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Rvbuzz · 02-19-2015, 05:01 PM

My RV does not have enough batteries for dry camping. It only had 2 group 31 deep cycles and one tested bad recently so I replaced both of those with 2 costco 6v golf cart batteries.
My battery compartment is under my entry steps and does not have enough room to add 2 additional 6v batteries.
The next compartment back on the same side contains the inverter and is large enough to add the 2 batteries. I have already bought the batteries and 2 6v battery boxes for this install.
I know the compartment will need ventilation and I can put one on the bottom or on the compartment door. May even be able to add a vent to the interior wall of compartment.

I guess I need to know if the gas from batteries is heavier than air or lighter.

My plan is to add a 1/2 " sheet of plywood on the bottom of the metal compartment to spread the weight across the bottom. The batteries will be tied down to the floor with the straps provided with the battery boxes.

Any thoughts Or concerns?

Thanks

Ray,IN · 02-19-2015, 05:15 PM

Hydrogen is the gas emitted, it is lighter than air.
My chassis and house batteries (lead acid) are in the same closed compartment as my inverter, as designed by Winnebago. This compartment is isolated from the rest of the coach, and only has a small opening at the top of one side that leads to the frame area just below the floor.

vsheetz · 02-19-2015, 06:15 PM

I have the original pair of batteries under the steps, plus a later added pair in another compartment. No special venting.

FleetMan · 02-19-2015, 08:55 PM

Spend some time searching the archives on this forum for a similar request. I remember seeing one where someone did exactly what you are asking about. The article included photos showing the cables connecting the additional batteries and the modifications which were done to the left front storage bay to accommodate everything.

OB-One · 02-19-2015, 09:09 PM

The primary gas produced by lead-acid batteries is hydrogen. Hydrogen is much lighter than air and difficult to contain.

The amount of hydrogen evolved is approximately 0.016 cubic feet per cell, per hour, per amp-hour of charge current at sea level at 77F. A 12 volt system has 6 cells per battery string so that's 0.096 cubic feet of hydrogen per 12 volt string per hour, per amp-hour of charge current.

The LEL, (Lower Explosive Level) of hydrogen is approximately 4% by volume. The preferred maximum concentration of hydrogen is 2% by volume.

Tony Lee · 02-19-2015, 09:32 PM

VERY bad practice to have flooded cell lead acid batteries in the same compartment as sophisticated electronics.

Two main reasons. Possible ignition source in an explosive atmosphere and the highly corrosive vapour that is emitted due to the gas bubbles bursting on the surface of the electrolyte

Bumps · 02-19-2015, 09:39 PM

Our batteries are in separate compartments and ventilated on the top and sides. I think generous ventilation is the key, regardless of whether it comes from top or bottom. \ken

Rvbuzz · 02-19-2015, 10:58 PM

Thank you for your help everyone. I will be sure to provide generous ventilation.

I have an enclosed car trailer with a battery located inside. It is in a battery box with a hose on the top vented to the outside. It looks hokey but that is the way it came.

My plan is to do a much better job than that.

Thanks again.

Doggy Daddy · 02-19-2015, 11:37 PM

If you change your coach to AGM (Absorbed Glass Mats) batteries. You won't have to worry about ventilation of gas. Glass Mats are sealed and don't vent. They can be placed/stored in any position (on side, back or upright).
Deep Cycle Batteries for RVs . You should also consider solar as an investment if you plan to continue a lot of boondocking.

Statgeek · 02-20-2015, 05:08 AM

Agree with Doggie on this. Since you are going through the trouble, consider AGM instead. However, know that they require a different charging profile so it is never good to mix AGM with Wet Cells if being charged by the same charger. One set will be improperly charged and fail sooner than normal. Also verify that that your charger (sometimes charger/inverter combo) has a charging profile that will match the requirements of whatever AGMs you buy (there are different AGM charging profiles).

I switched over to AGMs in my DP and love it. I am not s big boondocker.

MRUSA14 · 02-20-2015, 05:20 AM

X3 on the AGM's. They are soooo worth the difference. I had lots of battery issues on my last coach until I went with AGM's, then I just forgot about the batteries. They went longer, stronger and had no corrosion and zero maintenance required.

Ray,IN · 02-20-2015, 06:00 AM

Quote:

Originally Posted by Ray,IN

Hydrogen is the gas emitted, it is lighter than air.
My chassis and house batteries (lead acid) are in the same closed compartment as my inverter, as designed by Winnebago. This compartment is isolated from the rest of the coach, and only has a small opening at the top of one side that leads to the frame area just below the floor.

I began thinking about what I said, so went to the garage and looked at my compartment. I was wrong, it's got 2 separate sections in that compartment, and upper for the inverter and lower for batteries, which are separated by a rubber/foam seal. Sorry for misleading you.

BatteryPro · 02-20-2015, 05:00 PM

Quote:

Originally Posted by Doggy Daddy

If you change your coach to AGM (Absorbed Glass Mats) batteries. You won't have to worry about ventilation of gas. Glass Mats are sealed and don't vent. ...

Actually AGM are a type of Valve Regulated battery (VRLA) and can expel hydrogen and oxygen gas. The valve is designed to vent in case internal pressure exceeds the valve rating (about 2PSI). This can happen if the battery is held at a high voltage after it is full.

Once the sulfuric acid is fully recombined into the electrolyte, the voltage must be reduced to prevent heating. That is why it is important to use a multistage charger that is programmable for the type of AGM battery and is temperature compensated. Holding a high voltage on a VRLA battery causes heat and can rapidly build pressure. When the vents open, moisture is permanently lost and cycle life is reduced. Severe over voltage can lead to thermal runaway which can cause a fire.

That said, I love AGM technology and recommend it [moderator edit]. it is what I used for 8.5 years until I installed Lithium Ion batteries.

Larry

chboone · 02-21-2015, 12:34 AM

At the bottom of the link to Lifeline AGM batteries there is a note to "Never install batteries in an unventilated compartment or a sealed compartment or sealed container".
I believe the reason for that statement is from this on their web site.
"Lifeline provides safety even during severe overcharging as the batteries produce less than 2% hydrogen gas by volume (4.1% is required for flammability in air)."

Lifeline Batteries - Marine & RV Deep Cycle Batteries