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Securing Battery Box

Brian_Burk

New Member
How does everyone secure their batteries? I have three (3) 12V AGM Group 31s located in the forward part of the quarter berth by the nav station and will be adding a 4th shortly. The existing ones are kept in individual plastic battery boxes and secured with straps tied to eyelets screwed into the bottom of this compartment. As far as I can tell, the eyelets are screwed directly into the hull. I am not familiar with the structure at this location, but do I run any risk adding another set of eyelets in the same general location? The screws are very short, but I keep picturing the worst case scenario with the screws piercing the hull! I doubt that is the case given this is a common place for the house batteries to be kept. Any input is appreciated!
 
Look closely at the floor of the space. Most of it is flat, and that is not the hull, but a plywood floor. With 4 batteries, one will be on a curved part. In that case it will be directly on the hull.

I used straps, but not the ones sold for the purpose, because the were plastic and no way would hold heavy battery. I bought straps that were intended for a fuel tank, which had stainless hardware instead of plastic.

A better solution if you are up to the work would be to cut the top of the berth and build a box to fit, but I think few people go through that effort.
 
Don't screw anything in to the hull. If the cored part, it will allow water intrusion. If the uncored part, it is not very thick except at the centerline. My batteries are under my quarter berth. Four 6 volts and one 12 volt Group 27 as starting battery. The floor of the locker is wood. I built a platform above the floor, epoxied and screwed in for the starting batt, and that allowed me to install straps to hold it down. For the four 6 volts, they are held from moving with stainless uprights screwed to the floor. Then to prevent them from coming out in a knockdown, I have locker doors in the flat of the 1/4 berth. Those are hinged on one side and held down on the other side with stainless sliding brackets. Finally, to make sure the batteries can't move, the top locker doors have pieces of wood attached to the underside. The wood pieces were sized so they just touch the top of the batteries when the doors are closed. All this holds the batteries from moving laterally or up in case of accident. The only hard part was to make sure the wood on the locker lids was located so it did not interfere with all the cables running across the batteries. In a knockdown, you don't want 300 pounds of batteries flying around. If I remember, I will try to take some photos.
 
Don't screw anything in to the hull. If the cored part, it will allow water intrusion. If the uncored part, it is not very thick except at the centerline. My batteries are under my quarter berth. Four 6 volts and one 12 volt Group 27 as starting battery. The floor of the locker is wood. I built a platform above the floor, epoxied and screwed in for the starting batt, and that allowed me to install straps to hold it down. For the four 6 volts, they are held from moving with stainless uprights screwed to the floor. Then to prevent them from coming out in a knockdown, I have locker doors in the flat of the 1/4 berth. Those are hinged on one side and held down on the other side with stainless sliding brackets. Finally, to make sure the batteries can't move, the top locker doors have pieces of wood attached to the underside. The wood pieces were sized so they just touch the top of the batteries when the doors are closed. All this holds the batteries from moving laterally or up in case of accident. The only hard part was to make sure the wood on the locker lids was located so it did not interfere with all the cables running across the batteries. In a knockdown, you don't want 300 pounds of batteries flying around. If I remember, I will try to take some photos.
Yes please post some photos.

Thanks
 
I don't know if this photo shows how the batteries are secured in the locker very well. I'll try to explain. This shows 4 Lifeline group 27 AGM batteries in the forward end of the Quarter berth. The plywood top around the opening of the locker overhangs the sides of the locker by about 1". When the four batteries are placed in the locker, they are then spread out so that they are all under the overhangs. This creates space between the batteries both fore and aft and athwart ships. Those space are then filled with pieces of wood which are cut just wide enough to fill the spaces. The wood blocks are then screwed into place to the plywood floor of the locker. The batteries are now trapped in the locker and can't be removed until the wood blocks are unscrewed and removed. I hope this makes sense.

Jim
 

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I screwed 2x4 blocks that rest on top of the batteries to the top of the access panel. The access panel is restrained by barrel bolts.
 
My method in photos. Four 6 volt batteries and one Group 27 12 volt starting battery. First shows an example of the L Brackets my machinist fabricated to hold the batteries from sliding around. Screwed to battery box floor. (The six volts are wedged in so they do not all have these brackets around them.Second photo shows the six volts. The farthest aft is strapped down with a black strap. Third is photo of locker tops closed. Fourth shows the 6 volt locker top, with wood supports to hold the batteries. Last is the outboard locker, holding starting battery, which is strapped down and held in place as well with L brackets, along with negative terminals and my relays to combine the batteries when charging.IMG_20210414_112445301.jpgIMG_20210412_145506861(1).jpgIMG_20210412_144641514.jpgIMG_20210412_145458984.jpgIMG_20210412_145254175.jpg IMG_20210412_145506861(1).jpgIMG_20210414_112445301.jpgIMG_20210412_145506861(1).jpgIMG_20210412_144641514.jpgIMG_20210412_145458984.jpgIMG_20210412_145254175.jpgIMG_20210414_112445301.jpgIMG_20210412_145506861(1).jpgIMG_20210412_144641514.jpgIMG_20210412_145458984.jpgIMG_20210412_145254175.jpgIMG_20210414_112445301.jpgIMG_20210412_145506861(1).jpgIMG_20210412_144641514.jpgIMG_20210412_145458984.jpgIMG_20210412_145254175.jpg
 
@jimcleary and @terry_thatcher - Once again you've provided me great insights into my next project. Question for you - do you have anything other than the plywood floor under the batteries? I have a house bank of 4 6v batteries but my space is currently made much smaller by the fact that I have a plastic battery box for each battery. They barely fit in there AND I need to add a starter battery to the space.
 
You really need to have the batteries in an acid proof if they are the flooded type. You can mount AGM without a box. I was not able to fit 4 6V batteries in there-part of why I went to Lithium. More battery in less space. I have 300Ah of Lithium (equiv to 600Ah of FLA) in a little more space than 2 group 31s.
 
I do not have battery boxes. I guess there’s some risk there, especially if we capsize. I have epoxied the floor. To deal with small leaks. I do not have the skill level to do what Warren did and move to Lithium and I don’t want to change my charging system right now,
 
I do not have battery boxes. I guess there’s some risk there, especially if we capsize. I have epoxied the floor. To deal with small leaks. I do not have the skill level to do what Warren did and move to Lithium and I don’t want to change my charging system right now,
If your insurance depends on a survey, a good surveyor will not pass a boat with FLA batteries that are not in boxes. ABYC requires it.
 
Thanks for the replies. Looking into a battery 'tray' that can hold multiple batteries. Since I don't need anything fully enclosed I imagine it would suffice.
 
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