Water bladder next to Batteries

[brazerbramon]

I just purchased an old sailboat last week and noticed that the previous owner had a large water bladder right next to the batteries in the bilge. This bladder seems to crowd the space provided and puts a lot of pressure on the batteries. This seems like a bad idea to me. Possible bladder failure exposing battering to water, pressure on battery housing, etc. What does everyone think about this? Also, should I have the house batteries in a box in the bilge, to further protect them from water and keep them from shifting?

[hellosailor]

Two issues. The batteries should be in a sealed compartment which is vented overboard. During charging they will normally generate hydrogen gas, which can be explosive. Or hydrogen sulphide, which can be toxic and corrosive. And if any seawater (which is supposed to go into the bilge) gets into the batteries? They'll generate chlorine gas. Also, a sealed box helps contain the acid splatter if a battery is overcharged and explodes. (Something like 10,000 people in the US alone go to an ER with eye injuries after their car batteries explode during jump starting attempts, so yes, this happens.)

Second issue is just that water and batteries don't mix. If nothing else, you want to make sure that if the bladder fails, that water can't ruin your batteries. Fresh water would just dilute the electrolyte and ruin them "gently" but still ruin them. And bladders which are not properly secured and anti-chafe padded, do eventually fail.

It sounds like a convenient place to stow all the heavy things, but some more work on "do it right" is in order. Both the bladder and the batteries should also be secured against roll-over. It is not hard to broach a boat, and at that point anything heavy and unsecured becomes literally a loose cannon.

[brazerbramon]

Originally Posted by hellosailor

Two issues. The batteries should be in a sealed compartment which is vented overboard. During charging they will normally generate hydrogen gas, which can be explosive. Or hydrogen sulphide, which can be toxic and corrosive. And if any seawater (which is supposed to go into the bilge) gets into the batteries? They'll generate chlorine gas. Also, a sealed box helps contain the acid splatter if a battery is overcharged and explodes. (Something like 10,000 people in the US alone go to an ER with eye injuries after their car batteries explode during jump starting attempts, so yes, this happens.)

Second issue is just that water and batteries don't mix. If nothing else, you want to make sure that if the bladder fails, that water can't ruin your batteries. Fresh water would just dilute the electrolyte and ruin them "gently" but still ruin them. And bladders which are not properly secured and anti-chafe padded, do eventually fail.

It sounds like a convenient place to stow all the heavy things, but some more work on "do it right" is in order. Both the bladder and the batteries should also be secured against roll-over. It is not hard to broach a boat, and at that point anything heavy and unsecured becomes literally a loose cannon.

Thanks, hellosailor. I confirmed the hydrogen leak last night as my CO sensor wa going off. Nothing on in the boat except a small fan. I will remove the bladder asap. Thank you for confirming my suspicion of poor choices by the previous owner.

There are batteries in two separate sections of the bilge. To me, it makes more sense to remove the bladder and put all the batteries in this section of the boat, midship, low in the bilge. Then put a bladder that fits in its own area.