Battery bank located in berth area

[GordMay]

Originally Posted by waterman46

... Hydrogen gas is so light it dissipates "diffuses" very quickly once outside the battery compartment. There is no way you could trap enough hydrogen in concentration sufficient to have an explosion in the general cabin area given the small amount of hydrogen generated from the normal size FLA bank,..

Room temperature hydrogen gas is highly buoyant, and if not confined will rise at several meters per second. It diffuses rapidly in air. The positive buoyancy of hydrogen is a favourable safety effect in unconfined areas, but it can cause a hazardous situation in (partially) confined spaces, where the hydrogen can accumulate. Venting the FLA battery box/compartment is recommended, preferably outside, but even if only to the interior cabin.

There are explosion proof ventilators such as Zephyr Industries Battery Box Ventilator that are very reasonably priced ($85), explosion proof and will turn on when the batteries begin to gas.

[boatpoker]

Originally Posted by GordMay

Room temperature hydrogen gas is highly buoyant, and if not confined will rise at several meters per second. It diffuses rapidly in air. The positive buoyancy of hydrogen is a favourable safety effect in unconfined areas, but it can cause a hazardous situation in (partially) confined spaces, where the hydrogen can accumulate. Venting the FLA battery box/compartment is recommended, preferably outside, but even if only to the interior cabin.

There are explosion proof ventilators such as Zephyr Industries Battery Box Ventilator that are very reasonably priced ($85), explosion proof and will turn on when the batteries begin to gas.

True, hydrogen rate of ascent is very fast at about 45mph but ......
Hydrogen gas forms explosive mixtures with air in concentrations from 4–74% and with chlorine at 5–95%. The explosive reactions may be triggered by spark, heat, or sunlight.

I find the 4% a concern especially trapped in a compartment or battery box and possibly in the same compartment as a bow thruster or battery charger.

[becrux]

Originally Posted by stormalong

I Think you have hydrogen and helium mixed up.

Both are light gases and will have the same effect on your speech.

[john61ct]

Yes, the point is, don't trap it, let it ventilate for safety. 95% will be fine, the remainder then need to devise the more complex seal+vent outdoors solutiin.

[admiralslater]

On our Outremer the batteries are located under the saloon seating . We have never noticed any smell even when our FF batteries were brand new . We where told to expect gassing and we did have a very small amout of electrolyte collect on top of a couple of caps (replaced under warranty) so gass must have been there

[boatpoker]

Originally Posted by admiralslater

On our Outremer the batteries are located under the saloon seating . We have never noticed any smell even when our FF batteries were brand new . We where told to expect gassing and we did have a very small amout of electrolyte collect on top of a couple of caps (replaced under warranty) so gass must have been there

Older batteries with sulphated plates will gas a lot more.
Sometimes in a few very scary seconds ..... ask me how I know

[wingssail]

Originally Posted by Palarran

I'm thinking about relocating my battery bank from the stern of the boat to a spot under floor boards in a forward berth area. Possibly even under the berth itself. I know the batteries gas when charging if lead acid and that would need to be addressed. Is there anything obvious about locating a large house bank in this area?

Our batteries (house and starting) are located under our aft berth, pretty much directly under our pillows, and we've slept over them without noticing any gas smell for 32 years (several sets of batteries, of course).

But batteries can gas, and can blow up. (our neighbor just dragged out onto the dock a 12v battery with the caps and top blown off!).

So a battery temperature sensing device on the charger, a good charger with overcharge protection, and frequent checks of the batteries is important (if three of them are fine but a fourth is shorting out it can gas like crazy). Leave the battery voltage displayed at the nav station and look at it every time you walk by.

Put them where you want to, placement should be based on weight distribution and proximity to the panel, switches and charging sources, not whereever it is convenient to stash them, but treat them with respect and caution.

[Palarran]

Thank's again for the advice. If I was going to get a seperate charger for this new bank, how many amps should it be for a bank with say 500 amp hours.

[Exile]

Originally Posted by GordMay

Room temperature hydrogen gas is highly buoyant, and if not confined will rise at several meters per second. It diffuses rapidly in air. The positive buoyancy of hydrogen is a favourable safety effect in unconfined areas, but it can cause a hazardous situation in (partially) confined spaces, where the hydrogen can accumulate. Venting the FLA battery box/compartment is recommended, preferably outside, but even if only to the interior cabin.

There are explosion proof ventilators such as Zephyr Industries Battery Box Ventilator that are very reasonably priced ($85), explosion proof and will turn on when the batteries begin to gas.

I noticed your link to this ventilator product claimed that "hydrogen will set off a carbon monoxide detector." Could be a good early warning if you have one installed near your battery compartment.

[waterman46]

Properly maintained and monitored batteries do not explode.

[Cadence]

Originally Posted by waterman46

Properly maintained and monitored batteries do not explode.

Probably electrolyte being way down.

[john61ct]

And kept working way past EoL, 70% SoH for me.

500AH FLA, go with 80A - 100, 60A would mean bit slower Bulk / CC stage

[tdgaffney]

no, No, NO.


Boats sail better with weight aft and batteries are very heavy. You'll have enough weight forward with anchor and rode, and in some smaller boats, water tank under the V-berth. Weight forward will encourage the boat to pitch up and down in a seaway - under some (actually reasonable) conditions, you won't make headway. All because of all the weight forward.


My Olson 40 has six batteries, installed just forward of the companion way and under the port and stbd settee (at the most aft seat), three each side. Water tanks are one port and one stbd under the rest of the settee. I stow my anchor gear in the bow when cruising and in the lazarette when racing. It makes a difference.


And, as several have noted, sleeping on top of hydrogen sulfide gas is not really encouraged. Its a good way to end your voyaging.

[tdgaffney]

Again, my Olson 40 has 6 batteries, one is for starting and five for the house. I have an ACR (automatic charging relay - Blue Sea PN 8610) such that any battery charger helps all batteries at the same time, no manual switching required. Working the five house batteries with 470AH down to 50% (as shown in my BMV-702 battery computer) would need 235AH to get back to full charge. Which is 12 hours at the dock with my Pro Mariner ProSport 20 Plus battery charger, or three hours with 80A engine alternator.



That's my configuration and it works well for me. When racing for three days we don't get down to 50%, so back to the dock works. When cruising we use the engine to top up in the morning, an hour or so.

[guyrj33]

Originally Posted by tdgaffney

no, No, NO.
Boats sail better with weight aft and batteries are very heavy. You'll have enough weight forward with anchor and rode, and in some smaller boats, water tank under the V-berth. Weight forward will encourage the boat to pitch up and down in a seaway - under some (actually reasonable) conditions, you won't make headway. All because of all the weight forward.

I just have to respond.
Boats DO NOT sail better with weight aft, they sail better with the weight low and in the center of the boat.

Batteries under the settee and racing crew on the rail both place the weight closer to center than anything in the forepeak.