I have a small boat and the main deep cycle battery is located just under a "shelf" like thing near the transom that acts as a cover for the gas tank and battery. On one side, it is completely open (the bow facing side), but its essentially otherwise enclosed. The battery is held in place with a plastic battery tray that is secured to the deck, and the battery is held down with a nylon trap and a buckle clip.

In the past, I've always released the buckle clip, maneuvered the battery out of the tray (there's NOT much room to work with, so its quite a hassle) and out from under the shelf in order to charge it. Now, though, I'm thinking of getting an onboard charger that would have the leads attached to the battery permanently, and when returning home, I would leave the battery in place and just plug the charger into the AC outlet in my garage. I know that ventilation is generally important when charging a battery, but my question is - is it safe for me to leave the battery in its tray under the shelf while charging? Again, one side of the "compartment" the battery is in is completely open, but the "shelf" is directly over top of it (maybe two inches of clearance)..

I love the idea of the onboard charger that I would leave plugged in to charge the battery and then maintain it until next usage, but I don't want to do anything unsafe.

Picture of battery in its compartment

Slightly higher view to show covering

  • 1
    \$\begingroup\$ I'd be more worried about the proximity of the gas tank than the ventilation of the battery itself. \$\endgroup\$
    – user16324
    Apr 18, 2020 at 18:44

1 Answer 1


Without the 50 reputation I can't comment yet.

Yes as the commemnt by Brian Drummond suggested, the ventilation is not your biggest problem. This battery looks capsulated, that means there is 1% chance of gas leakage and the ventilation is only for cooling.

There are boxes designed for this purpose that will keep the battery safe, but if the tank explodes, the battery will be next.

The human factor, of spilling, tripping, touching and other things also is a problem.

The same battery is located in all cars in the same way, there is no danger, except the standard 1%.

The ones who want absolute security just put a gas sensor nearby, you might already have the same type of gas sensor in your room.

Make sure no one spills anything on it.

  • \$\begingroup\$ Thanks for the info! I understand that some gases may be released. The question, though, is really whether the act of pulling the battery out of the position it is in as shown in the pictures is reducing any risk.. If I pull the battery out from under the "shelf" and charge it about 18 inches forward of where it is in the picture (and then put it back when not charging) - is that safer than just charging it where it is? \$\endgroup\$
    – daroo
    Apr 27, 2020 at 11:33
  • \$\begingroup\$ It does not make a difference if the battery is capsulated(can not be opened), but it will be heavy. Its better to put it on a small plate with wheels and just put a brake for the wheels like a wooden barricade to stop them, which is removable. The risk will come from touching the cables, that can be bad. \$\endgroup\$
    – CFCBazar
    Apr 27, 2020 at 11:36
  • \$\begingroup\$ Ok, thanks for the clarification.. I'll look into a solution where I can slide the battery back and forth. \$\endgroup\$
    – daroo
    Apr 27, 2020 at 11:40

Not the answer you're looking for? Browse other questions tagged or ask your own question.