the holes under the weight of the battery. Even with big washers a bumpy road could crack the plastic. The straps would be much safer IMO.

[kto17]

I can't speak for RV tanks or old tanks, but the standard LP tanks you get from Home Depot etc have a pressure release built it. Don't believe me? Google it. That's why there is a sign on those cages that says no smoking! In the 90's I worked at HD in Atlanta. During the summer you could hear the tanks hiss when the pressure release opened. It would surprise me if those built in valves occasionally fail.

There may be regulations on color. I don't know, but why paint it dark? Your just wasting LP when it heats up and bleeds out.

Yes my Astrodome came with tanks painted gray! I keep them disconnected unless we are cooking. So far they haven't blown up in the Atlanta heat.