Where Should the Batteries Go ?

[erict]

I'm still in the planning stage of an electrical overhaul and am looking for advice on battery location. This is on a 30' sailboat currently with four 6V batteries plus a 12V starter battery.

The starter battery is underneath the quarter berth (port). One pair of 6V is also under the quarter berth in a separate compartment. The other pair of 6V is jammed under the galley island (starboard). There are no battery boxes and the fit on both 6V banks is so tight it's as if the batts were built in place.

I'm thinking of downsizing the house bank to only a single pair, perhaps Trojan T-105s or SCS200s. With a 60 amp alternator on a 16HP Yanmar diesel, that seems like a sustainable capacity.

But question remains, where to put them. The lockers are barely tall enough now and I'd really like to add proper battery boxes. My understanding is batts in the same bank should be very close together and battery compartments should be vented outside. That will be difficult unless batts go in the port side lazarette. Problem there is the lazarette opens to the engine compartment and I believe batts need to be isolated from the engine.

Thoughts? Where do you cram the batteries in your boat? Where did you find battery boxes to fit into those tiny lockers? What do you do about ventilation?

[Boracay]

For mine I'd ask the designer before launching into any major work.

My limited correspondence with Dudley Dix when I was evaluating cruising boats suggested that he was fairly concerned with weight distribution. His reply was prompt and helpful.

A description of the design can be found here.

As another starting point I'd suggest looking at how well the boat sits to her lines, and where heavy items might be stored.

[Pete7]

Erict, like you we a similar sized boat and limited space for batteries. Our 2 x 110 ah 12 volt house batteries live in battery boxes behind the engine and gearbox. Under engine we run a blower which directs air across the battery boxes and then onto the engine so temperatures and kept within reason. However we don't have the height available to be able to use 6v batteries so choose 12v FLA Varta's which are a good quality battery. In practice 2 11ah batteries are a big enough bank for holidays and I would only consider adding more if we went cruising longer.

Our battery boxes were part of the orginal boat, strong and have steel plates to clamp the batteries down. Those plastic battery boxes with a cloth tie in the chandlers just don't do it for me, batteries need to be well secured, and not with expanding building foam which I saw on one boat we looked over

Pete

[erict]

Originally Posted by Boracay

My limited correspondence with Dudley Dix when I was evaluating cruising boats suggested that he was fairly concerned with weight distribution. His reply was prompt and helpful.

Boracay, this makes a ton of sense, especially considering how remarkably well balanced the boat is.

Pete7, shaving off that inch+ definitely has me thinking about switching to 12V. With venting from batteries over the engine is there any concern of igniting battery gases? How often and for how long do you run the blower?

[Pete7]

Erict, we run the blower more to try and keep engine space temperatures down rather than the build up of gasses. Some gas must be produced, but nothing like fast charging with a battery charger. The blower runs when the engine is on, manual switch at the moment, but I am thinking about a relay from an engine positive so it start automatically.

These are the batteries we are using at the moment, the height just fitting in the battery boxes but I doubt we could fit the slightly taller Trojan 12v without having a lumpy bed at night and certainly not the T105s.

Varta Hobby 81310 A28 Deep Cycle Battery

Pete

[fishwife]

You mat want to consider AGM sealed batteries. The hydrogen given off is recombined in the cap. They don't leak every where in the event of a knock down, which is another plus.

P.

[Pete7]

I suppose the other advantage of 12v batteries is if one dies then you have lost some capacity but can still continue, how well would the instruments and radio work on a single 6v battery.

Pete

[rebel heart]

For a bank that small I wouldn't worry about venting much. Anecdotal, but battery "explosions" are normally just inside a battery that can't vent properly; it's not like the whole compartment lights up (with a couple of batteries). The exploded batteries I've seen are car batteries. Plenty of "venting", except for the battery itself, since the vents were plugged and the hydrogen couldn't escape.

You can vent the battery compartment to the cabin as well; just cut a small hole. Doesn't need to be a major production.

Just my $0.02.

[gonesail]

venting to interior is ok. usually the height of the 6 volt batteries are the problem. you could always have 2 12 volters. they do make some nice boxes here.

[erict]

At the risk of repeating an oft-asked question...

Are 12V deep cycle batteries truly "deep cycle" like the 6V? I keep reading that with 6V you're pretty much assured of thick plates and that the 12V tend to be relabled automotive batteries.

Fishwife, I have been debating AGMs vs flooded. Do flooded batteries simply spill out acid when tipped? What's the critical angle? Do AGMs need to go inside a battery box? Can they be mounted on their side--and tolerate being upside down in a knockdown?

[rebel heart]

re 12v vs 6v "deep cycle":

Depends on who you ask. Any deep cycle battery should have thicker plates and overall just be a lot larger in amp hour capacity than an equivalent starting or "multi purpose" battery. One reason I like 6v batteries is because the compartment is long and somewhat shallow, so trying to swing a monster sized 12v battery in is physically challenging (impossible?).

6v golf cart batteries are popular because people treat golf carts like crap. They get smacked around, drained, run at crazy angles, bumped, and left out in the weather. Plus they're generally managed by businesses who want high quality. Plus, two six volt batteries are roughly half the weight of a comparable 12v , going back to the "moving it around" issues.

It might sound not so important, but try moving a 150lb 12 volt battery from a dinghy into a boat, then down through a companion way, then into a battery compartment.

[barnakiel]

I have a small boat and the batteries are under the head area of the quarter bunk. I hope one day I find something small enough to put them in our keel sump which is very deep, unfortunately very narrow too.

b

[cal40john]

Sometimes it depends on what you're trying to accomplish. I found all the batteries in the bow, more chain than a racing boat usually carries in the forepeak, and the fuel tank under the cockpit removed to attempt to get a CCA boat a better IOR rating.

John