Battery box inside camper.... things to consider

[Ramdough]

All,

I am designing around an M1083 for an overland camper. The location of the starter batteries (and air tanks) is where I want to install a second fuel tank. Also I need to locate the house batteries somewhere.

I am planning to move the starter batteries and the house batteries to inside the floor of the camper in between the camper frame rails but inside the sealed camper volume. I will have a tray under the batteries in case of leaks. The floor will have hatches that are hinged up and I plan to have a in floor hydronic heating in the hatch. I will also have a drain plug in case I get a water in there.

My plan right now is to use AGM batteries unless LIon are cheap enough when the time comes. Looking at around 800AH total plus starter batteries.

I have seen many camper designs and layouts with the batteries inside and there does not appear to be any significant venting to the outside or any seal to the inside.

I know that batteries can vent hydrogen, so I am curious why some campers are ok venting to he inside.

What concerns should I have and what design features should I include?

Thanks!


Sent from my iPhone using Tapatalk

 

[e60ral]

AGM are sealed and shouldn't vent under normal use

 

[shortbus4x4]

Seal battery box to interior and vent to exterior. Batteries vent other gases besides hydrogen and while not likely H2S from charging batteries could kill you.

 

[Stumpalump]

Fwiw the hydrogen rises so a vent near the top of battery box is best. It does not take much venting. A little goes a long way to stop an explosive concentration from building up.

 

[Trestle]

I've used standard wet batteries inside sealed containers that had dedicated vents to the outside of the vehicle. Those are more prone to leaking than an AGM, and I have had no issues. I have considered adding a computer fan to positively pressurize them, but have not found the need. Also there is the risk the fan could fail which would defeat the entire vent system. So I did not follow the positive pressure option. When I want to water the batteries, I turn off anything charging them for a good 1/2 hour prior to popping the top. Gasses are released from the batteries during charging, so that is a safety precaution I take just because it makes me feel all warm and fuzzy.

Some of the benefits of keeping batteries inside of a conditioned space (relatively conditioned as compared to completely outside of the thermal mass) is that it tends to help their performance/longevity.

I've made boxes in steel, then coating the entire inside with a rubber coating. The vent was only 1" in diameter with 4x golf cart batteries. Sealing the lid was not that easy with that setup. That vehicle was heated and cooked inside with propane, lived in for over a year, and the batteries were heavily charged/discharged daily. No issues whatsoever.

Second go around I used 3/4" plywood. Screwed/glued together, coated the inside with layers of fiberglass, then used a wide gasket on the lid. Much better than the previous attempt. Also 4x golf cart batteries, but upped the vent area to a 2" diameter hole. No open flame in this vehicle for heating or cooking, and not worked as hard.

If I can get away with wet acid batteries, you should have no problem with AGM.

 

[dreadlocks]

AGM batteries are rarely suitable for our uses, stick to good ole lead and just have a box that will catch any spills/leaks.. only need to worry about venting if its an airtight environment, hydrogen is very difficult to contain and will easily escape if there's any way out.. nothing to worry too much about really.

 

[llamalander]

AGM’s can be installed in any position (besides upside down) and in hard to reach places where matainance is difficult. Attached to the frame of a vehicle, they need protection but not containment, if you remember to isolate them if you risk immersion. Insulation is not required as it would be with lithium, as long as your charger can adapt to a low temperature. When none of this applies, a regular wet-cell will do what you need, if any does, AGM’s can be worth the extra cost.

For venting, it’s been said that it is only needed when charging. Propane appliances have their own combustion air requirements, so if you have wet batteries in your camper and open flames, you will need to draw in and vent air anyway, which should mitigate the fairly low risk of making an explosive fuel-air mixture. If you are concerned, shut off your solar charging and vent the living space briefly before you light your stove/heater/cigar. If it was so easy to blow things up with electrically produced hydrogen, many more folks would have figured out how by now.

 

[dreadlocks]

my problem with AGM is they are intolerant of 'abuse' and require very precise charge profiles, for most recreational vehicles abuse is high and getting good charge profiles is expensive.. FLA is far more tolerant to recreational loads and what both AGM and Lead consider heavy abuse Lithium just shrugs off (High charge/discharge rates, sitting at partial charge for extended periods, discharging near completely)

Unless your backed into a corner where an unconventional battery location is required, or your full timing it off the grid with very reliable charge supplies.. I personally would avoid AGM entirely.. I've already lost too much money going down that path.. just end up paying more money for something that craps out sooner.