Dual Battery box

[gearhead]

We've had the Montana about 18 months now. When we bought it, I paid the dealer to install 2 batteries since we dry camp at races occasionally. They installed 2 batteries but only one had a battery box. They said they were out of boxes. Right. They finally mailed me a battery box, it was the same thing I could have bought at WalMart--no vent hose connection. So when I would think about it I would Google battery boxes. This week I saw where someone had used a Tupperware type box to put 2 batteries in. Long story shorter...I found a Sterlite tub at Walmart that would work for the 2 batteries. I found a PVC coupling that slipped in the existing vent hose. Drilled the tub lid with a hole saw, put a new hose clamp on the coupling under the lid, and tightened the clamp on the hose on top. A little 3M marine sealant and I think it's good to go. I did have a little extra room in the tub so I cut some treated 2x4 to fill the voids and keep the batteries from bouncing off each other.
If anyone needs a pic I'll get ya one.

[Steve S]

I think that if you posted some pics it could help others save a few bucks:)

[gearhead]

I think that if you posted some pics it could help others save a few bucks:)
Whaaat?? My technical writing skills are inadequate? LOL
It rained all day and a "blue norther" just blew in. It's down to 64 degrees out there! Have mercy on a brother.
I'll try to remember tomorrow.

[larry337]

Recently installed 2 6 volt batteries. I used the original vent hose, spliced it with a tee connector, bought 2 6 volt battery boxes that fit like a glove, a couple flanges and an extra hose. Total cost about $40. I wish the extra hose were black but white is what I found so no biggie.

[gearhead]

Here are pics. If you do this, find a box that has snap over type locks.

[gearhead]

Recently installed 2 6 volt batteries. I used the original vent hose, spliced it with a tee connector, bought 2 6 volt battery boxes that fit like a glove, a couple flanges and an extra hose. Total cost about $40. I wish the extra hose were black but white is what I found so no biggie.
I decided not to invest in a new battery box. I'll go to bigger batteries when I replace these in a year or 2. Maybe then.
I've got about $9 in the box and the PVC coupling.

[hankaye]

gearhead, Howdy;

How have you secured the Sterlite tub itself in place ?

Curious mind ...

hankaye

[gearhead]

gearhead, Howdy;

How have you secured the Sterlite tub itself in place ?

Curious mind ...

hankaye

I haven't yet. I plan on running a couple self drilling/self tapping screws with fender washers through the bottom.

The dealer didn't have either battery secured.

[Steve S]

Is the tube just free vented or do you have a small fan on it?

[gearhead]

Is the tube just free vented or do you have a small fan on it?
Its free vented through the factory hose and vent grill.
I have either been lucky or the issue of hydrogen off gassing isn't as serious as I understand it. My dealer supplied 2 batteries....one had a box made to connect to the vent hose, which the dealer supplied; but the second battery they installed was just sitting on the steel floor. The battery top cover with the hose could not snap down on its bottom half because the wires that connected to the other battery. So the batteries were basically just venting into the storage/generator compartment.
I am very aware of hydrogen characteristics (Olefins Hydrotreater) and dangers, but I'm not very knowledgeable of battery off gassing during charging. I assume the "lighter than atmosphere" hydrogen would want to rise to escape. I am familiar with Chlor-Alki process which is the same as charging a battery, in a scale many times over.
Lucky me, lucky us, I suppose.

[AnolaBob]

I have seen people go to great lengths to box and vent their batteries.

Could someone please explain the need for it as the storage area has plenty of holes for the air to enter and escape. I have two 12 volt batteries end to end with the hose loosely in the well they sit in. I don't think it does a thing.

I would think that TT's would have more trouble than 5th's as they have their black battery boxes in the full sun, sometimes.

Please advise.

Bob

[larry337]

I have seen people go to great lengths to box and vent their batteries.

Could someone please explain the need for it as the storage area has plenty of holes for the air to enter and escape. I have two 12 volt batteries end to end with the hose loosely in the well they sit in. I don't think it does a thing.

I would think that TT's would have more trouble than 5th's as they have their black battery boxes in the full sun, sometimes.

Please advise.

Bob

The issue is hydrogen gas, think Hindenberg. Its not an issue on a TT because the battery box is out in the open where the gas dissipates into the air. When the battery is stored in a compartment the hydrogen gas could collect in the closed in space and create an explosion hazard. Hydrogen is lighter than air so it naturally rises through the vent tubing to the outside air. As I understand it hydrogen is released by the batteries during charging/overcharging. Now just how much hydrogen is released is a matter of debate and I'm not qualified to answer that. Before I did my dual battery conversion I researched for a couple days to come up with my setup. I occasionally read about people out there who have gotten away with zero venting, so far. I did not read about anyone who had or knew about an actual explosion. Just because your compartment has holes does not mean it is properly vented. That would depend on where the holes are. If they are in the floor they would do nothing to allow Hydrogen to escape as it will collect at the top.

[chuckster57]

Normally a fifth wheel battery box has a hole in the bottom that extends down past the floor line. If your new box is covering one of those holes, it should be simple to add a fitting to vent it.

[gearhead]

My batteries were essentially unvented until I put them in this box. It's just how lucky do you feel? If all the conditions are right you could get a bang.
I thought about just removing the hose and leaving the little 4 inch vent opening. But no. And I needed a project that day to get me out of the house.

[chuckster57]

Wow, it never ceases to amaze me what some dealers will do or NOT do. I know the factory ships a single group 24 box vented on the bottom and top. Adding the second box is simple, but it sounds like your dealer went for the cheapest route.

[AnolaBob]

Thanks for info gents. My next step was to remove the hose and use the hose vent located at the top of the battery storage area.

I should then get dual vented boxes or add more vents to the area.

[chuckster57]

If your batteries are in a compartment, they need to be vented from the floor line to a vent on the exterior of the trailer. If they are on a tongue then the boxes are self venting.

[gearhead]

Wow, it never ceases to amaze me what some dealers will do or NOT do. I know the factory ships a single group 24 box vented on the bottom and top. Adding the second box is simple, but it sounds like your dealer went for the cheapest route.
That's giving them too much credit. They go for incompetence mostly.
If you've never experienced one of these mega dealers and their lack of organization, you have truly missed a masochistic experience.
YES, beat me up some more, I paid extra for it. YES, you can keep it 6 weeks for a 2 day job. YES, I'll clean up the dirty handprints you left.
LOL

[Lawdog]

This will be one of the first mods I do on mine. I will post pics when I do. In my 28RDB, the factory battery sits in a side compartment big enough for only one battery. So I will put the dual box in the front and run the vent pipe from there back to factory hole on that side.

Question: what is the reason for needing a vent on the bottom? My Century Plastics box is solid on bottom. How important?

[larry337]

My factory box was also completely sealed. I don't think you want a vent on the bottom. Hydrogen has rises because it's lighter than air.

Sent from my SM-G920V using Tapatalk

[chuckster57]

If the box is in a sealed compartment, there isn't proper air exchange. As the gases rise there needs to be fresh air to replace it.

I have yet to see a battery box in a sealed compartment from the factory NOT have the vent hole on the bottom and top.

[larry337]

If the box is in a sealed compartment, there isn't proper air exchange. As the gases rise there needs to be fresh air to replace it.

I have yet to see a battery box in a sealed compartment from the factory NOT have the vent hole on the bottom and top.
I stand corrected, I kept my factory box so I went out and looked at it and sure enough there is a hole on the bottom.

Sent from my SM-G920V using Tapatalk

[JRTJH]

There are several things to consider when buying an "approved" battery box for an RV.

First: An "approved RV battery box" may be something as simple as the one you find at WalMart in the automotive section. If you're going to install a battery on the tongue of a travel trailer (RV) then it's probably an "approved box". HOWEVER, if you're going to install it inside the RV, in a compartment, that kind isn't approved for use.

Second: All lead/acid batteries produce hydrogen gas when charging. Hydrogen is explosive and is lighter than air (will rise). If you think about the front compartment of most fifth wheels, there is an "exposed electric motor" at the top of the compartment. It operates the front landing gear. Any "lighter than air explosive" would accumulate around that motor. Hit the switch after parking for the night and if there's any large accumulation of hydrogen... "BOOM". Will it happen? maybe not... Could it happen? Yes, definitely it can. Is it worth the risk? Only you can decide that answer.

Third: Battery boxes "approved" for "enclosed compartment use" in RV's are vented top and bottom. This provides for air flow to allow the "convection current" necessary for evacuation of the box (think wood burning fireplace chimney). Without the convection, the hydrogen gasses would continue to be produced, cause pressure inside the box and possibly escape through any small leaks in the box. This could allow hydrogen to escape the box, flow into the closed compartment and accumulate there.

Fourth: In "normal charging" there is very little hydrogen gas produced. That is not the big danger. We've all read about the WFCO converter/charger that "stuck in high charge" or otherwise failed. The vented battery box is intended to protect the RV from accumulated hydrogen in those types of situations. When and how much "warning" do we get about a malfunction in the charging system? The vents are the "safety link" in that situation just as a circuit breaker is the "safety link" in electrical systems.

Fifth: Keystone ships all fifth wheels with enclosed battery compartment with a battery box vented "top and bottom" with both venting to the outside. On the Cougar XLite series, the battery compartment on the curb side, front of the RV is completely open on bottom and is vented out the front of the RV through a 2" hose on top of the battery box. There is still the "double vented battery box" even with this type of compartment.

Many dealers will "just add another box from WalMart" if you insist on a "dual battery setup". If they do that, they aren't doing you any favors and are setting you up for a possible dangerous situation.

Any battery box used in an enclosed area should be installed with two vents, one on top and one on bottom to provide for proper ventilation to the outside.

Don't confuse "RV APPROVED" with "FIFTH WHEEL APPROVED" when considering battery boxes. One is intended for use "in the open on an RV tongue" and that kind isn't intended for use with batteries "stored in an enclosed compartment" as is typically the situation on a fifth wheel.

They are "two different animals" !!!

[Lawdog]

Great info. Thanks!