Battery Under the Quarter Berth

[Easy]

Hi!
I have a 1970 Grampian 26' sailboat and I want to add a house battery.
I already have a starter battery in a locker in the cockpit but was thinking of adding either a
SeaVolt Dual Purpose Absorbed Glass Mat Agm 12v Battery, Group 24, 79 Ah, 660 Mca, 140 Res for 190$
or
SeaGel® Marine Gel Battery Group U-1, 31 Ah, 12V, 215 CCA, 575 MCA for 150$

difference in price and AH's but I don't think I will need too much juice, however my question is can I put either one of these batteries under my quarter berth inside the cabin?
Should either or both be ventilated or are they safer in the locker in the cockpit?
Thanks in advance for any advice!
Cheers, Michael

[speciald@ocens.]

These batteries don't vent unless overcharged. They should not be a problem in the cabin. I'm sitting over 5 8-D AGM batteries as I type.

[Jim Quibell]

That's where we have our main start battery - in it's own battery box that Grampian built in under the quarter berth. You don't want the battery weight in a stern locker.

Our house battery is located in a secure battery box which is located in the port side locker under the rear bench seat in the cabin. This balances the load nicely.

You can find good quality marine batteries for a heck of a better price than you mention. I wouldn't pay more than $80 for a good quality battery. You don't need gel batteries.

[rebel heart]

I have 4 T105's plus the starter battery sitting under the quarter berth; not a problem.

[Randyonr3]

Originally Posted by Jim Quibell

I wouldn't pay more than $80 for a good quality battery. You don't need gel batteries.

Guess that leaves me out......... we have 10, - 4-Ds (lifeline) at a cost of around $500 each..... A good quality battery is worth its weight.. ours have been in the boat for 9 years now and are still opperating above 90% of the origional design.. we hope to get 20 to 30 years out of them....
And AGMs dont gass of when charged proper.. NO gas off means NO corrosion in the area where stored.. our main bank is under the nav station and we didnt want the gass up in the electronics........

[bstreep]

Unless you just hate life, use AGM (or Gel) batteries in enclosed living areas. Yes, I know lots of folks that put flooded batteries in their living areas - not me. Flooded batteries MUST be well ventilated.

[rebel heart]

Originally Posted by bstreep

Unless you just hate life, use AGM (or Gel) batteries in enclosed living areas. Yes, I know lots of folks that put flooded batteries in their living areas - not me. Flooded batteries MUST be well ventilated.

Flooded batteries have been enclosed in boats literally for several decades at this point. The amount of ventilation even a larger sized sailboat needs is accomplished in most cases without even trying.

[bstreep]

Originally Posted by rebel heart

Flooded batteries have been enclosed in boats literally for several decades at this point. The amount of ventilation even a larger sized sailboat needs is accomplished in most cases without even trying.

Yes they have. And it is against ABYC standards. If you want to recommend to someone that they install wet cell batteries into a living space, that is up to you. Not me. In the rare event they gas off and release explosive quantities of hydrogen gas into a living area... I prefer to say "do as I say, not as I do".

Ours are at the foot of our master berth - and they are vented AND they are AGMs.

[bstreep]

BTW, 1 pint of water gassing out of a battery yields about 150 gallons of hydrogen gas - or about 20 cubic feet. At 4% concentration for explosion, that's 500 cubic feet of air. To get it to the recommended 1% concentration, that's 2000 cubic feet of air. I could be in error here - as my chemistry is a bit old...

In any case, gassing of battery water yields a WHOLE lot more hydrogen gas than most folks think. How many of you have ever put a pint or more of water into a battery?

Edit: DANG IT! I was off by a power of 10 - it makes about 1500 gallons of hydrogen gas... Ugh.

[rebel heart]

I'd be interested to see the ABYC's recommendations, but the only thing I can find in the CFR's is this (33 CFR, Subpart I, Sections CFR 183.420):

(e) A vent system or other means must be provided to permit the discharge from the boat of hydrogen gas released by the battery.

Hydrogen is much lighter than air. I've never heard of an explosion onboard a vessel from a battery (minus warships and large commercial vessels with very different battery capacities / charging systems). The only explosions I've ever even heard of are "in-battery" where the battery itself ruptures, which has nothing to do with the compartment the battery is stored in and is normally simply an over expansion of pressure in general rather than a flammable explosion.

[rebel heart]

There's also this one from 33 CFR as well, but a very basic ventilation system (like a hole with a tube) would more than satisfy this requirement. A lot of quarter berths are open to the cabin or closed by rather flimsy (hardly airtight) doors. We're talking about keeping a rather minuscule amount of a lighter-than-air gas moving around.

(c) Small batteries. Small size battery installations must not be located in poorly-ventilated spaces, such as closets, or in living spaces, such as staterooms.

[bstreep]

Originally Posted by rebel heart

We're talking about keeping a rather minuscule amount of a lighter-than-air gas moving around.

You did see my note about the volume, right? How often have you added a pint of water to a battery? And that battery gave off 1500 GALLONS of hydrogen gas from that pint. That's hardly minuscule!

Yes, it's WAY lighter than air. Yes, it will escape any crack (you can't keep it in a steel cylinder - it leaks between the steel molecules).

Here's a recent incident:

H2Incidents: Hydrogen Explosion in Battery Compartment of Dinner Cruise Boat

[sabray]

It would seem that you would want to build a separate compartment that us ventilated topside. This really is not unusual. MNy many boats Luke swans open 60s etc.... Have battery banks low in the cabin sole. If they aren't completely sealed and vented then they vent to the main salon or elsewhere below which usually is a living space.

[DeepFrz]

http://www.cruisersforum.com/forums/...ent-33757.html

[SabreKai]

Most of the Grampians I've seen had a battery box in the stbd quarter berth, just aft of the companion way steps. It would be under the cockpit seats. Thats where mine was on two different vintages. Cables went out and behind the removable steps over to a bus block, on the back wall of the port side rear seat.


Sabre