Battery boxes.

[skipperpete]

I’m working on a boat that has “ Lithium” batteries, no idea what variant but here’s the thing, it’s a big set of cells and there’s no enclosure or battery boxes, they’re bolted down to the bridgedeck cabin sole under a settee with a thick perspex sheet across the top which protects the terminals. This is a first for me, historically all the battery installations I see have a fibreglass or plastic box and a lid, often with a vent hose , all bolted down solidly, is this installation just a bad one or is no battery box now a normal thing? There’s been a lot of discussion about emerging battery chemistry fires , in fact a new battery powered cement truck had a spectacular fire yesterday here in Australia with a jet like blast of flames coming out of what seemed to be the battery pack.... I doubt that a battery box would have been of any use in containing that fire and it seemed like the fire fighters took a long time to subdue the flames but what would a fireproof enclosure or battery box be made of, stainless steel, asbestos? Would the box be sealed and vented to outside of the boat?, totally sealed?

[hjohnson]

Originally Posted by skipperpete

I’m working on a boat that has “ Lithium” batteries, no idea what variant but here’s the thing, it’s a big set of cells and there’s no enclosure or battery boxes, they’re bolted down to the bridgedeck cabin sole under a settee with a thick perspex sheet across the top which protects the terminals. This is a first for me, historically all the battery installations I see have a fibreglass or plastic box and a lid, often with a vent hose , all bolted down solidly, is this installation just a bad one or is no battery box now a normal thing? There’s been a lot of discussion about emerging battery chemistry fires , in fact a new battery powered cement truck had a spectacular fire yesterday here in Australia with a jet like blast of flames coming out of what seemed to be the battery pack.... I doubt that a battery box would have been of any use in containing that fire and it seemed like the fire fighters took a long time to subdue the flames but what would a fireproof enclosure or battery box be made of, stainless steel, asbestos? Would the box be sealed and vented to outside of the boat?, totally sealed?

Sounds like you have a DIY Lithium Iron Phosphate battery. These batteries will not go into thermal runaway and/or catch fire. They also don't need venting as they do not offgas while charging, unlike the lead acid batteries you're used to. The battery fires that are normally of concern com from NMC (Nickel-Maganese-Cobalt) batteries. The NMC cells have twice the energy density of LFP, and are quite capable of going into thermal runaway.

However you do want to mechanically protect LFP batteries, keep them dry, and ensure the system is laid out to avoid accidental shorts (as they can source huge amounts of current).

On my boat, the cell stack (8 230Ah cells in 2p4s configuration) is installed in a plywood box under the aft quarterberth. The cells are in a light compression frame, with plastic spacers between each pair of cells (the aluminum chassis under the shrinkwrap is tied to the positive terminal). The plywood itself is covered in epoxy paint, and the cell stack is sitting on plastic pool decking to ensure no water can collect and keep the bottom of the cells damp. The cell stack is also strapped down with nylon webbing, and the box itself is epoxied to the hull.

Within 6" of my positive terminal, I have a 400A class T fuse, and the wiring is laid out so that there is virtually no way that one could accidentally make a dead short in the system. Ie the unfused portion of the wiring coming off the positive terminal of the battery is too short to touch anything other than the fuse holder.

So yes, if it was me, I would have designed a box around the batteries, but mostly to mechanically protect it from something else happening. I'm expecting that the person who built that was counting on nothing else ever being stored under that settee.

[RaymondR]

Yep, the enclosure is there to exclude as well as include things. Interesting things might happen if a rat crawled in under the sheet of perspex and shorted out hundreds of amp hours of lithium batteries.

[GordMay]

ABYC’s ‘E-13' standard for lithium ion batteries encompasses quite a few chemistries, including: lithium iron phosphate (LiFeP04), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel manganese cobalt oxide (LiNiMnCoO2), lithium nickel cobalt aluminum oxide (LiNiCoAlO2), and lithium titanate (Li4Ti5O12).

The general requirements section, of ‘E-13', acknowledges that lithium batteries don’t have spillable electrolytes, nor do they routinely off-gas. Hence, the electrolyte containment requirements, of ‘E-10', may not apply.

‘E-13' leaves battery location, and restraint, up to the manufacturer’s instructions, with some provisos, including:
* Restraint to prevent any visible battery movement.

Battery Installation” ~ by Steve D’Antonio
➥ https://stevedmarineconsulting.com/b...-installation/

A couple of items, from Battle Born Batteries:
New ABYC E-13 Standards For Lithium Power Systems on Marine Vessels
➥ https://battlebornbatteries.com/new-...arine-vessels/

What Is ABYCE-13 Standards for Lithium on Boats
Video ➥

https://www.youtube.com/watch?v=UEnbkBeIlII