Battery ventilation

[mlydon]

Like many of us I’m sure, my boat has its battery bank under the settee....

In my case, 2 8d’s and the starting battery in the aft half of the compartment, then chargers (ac and solar) plus various breakers in the front half, separated by a non-airtight divider between them. The compartments are essentially sealed off from the rest of the boat by settee cushions - textbook case of what you’re NOT supposed to do for an install, right?

While the boat has survived this way for 50 years so far, this state of affairs just nags at me. I was thinking to install a computer fan forcing air into the inverter compartment, which would spill over into the battery compartment, and installing a grill in the aft wall of the compartment, which would end up dumping the air under the head’s sink, which has Louvered doors, so the gas could escape.

The only problem I see with this is that the head is a fresh water flush, with the solenoid (and head motor) likely not ignition protected ( could spark )

I could put an exit Louvre into the face of the settee base, but that is Mohogany you panelling, and anything I put in would detract looks-wise.

I could reverse the flow, forcing battery gas into the inverter compartment and through to a closet, but again, the inverter or ac unit in the closet could be another source of sparks.

In all cases, I understand that equalising will generate a lot of gassing, and it’s bad for upholstery, etc.
Running ducting from the compartment to a stern cowl vent wouldn’t be practical at 30ft or so

What the heck do people do, and what would you suggest?

Matt

[gamayun]

This had bothered me, too. My batteries are under the nav station, which was a difficult spot to service them. They were also near my sleeping berth so I converted to AGMs. They could still release gases in an over-charge situation, so the area is vented with a small louver panel, but apparently it wouldn't take much in a release to mix with ambient air. It just can't be air tight.

[john61ct]

I sleep over or near bubbling FLA without a problem.

The key is general ventilation of the living space, and not closing the bank in, the fumes are only dangerous when allowed to get concentrated.

Others are more sensitive, or just hate the smell.

Which is when closing them in may become necessary, domino effect then requires controlled "ducting" effect.

Best to ventilate from the living space, taking advantage of the existing negative pressure outbound from / through already-required venting-to-outside, say engine room, cooking vent, head or fridge compressor.