battery explosion risk?

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mikeylikesit

mikeylikesit

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so related to my inverter install thread......

I have to put the batteries inside the coach. If I use the T-105 flooded cell batteries, I'll have to ventilate the compartment to the exterior and seal up the space "airtight" so the gas doesn't get into the interior living space.  While this is doable, I'm wondering if I were to use a AGM or gel type battery, would this be necessary?  I understand the added expense of using a gel or AGM.

specific question is, since I have never used either;  do the AGM or gel type batteries emit HS gas?

thanks!
 
AGM batteries don't need to be vented and they will only expel gas if they are overcharged which is hard to do with a modern converter.
 
Go with the AGMs. At one point I looked in to putting flooded batteries in a sealed basement compartment, and proper venting is more complicated that simply cutting a hole and attaching a vent pipe. To ensure proper circulation you really need two vent lines, an "in" and an "out". Battery gasses are heavier than air so the "out" vent line must be from the bottom of the battery enclosure and must run downward - if there is an upward portion of the vent line it could stop proper outward flow. After some research I decided the only way I could be certain I was getting proper ventilation would be to install a ventilation fan to force air circulation. I then considered that there would be no way for me to know if the fan quit running. The project rapidly escalated from that point. And finally, there's the servicing of the flooded batteries. I'm sure it can be done but I abandoned the project.

Go with AGMs.
 
My Miata has the battery in the trunk, and has an  AGM battery required.  It DOES require venting, but it has a vent tube on the battery to be connected to a 1/8 inch or so tube, run down and outside the trunk.  Even with this, they can still explode.  Mine did.  I assume the water level in the sealed cell battery got low, and when I hit the starter... BOOM!!!.  The battery was 84 months into a 72 month warranty.  Everything was contained inside the battery compartment, so no other damage.

Bottom line:  AGM do need vented, but it is a simple job.  Still, keep them in an enclosed (no need to seal) area.
 
Well, shoot.  If I have to ventilate the compartment, I might as well go with conventional wet cells.

It shouldn't be too difficult, and the cost savings for batteries is pretty attractive. (less than 50% of AGM)
 
I had a 1991 Miata with the battery in the trunk. It had a vent hose connected to it that ran outside.

I've recently bought a couple 12 volt car AGM batteries and they have a oblong vent on each side of the top of the battery for a vent hose to be added.

I replaced my Miata batteries twice and was not impressed with the battery being in the trunk, think they got overheated here in the central valley of California.
 
Gas explosions of AGM batteries are very rare, rare enough that the fire safety code does not require venting for them. Obviously anything can fail, as the examples above show.  Many cars have AGM batteries in sealed compartments these days, so it sounds as though the Miata has a design problem of some sort. A combination of high heat and excessive charging can damage any battery.    Even Lithium-Ion types (just ask Samsung!).


Flooded cell batteries, including the so-called maintenance-free types, are designed to continuously vent hydrogen gas in normal use. Valve-regulated (VRLA) AGMs are designed to release hydrogen gas only in severe failure mode. Big Difference. AGM batteries won't out-gas unless internal pressure builds to the point where an explosion is likely.  But releasing the hydrogen gas is itself an explosion risk, so at that point it's like bargaining with the devil.
 
My Miata is an '01.  The explosion was indeed a rare occurrence. Venting is VERY SIMPLE.  I requires a vent tube the size of a drinking straw through the floor.
 
mikeylikesit said:

Well, shoot.  If I have to ventilate the compartment, I might as well go with conventional wet cells.

It shouldn't be too difficult, and the cost savings for batteries is pretty attractive. (less than 50% of AGM)
Click to expand...

I've had FLA's in the storage compartments of three different trailers over more than 10 years. Never had a problem.  In all cases, however, I have left the outside hatch blocked open anytime I was charging them or using them heavily. 

FLA battery explosions can and do happen. In most cases it is the very confined space between the level of water in the battery, and the top of the battery that is the issue. Please note that this area of concern is totally confined within the battery case itself.  Concentrations of hydrogen gas can get quite high there.  However, in a several cubic foot storage compartment, getting that kind of concentration of hydrogen gas would be extremely difficult to achieve. Even if you electrolyzed all of the water, you just can't generate that much hydrogen gas. And even if you could, most of it would leak away because it is so light.

[font=verdana, arial, helvetica, sans-serif]There is an issue of Mythbusters where they try to generate an explosive mixture of natural gas. It was very difficult to achieve. :)[/font]
 
Even if the water in the battery is broken down into Brown's gas (THe perfect ratio of oxygen and hydrogen) you still need a spark or other heat/flame source. Now this can happen when the plates run dry but routine and proper maintenance prevents this.

Generally the explosion is from steam (Boiling water) and is more a POP than a BOOM.
 
I'm a new RV'er but have a few decades of battery experience.  I have used tons (literally) of T105's and never once have I had one even "pop" much less explode.  It actually takes a concerted effort to get a battery to gas enough and contain that gas, then have a trigger for anything bad to actually happen.

However, you do want to vent them due to the smell and acid vapor they inevitably expel.  While you typically don't charge them hard or long enough for serious outgassing, in a confined space you'll get the rotten egg smell and anything within the vicinity of the battery will be subjected to the vapor and inevitably corrode or be damaged.  So you want them somewhere that's isolated from living space, and with some way outside air can get to it.  A 1" hole with screen on it for critters easily covers fumes and hydrogen venting for a couple house batteries.

Mark B.
Albuquerque, NM
 
so, I'm a bit behind on this project due to a partially broken foot.  :p ::)  *note to self - never wear flip flops in a high performance off road vehicle.*

anyway, finally getting around better, and have all the components acquired and the necessary access opened up.......going to get out there later today and get some pictures of the "before".

I went with a  Tripp Lite APS2424 Inverter / Charger 2400W  and 2 WindyNation 100 amp-hour 100AH 12V 12 Volt AGM Deep Cycle Sealed Lead Acid Battery. I went ahead with the AGM's for the reasons Mark stated in the previous post to this......corrosion, smell, and potential hazard.
This should provide plenty of capacity for the DW to watch TV all night, as well as charge a cell phone or tablet.  (I hope, or I'll be adding more)

I'll be bringing a 30a circuit down out of the breaker panel to feed the inverter, and using to inverter to feed a small 4 breaker box, where I will connect the intercepted convenience outlet circuits.  Unfortunately, the refrigerator is connected to one of these circuits.....so I'm waiting to assess whether or not I'll need to change that. (I'm an electrician, so I can do it, I just didn't want to get into that unless necessary).  Plus, the fridge works alot better on 120v than on propane.

The best part of this scheme is that I won't have to impact any of the storage, as it will all fit in the dead space behind the drawers under the dinette benches.
 
>AGM Deep Cycle Sealed Lead Acid Battery<


Yes, that is the best way.  They are made for that sort of application.


A couple of batteries will be fine for a couple of days.  If you plan on being away from power for longer, you may want to consider adding some solar.  I find that solar does a better job of bringing lead-acid batteries back to a full charge than a generator does.  The absorption stage just plain takes a lot of time, and I hate to leave a generator going for hours for just a few amps of charging power.  Bringing lead-acid batteries back to 100% regularly prolongs their life.
 
Back2PA said:
Battery gasses are heavier than air so the "out" vent line must be from the bottom of the battery enclosure and must run downward - if there is an upward portion of the vent line it could stop proper outward flow.
Click to expand...

Actually, that's backwards.  The explosive component of battery outgassing is hydrogen gas, which is lighter than air.  So the vent line has to slope upwards from the TOP of the compartment to free air to avoid trapping pockets of hydrogen gas.

Propane vapor is heavier than air which is why you'll find vents at the bottom of a propane compartment or no floor at all there.
 
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