Eve cells 280 304 are not really suitable for offshore sailing boats

[CaptainRivet]

Wow very good research...irony off
What about the overpressure valves of the cells when they get overcharged in a closed sealed box...congratulations you build a bomb
And a battery box for your cells shouldn't be made out of wood (still hundreds of youtube videos show this wrong) or aluminium but flame retarded and isolating material like eg nylon boards. If wood gets wet it gets conductive...and wood well can burn very easily in a short.
My BMS is installed in an ip67 rated installation box incl rubber cable gaskets so prevented as good as possible from moisture and saltey corrosive environment.

The good thing is if you have the bank (doesn't matter if DIY cells or drop in) in a waterproof area and the area get flooded that the submerged cells short you have no battery power but the cooling water cut also the oxigen off around and prevents a fire. The worst is if your lifepo4 gets submerged and then water disappear and the bank is wet and exposed to air while the cells are still alive and shortend...then a fire is most likely to happen (also with AGMs).
That's why my bank is between 2 watertight helper bulkheads and if ownerhull is >90cm full of water that area only then gets floaded and a bilge pump tries to keep the level in there as long as possible low but if that area then gets submerged that bilgepump also shorts and the area between this 2 helper bulkheads keeps been flooded and cool/cut oxygen off the shortend bank till they are totally dead even if the rest of the hull the water disappears.

[Fuss]

That’s all correct, my cells are in a waterproof plastic box but on the top is a wood lid. This is a big improvement on the self mades that I have seen, most of them would have a big problem in a water under the sole situation.
Mine has fans inside. It’s still much better protected than probably 70% of the self built installs out there but still not perfect, that’s the reason for my post…to make self build people aware..,especially when using cells with alu cases with thin plastic protection.

Also , it’s easy to say put them aft, under the bed but I need them in the middle for voltage drop reasons. The whole boat is designed around having them in the middle.
But just in case everyone thinks my boat is faulty and flooding… the lead batteries lasted 16 years before getting replaced with lifepo4.
16 years, that’s right, 16 years of mistreatment …charged until bubbling and screaming sometimes equalised at 32 v… charged at .6c…I never cared about that part, they sometimes got everything I could throw at them.
Show me an AGM that… oh …oh, sorry, getting carried away again….

[Fuss]

I looked at more self builds now, so far I have not seen one 10kwh+ system that could handle half a Liter of water splashed over it without water getting places you would not want. Especially vulnerable are these non enclosed BMS’s. Open circuit boards above the batteries, the enclosed Daly BMS being one of the exceptions. None were built in traditional style battery enclosures and all were installed at low points.

Just in case you think these self builds are all perfectly water protected as many on here would have you believe.
The drop ins in this regard seem to have an advantage.

[rslifkin]

Originally Posted by Fuss

I looked at more self builds now, so far I have not seen one 10kwh+ system that could handle half a Liter of water splashed over it without water getting places you would not want. Especially vulnerable are these non enclosed BMS’s. Open circuit boards above the batteries, the enclosed Daly BMS being one of the exceptions. None were built in traditional style battery enclosures and all were installed at low points.

Just in case you think these self builds are all perfectly water protected as many on here would have you believe.
The drop ins in this regard seem to have an advantage.

I think water taking out electrical systems is one of those places where a lot of people are just complacent. They've never had an issue with it, so they just don't worry about it and haven't accounted for it in their construction. Or they put it somewhere higher up in the boat, so the figure it'll never get flooded, but failed to protect it from water coming down from above.

Even with lead-acid batteries I've always had the thought of "do I need to worry about these becoming submerged in a flooding emergency, or is the placement such that I'm already screwed before they go under?"

[CaptainRivet]

Originally Posted by Fuss

I looked at more self builds now, so far I have not seen one 10kwh+ system that could handle half a Liter of water splashed over it without water getting places you would not want. Especially vulnerable are these non enclosed BMS’s. Open circuit boards above the batteries, the enclosed Daly BMS being one of the exceptions. None were built in traditional style battery enclosures and all were installed at low points.

Just in case you think these self builds are all perfectly water protected as many on here would have you believe.
The drop ins in this regard seem to have an advantage.

Very simple, mine is between 2 water tide bulkheads underneath the bed so cannot get any splash unless the owner hull is 80cm under water.
Its on purpose there as a) coolest place on vessel (barefoot route around the world, so heat is an issue) and b)near mid of vessel good for balance away from sugar scoops where original bat location was.
Box is build from pp boards with acrylic cover+seal, also fuses are covered with acrylic board. That will definitely handle even a 5l bucket of water. That compartment has its own bilge pump so even if water gets in it need its to get to about 50cm standing in there till fuses would be shorted. Aim even in a desaster have as long power as possible.

The BMS sits 30cm higher in cupboard in an ip67 onwall outdoor plastic electro installation box with rubber seals for cable going out. Box was 8 Euro in local home depot store, the same the transfer switch for the input of the AC in shorepower or genset or boost inverter of the multi...normally its at boost inverter as i hardly ever plug into shorepower even at marina. A manual switch is simple, cheap and robust for the occasional use.

[CaptainRivet]

Originally Posted by rslifkin

I think water taking out electrical systems is one of those places where a lot of people are just complacent. They've never had an issue with it, so they just don't worry about it and haven't accounted for it in their construction. Or they put it somewhere higher up in the boat, so the figure it'll never get flooded, but failed to protect it from water coming down from above.

Even with lead-acid batteries I've always had the thought of "do I need to worry about these becoming submerged in a flooding emergency, or is the placement such that I'm already screwed before they go under?"

Issue is a lot don't think at all. Lead batteries or original main battery box are often in the engine rooms as not compromised by heat but LFP are. Its convenient, short runs to alternator and starter as well as outside of living area due to gasing. But because LFP are senstive to heat and not gasing you can put them inside living areas and the new location is chosen so they are put as close as possible to old location but outside the engine room to avoid more installation efforts but don't think about water ingress, heat and security. Another thing they are not aware is the massive energy qith ultralow internal resistance thats in an LFP bank compared to lead and eg with lead the high internal resistance limiting the current in a short curcuit...so i don't care if lead gets flooded but lithium i must but a lot have no glue they have to.

And this all has in general nothing to do if you have DIY or drop in LFP batteries. And its eg not a problem at all if the open board BMS is above the cells if its in an air tight battery box . If you think about completely sealing the box, well if the overpressure valve of cell blows that pressure needs to go somewhere and if your box is totally watertide you build a bomb unless you install proper overpressure valves in the box too that allows to release this pressure or the case breaks in a calculated way, not with DIY...how could you test that?
Thats why i build the box watertight but then have the holes for the battery cables as large as the protection cover tubes of the cable but don't seal it. Like this its air and moisture tight so nothing corrodes insight but if pressure valve of cells blows the pressure can leave the box. Simple and cheap method instead installing terminal and need of pressure relief valves...
My box is made from 20mm PP boards which als gives it mechanical stability and protect the cells incase an object breaches the hull and eg could penetrate the bank.

[rslifkin]

Originally Posted by CaptainRivet

Issue is a lot don't think at all. Lead batteries or original main battery box are often in the engine rooms as not compromised by heat but LFP are. Its convenient, short runs to alternator and starter as well as outside of living area due to gasing. But because LFP are senstive to heat and not gasing you can put them inside living areas and the new location is chosen so they are put as close as possible to old location but outside the engine room to avoid more installation efforts but don't think about water ingress, heat and security. Another thing they are not aware is the massive energy qith ultralow internal resistance thats in an LFP bank compared to lead and eg with lead the high internal resistance limiting the current in a short curcuit...so i don't care if lead gets flooded but lithium i must but a lot have no glue they have to.

I agree, many boats have poorly placed batteries. And even lead-acid batteries live a shorter life in hot environments. Starting batteries in the engine room is often a necessity, especially with larger engines where cable runs would become impractical if the batteries get too far from the engines. But they should still be protected from heat as much as practical.

House batteries generally shouldn't be in the engine room (and my current lead ones aren't), but when I go LFP I may end up moving the house batteries into the engine room (in an area that can be kept cool enough) based on available space and for weight distribution purposes (as the current batteries are really too far forward in the boat).