Lithium battery container

[Maxhead]

Bit of left field question.

I have purchased a 48v 15kw battery system for my shed. It’s got 15x3.2v lifepo4 cells @ 320ah from memory with a bms and it’s all enclosed in a shell like a powerwall.
It will be connected to a Growatt 5kw hybrid inverter and 6kw of panels.

My concern is this battery catching on fire inside the shed.
I know the risk is small but I won’t have any insurance so I’m looking to put this battery system outside.

Looking for recommendations of how I need to do this.
It will be right next to the shed so I need something fire proof and obviously water proof.
Not too worried if the heat damaged a sheet or two but need to save the shed
The photo gives an idea of size.
My idea was to just do a cheap metal sheet box with fire bricks all around.

Thoughts??

http://www.nissanpatrol.com.au/forums/images/imported/2023/06/30.jpg


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[BillsGU]

Remember the batteries will need ventilation for cooling during summer and also I am not sure of the minimum temperature your batteries can handle. I know that here on VIC/NSW border some battery set up's have been damaged because they froze. Don't know if that applies to your type of batteries but it was -7 in the ACT recently.

[Maxhead]

Remember the batteries will need ventilation for cooling during summer and also I am not sure of the minimum temperature your batteries can handle. I know that here on VIC/NSW border some battery set up's have been damaged because they froze. Don't know if that applies to your type of batteries but it was -7 in the ACT recently.

Yes very good point! Summer can get hot but not too bad but winter can get to extreme temps(-16)so I need to think about some kind of ventilation and also insulation which can be implemented for winter.
I’m pretty sure these batteries don’t charge below zero but not sure that is correct.

Maybe a fireproof box inside the shed to eliminate temp problems [emoji2369]


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[rusty_nail]

Yes very good point! Summer can get hot but not too bad but winter can get to extreme temps(-16)so I need to think about some kind of ventilation and also insulation which can be implemented for winter.
I’m pretty sure these batteries don’t charge below zero but not sure that is correct.

Maybe a fireproof box inside the shed to eliminate temp problems [emoji2369]


Sent from my iPhone using TapatalkIs it possible to build a separate building? Like a small shed from bunnings etc? You could insulate it and add a whirly bird for extraction during summer. Keep a firebreak between your actual shed and the power shed and its gravy?

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[Maxhead]

Is it possible to build a separate building? Like a small shed from bunnings etc? You could insulate it and add a whirly bird for extraction during summer. Keep a firebreak between your actual shed and the power shed and its gravy?

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Yes mate, that was another thought to have a little shed few meters away from the main shed so if it goes up in smoke then who cares but temps might still be a problem. Could also run a little heat matt like in home brew under the battery in winter.
I have to consider power cable length and communication cable between battery and inverter


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[rusty_nail]

Yes mate, that was another thought to have a little shed few meters away from the main shed so if it goes up in smoke then who cares but temps might still be a problem. Could also run a little heat matt like in home brew under the battery in winter.
I have to consider power cable length and communication cable between battery and inverter


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I have a "smart" heat belt for my home brew surely it would be fairly.effective to keeping the batteries warmer. Lining the shed in foam would be pretty effective to keeping it a more consistent temp esp in summer.

Re the cost of cable etc cheaper than insurance/replacing the whole shed right?

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[Maxhead]

I have a "smart" heat belt for my home brew surely it would be fairly.effective to keeping the batteries warmer. Lining the shed in foam would be pretty effective to keeping it a more consistent temp esp in summer.

Re the cost of cable etc cheaper than insurance/replacing the whole shed right?

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Yeah mate, I thought about that fridge panel stuff or foam but that shit would catch on like an inferno unless I’m missing something and there is something that won’t burn.
Heat mat would work I reckon.
Yes you are right cable would only be a few hundred so no issue I suppose


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[Maxhead]

I also think whilst it’s running its generating heat so that should help in winter especially during the night when everything will be running off battery.
I suppose experimenting with the system will determine what I need to do


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[rusty_nail]

Yeah mate, I thought about that fridge panel stuff or foam but that shit would catch on like an inferno unless I’m missing something and there is something that won’t burn.
Heat mat would work I reckon.
Yes you are right cable would only be a few hundred so no issue I suppose


Sent from my iPhone using TapatalkWith limited exceptions like firebrick (high alu concentrated brick) or metal everything has a combustion point right? Foam will catch alight just like any other sort of insulator but it will also do the best job at keeping the battery to a consistent state helping keep from any failures due to temperature stresses?

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[Maxhead]

With limited exceptions like firebrick (high alu concentrated brick) or metal everything has a combustion point right? Foam will catch alight just like any other sort of insulator but it will also do the best job at keeping the battery to a consistent state helping keep from any failures due to temperature stresses?

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Yes sorry I’m with ya now! I’m overthinking the idea.
Small insulated shed and temperature controlled heat matt just be work spot on.


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[rusty_nail]

Yes sorry I’m with ya now! I’m overthinking the idea.
Small insulated shed and temperature controlled heat matt just be work spot on.


Sent from my iPhone using TapatalkWinner good luck mate!

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[rusty_nail]

One thing I thought to.mention, you said you need to consider cable length etc, I figured from a cost perspective but also there is the voltage drop over distance, I'm sure an extra 20m won't have that much effect but might pay to get an elec to advise

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[MB]

Blood Diamonds BOYS Aint Got SHIT ON ‘Cobalt’ [emoji3052][emoji3052]


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[BillsGU]

Have a look at what the industry does. Get some advice (even from the battery supplier). Don't be Robinson Crusoe!

[mihit]

Everyone's pretty well covered it, but I'll chuck my 2cents in.
I'd go a small concrete slab and brick/block bunding for a couple of courses, then light timber or steel frame. Can double-skin it with corrugate (cladding and lining) and fill wall with whatever insulation. expol, glass batts, foam, hemp, whatever.

The BMS should control charging temps, solar panels tend to over-volt in the cold.
...and if you do end up with thermal runaway then temps all become irrelevant reallly quick.


One thing I thought to.mention, you said you need to consider cable length etc, I figured from a cost perspective but also there is the voltage drop over distance, I'm sure an extra 20m won't have that much effect but might pay to get an elec to advise

There are plenty of tables/calculators available online to gauge cable for distance. And the cable supplier should have them on-hand.
48V is pretty copper-friendly, though it's always better to do the long cable runs at higher voltage, ie, put the inverter close to the battery and run 240VAC over the gap, if possible.

6kW @ 48VDC is 125A which would generally be serviced by 2x25-35mm cable and your resistance is going to be in the order of 0.5R/km, so negligible.
6kW @ 250VAC is 25A wich will be serviced by 2c+e 6mm TPS. which if anything like NZ, is going to cost about 1/10th the DC cable.

https://www.engineeringtoolbox.com/wire-gauges-d_419.html

[mudski]

Everyone's pretty well covered it, but I'll chuck my 2cents in.
I'd go a small concrete slab and brick/block bunding for a couple of courses, then light timber or steel frame. Can double-skin it with corrugate (cladding and lining) and fill wall with whatever insulation. expol, glass batts, foam, hemp, whatever.


I do this but a full course of brick all the way up, double brick would be even better for insulation reasons, and a steel frame for the roof and then insulate the roof. I wouldn't use timber at all if I were to do it.

[BillsGU]

Use besser blocks. Cheap to buy and quick to lay.

[mihit]

I wouldn't use timber at all if I were to do it.

Termites, or...???

[mudski]

Termites, or...???

No its just an easier ignition point. Metal is wee bit harder to burn than timber. Its probably a null point anyway, but if the effort was to go into building a structure for reasons as a barrier between batteries and the building it's powering, I'd do the roof frame in steel.

[MB]

Haven’t read properly but ‘Hebel’ block dam pump houses were erected across our region after black saturday intense radiant heat caused petroleum running water pumps to vaporise incoming fuel ⛽️ lines [emoji22][emoji22]


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[mudski]

Haven’t read properly but ‘Hebel’ block dam pump houses were erected across our region after black saturday intense radiant heat caused petroleum running water pumps to vaporise incoming fuel ⛽️ lines [emoji22][emoji22]


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Yeah that'd be the shizz to use. Bigger too so less time to put together.