Battery Installation / Fuel tanks

Hi,

Reading most regulations for battery installations, they say that batteries may not be installed directly above or below fuel tanks. I'm a little unclear in the interpretation of "directly" and was wondering if any board members could add some of their own interpretations.

An example that is unclear to me would be an integral diesel tank in a metal hull - assuming this is under a floor board could batteries be installed above the floor ?

In this case does directly mean in the same vertical plane, or some vertical separation is required ?

Thoughts ?
Mark

 

ABYC July 2009
E10 10.7.5 Batteries shall not be installed directly above or below a fuel tank, fuel filter, or fitting in a fuel line without an intervening sole, floor or deck.

 

The author(s) of ABYC E10 10.7.5 probably did not have an integral diesel tank in mind.

But a small design fault in a charging regulator can have unexpected results:
http://www.boatdesign.net/forums/el...battery-53162.html?highlight=exploded battery

 

ABYC's battery section does not state why the battery must be separated by an interface. But to hazard a guess, if the battery was a above and there was acid leakage, this could impact the integrity of the tank over time.
Whether the tank was integral or mounted, the exposure would be the same.


If the battery was below a tank, they discuss that any line, (electrical included) needs to be unaffected by corrosive fumes.

 

I sat on the ABYC committee back when they wrote those requirements. Barry's interpretation is right. The concern is about damage to the tank either by dripping acid or corrosive fumes venting from the battery. However, if there is an deck between the two then it is in compliance and meeting the purpose of the standard. The top of an integral tank would probably not be considered a deck since it is an integral part of the tank.

 

Hi,

Thanks for the responses. I'm pretty clear on the intent of the applicable regulations (leaks / gasses). It just seems to vague and open to interpretation. Having something like "batteries must be installed in a manner to prevent acid spills onto or corrosive fumes surrounding a fuel tank" makes things a bit clearer to me.

In my particular case I've got a great spot for batteries , but it is over an integral tank. I was planning on installing them in leak proof / vented boxes bolted to structure above this tank, but this technically seems like a no go as the standards are written. Could one consider a box a "sole" or "deck" ?

Cheers,
Mark

 

http://ccga-pacific.org/files/library/TP1332-E-FINAL-v2.pdf

Perhaps in Canada the requirements are a little different as I could not find mention of the restriction of installing a battery over fuel tanks. An electrolyte spill containment device is mentioned at 40 degrees of heel. Perhaps I have missed something here

 

Hi Barry,

It's good to see that some of the regulations are being updated - I also noticed allowing non venting batteries in accommodation spaces.

Unfortunately we don't fall into this category with our boat, we are trying to follow https://www.tc.gc.ca/eng/marinesafety/tp-tp13313-menu-143.htm as a basis for design / equipment installation.

It seems like many points are similar to the AYBC standards, but I'm guessing it's update cycle is a much longer period.

Cheers,
Mark

 

ABYC requires venting overboard of battery boxes, etc even with gel, agm etc
I have had 3 specific situations where non-vented or AGM battery cells, shorted, overheated and emitted gas into the boat. Not sure what the gas would be, H2S? is deadly but it was pungent and took a persons breath away. Of course hydrogen might be produced in an over charged shorted battery as well and equipment in an accommodation area would not be spark protected

I would vent all batteries overboard but would never have any battery in the accommodation area

 

One thing that leaves me scratching my head is that they say no to accommodation spaces and suggest not in machinery space... that doesn't leave much in my mind

 

You are looking at a 2004 edition of TP 1332. You can see the current standard at http://www.tc.gc.ca/eng/marinesafety/tp-tp1332-menu-521.htm The Canadian standards were developed directly from ABYC but there are some significant differences. So read carefully.

As for the ABYC requiring venting of all batteries. Lead acid, AGM, Gel cell batteries are all capable of venting. AGM and Gel Cells are Valve Regulated Sealed batteries. The valve is the important word in there. If the battery is overheated (usually by overcharging) they will vent through the valve. Under normal conditions the valve stays closed and they don't vent. But there have been some significant accidents caused by venting AGM or Gel batteries that were in accommodation spaces, where typically there are many ignition sources. So the USCG and ABYC require them to be vented to the atmosphere. That's hard to do in an accommodation space. The good news is that hydrogen disperses extremely rapidly through whatever hole there is above the battery so it doesn't take much of a hole to vent them.