Battery Bank Where?

[Delancey]

Just curious to know where people have found the best location for a house battery bank to be? Maybe 400 amp hrs worth on a 40 foot monohull. What works and what doesn't and why.

Cheers

[Cool Hand Luke]

In the aft cabins under the mattress would be my guess.

[Delancey]

Maybe for some. In my case that space is taken up by my water tanks.

[TeddyDiver]

Down in the bilge. 35' semi long keel so got plenty of room 1100*300*800mm (l*w*h). Battery box is molded as a part of an integrated watertank. That's the plan anyway..

[Mirage35]

Keep balance in mind if the bank gets big enough. Was on a 33' boat this summer with an oversized house bank all on one side - had a visible heel while at the dock.

[hellosailor]

Depends on what corners you want to cut. Ideally, at the base of the mast, to keep the mass near the boat's center of mass. Of course that's under foot. Or in the bilge to keep the weight low, except wet lead acid batteries give off chlorine gas and eat out your lungs and such if they get submerged with sea water, so they are best kept above the water line. Even the "we;re taking on water" waterline. And they emit explosive hydrogen gas during charging, so you might want a proper sealed battery box that is vented overboard, something else to trip over. Which leaves you to find a convenient spot, that won't require long cable runs, won't get tripped over, and compromises on everything else. Including access to check and water them.

[Tayana42]

Delancy, you already know about balance and weight and you know more about how your boat is currently configured than any of us do. Where were the batteries originally located and what options are you considering for battery placement?

[smac999]

don't put batteries in the bilge. if the boat floods up to the floor boards you don't want them underwater. you want them powering the bilge pumps.

under salon seats is a common place. under beds. aft laz. totally depends on boat.

[UNCIVILIZED]

Think short cable runs. Battery cable is pricey, & the longer the run, the less efficient the charging.

[chris95040]

Originally Posted by UNCIVILIZED

Think short cable runs. Battery cable is pricey, & the longer the run, the less efficient the charging.

Good point.

But its such an overconstrained problem. Spending some dough and some time putting in giant copper cable to get your battery someplace thats above the waterline and well situated from a weight perspective could be time and money well spent...

(My 400ah of house bank in a 40ft mono is in the vberth. Two batteries each as far aft as possible under each bunk. Previous owner must have spent some bucks on the cable, its massive.)

[TeddyDiver]

Originally Posted by smac999

don't put batteries in the bilge. if the boat floods up to the floor boards you don't want them underwater. you want them powering the bilge pumps.

under salon seats is a common place. under beds. aft laz. totally depends on boat.

Agree, they are a hazard if unprotected in the bilge. But placed in a proper separately ventilated battery box (as they should) not so...

BR Teddy

[chris95040]

Originally Posted by TeddyDiver

Agree, they are a hazard if unprotected in the bilge. But placed in a proper separately ventilated battery box (as they should) not so...

BR Teddy

With the wiring running into it, how are you sealing it such that it won't just slowly fill with water in an oh-s@&t scenario?

And it must have some sort of lid to access the batteries, so its hard for me to see how this winds up any better than just having them out on their own in the bilge..

[TeddyDiver]

Originally Posted by chris95040

With the wiring running into it, how are you sealing it such that it won't just slowly fill with water in an oh-s@&t scenario?

And it must have some sort of lid to access the batteries, so its hard for me to see how this winds up any better than just having them out on their own in the bilge..

Same as other wiring and piping, run higher above the cabin sole when not sealed through bulkheads. Battery box lid is a part of flooring. Water tight bulkheds in the bilge between sterntube / engine compartment / battery box / anchor rode locker / composting compartment plus two water tanks. Two of these, engine compartment and battery box, have easy access from above (not totally water tight) below the waterline but cabin bulkheads have sils well above the waterline to separate them.
Just few details quite easy to accomplish with one-off design but mostly omitted in standard production boats.

BR Teddy

[Salty Mike]

Charley Morgan put mine in the engine room just inside the door for easy access, he's a smart feller he is.

[Delancey]

I currently have two group 27s in my engine compartment. Working with a limited budget right now and might not go all out for the 400 amp hr bank up front but whatever I do I would like to have the option to expand down the road.

Combining the two group 27s as a house bank and adding another starter battery somewhere would meet my immediate needs and allow me to put off dealing with this until another day.

I do have some real estate beneath the cockpit aft of the engine where a water heater used to be that I have been saving to a special occasion.

Putting the house bank there would give me the shortest run and I think the boat would accept the weight there just fine. Down side is that it is a little tight to access.

Alternately, beneath the settees could be an option. Would be a lot of cable but easy access. Anyone split their house bank like this between two locations port and starboard?