Looking for ideas for "enclosure" for lithium batteries used in homebrew 'powerwall'

[LTC-J]

Title is the short.

Long:
I've heard of way too many cases of lithium based batteries catching fire and doing significant damage.

To mitigate this, I'm looking at some type of "enclosure" for the batteries I'm going to use in a homebrew powerwall at my primary house; actual equipment and number of batteries are still in the air.

I've got a 50% walk in crawl space under my house that I intend to use for storing batteries and other needed equipment.

I've got a section that is flat ground about 3-4 feet below the floor joints of the house. I can go 3' deep and easily over 8' long(96++++ cubic feet of space); in other words, plenty of room to add batteries to increase capacity

For placing the batteries on the ground, is it worth going concrete? Or is putting them on fire rated plywood and 4x4 good enough?

What type of 'racking' should I do if needed? Plain steel? I could just go with pallet racking to get heavy duty two stacks that doesn't touch the ground.

What do I need to do between the batteries and my floor? Steel? Fire plywood?

What about sides? Fire plywood?

In theory, I could put a 'fire' vent to the outside pretty easy; ie tubing to outside the house.

Am I overthinking the safety?

[TheChief]

Investigate LiFePO4 vs Lithium-Ion battery fire concerns.

Cant help you with the rest of the questions other that general concern of ground water, rains, etc. with storing hi-power systems next to or underground that have not been designed by trained engineers.

[LTC-J]

Investigate LiFePO4 vs Lithium-Ion battery fire concerns.

Cant help you with the rest of the questions other that general concern of ground water, rains, etc. with storing hi-power systems next to or underground that have not been designed by trained engineers.

Thanks for something to look into. I'll take a scan

The location I have in mind has zero water intrusion in 5+ years I've lived at the house even with 4'+ of standing snow.

[Mongoos913]

A lot of RC guys use ammo boxes to store Lipos. They either drill a few vent holes or remove some of the rubber gasket in the lid. This help release pressure and eliminate possible explosion. Some line the inside with either drywall or backerboard. YT has a bunch of vids for ideas.

[b18bturboek9]

Was going to say ammo boxes or cans but to be honest you should look into lithium phosphate batteries. The only problem with those would be really cold temperatures, but they have a longer life cycle and less of a fire concern.

[user120312]

I got the newer lithium iron phosphate versions for my small system, which is installed in the pump house back by the creek. It's cool there year round and the space has heating for extreme cold snaps that can run off the battery bank to warm the pipes and batteries.

I remember flying the early 787's when they had problems with the then new lithium batteries overheating and catching fire. Perhaps look into the safety/containment systems Boeing came up with to handle those issues.

[edgerly779]

Good advice so far. OP should use google to research liFePo4 batteries. Never lithium ion. Look up dive boat Conception story for how to burn your house down with lithium ion batteries. If you use lion put them in brick enclosure away from structures.

[LTC-J]

So LiFePo4 batteries are relatively safe? I'm not planning to completely cheap out on the construction of the system.

I'm not hugely worried about cold. The worst I've seen at my location is mid upper teens... maybe four times in six years. I may wrap the batteries in water line heaters.

I'll see if I can find anything about Boeing solution. But figuring out a homebrew solution is the reason for this thread.

There are many reasons for the location I'm considering:
1) Convenient and out of the way. I almost never go into the crawl space so it is out of sight, out of mind.
2) Close to subpanel. It is less than 10 feet so a saving in cost there. One out of the way spot for an outbuilding is about 40 feet from subpanel. Other 'easy' spot is closer to 80 feet from subpanel.
3) Less stuff to build. I don't need to build an out building. I don't need to trench. I don't need to 'bore'(4' concrete steps against wall that I'd have to go under). Granted, I can toss a generator in the outbuilding and toss a couple of solar panels on top.

[michaelf3]

When you say powerwall, how big (kW) or what's your budget? There might be already built solutions that are comparable in price to self build and are very safe.

[broadside]

What voltage system? EG4 rack batteries are becoming very popular in the 48v RV world for big systems. Since rack mountable that would address one of your issues. Being LiFePo4 would help with fire concerns.

[LTC-J]

When you say powerwall, how big (kW) or what's your budget? There might be already built solutions that are comparable in price to self build and are very safe.

I'm still doing some 'backwards' calculations to get my number. It may end up about 'half' my house.

My initial 'setup' is going to be a large bank of batteries feeding my 'half house' subpanel. The batteries will be charged from main panel while power is on and by a generator when power is out. Eventually I'll add in solar, wind, and water charging options for the batteries.

I won't say unlimited budget but I will initially spend big money on the hardware (inverter, chargers/charge controllers, monitor) with a smaller capacity while I figure out ultimate desired capacity

What voltage system? EG4 rack batteries are becoming very popular in the 48v RV world for big systems. Since rack mountable that would address one of your issues. Being LiFePo4 would help with fire concerns.

I'm still researching what voltage to shoot for. Since I have zero equipment, it will be easier to get 'correct' equipment. With zero research, I'd guess 48V will be more efficient... then the question is whether equipment is similar priced for 12V, 24V, and 48V.

'Storage structure' is the cheap part of the equation. A two shelve 2x8 pallet rack is dirt cheap(~$200 last set I bought that I could repurpose) and will hold 2k pounds per shelf So I'm not sure paying for the EG4 rack batteries is worth the investment.

[broadside]

I'm still doing some 'backwards' calculations to get my number. It may end up about 'half' my house.

My initial 'setup' is going to be a large bank of batteries feeding my 'half house' subpanel. The batteries will be charged from main panel while power is on and by a generator when power is out. Eventually I'll add in solar, wind, and water charging options for the batteries.

I won't say unlimited budget but I will initially spend big money on the hardware (inverter, chargers/charge controllers, monitor) with a smaller capacity while I figure out ultimate desired capacity



I'm still researching what voltage to shoot for. Since I have zero equipment, it will be easier to get 'correct' equipment. With zero research, I'd guess 48V will be more efficient... then the question is whether equipment is similar priced for 12V, 24V, and 48V.

'Storage structure' is the cheap part of the equation. A two shelve 2x8 pallet rack is dirt cheap(~$200 last set I bought that I could repurpose) and will hold 2k pounds per shelf So I'm not sure paying for the EG4 rack batteries is worth the investment.

Well the EG4 are the go to for 48v RV systems due to price per watt-hour right now. 12v is not efficient for large systems plus if you are powering a lot then the wiring and terminal sizing needs to be a lot larger. 24v lets you step down wire size and related costs, 48v even more so.

The cost issue will be the inverters and chargers/controllers. Cost difference is almost nothing between 12 and 24v. 48v the costs go up a bit. But if you need a lot of wiring components you can offset some of that difference.

[edgerly779]

Most hybrid Inverters I buy are 48vdc 6.2-10 kw. Battery arrays are minimum 4.8kw 100 AH. I never use 230 vac micro inverters. I have some enphase for sale on here IQ7PD-72. I do not get involved with grid tied systems. All our properties are off grid.

[sealocan]

I didn't read every response but my first thought would be putting whatever you create on wheels so that if something does go wrong you can pull it out of your home or underneath your home and get it away from causing more damage.
plus that would make it easier to maintain everything as well.

[LTC-J]

I didn't read every response but my first thought would be putting whatever you create on wheels so that if something does go wrong you can pull it out of your home or underneath your home and get it away from causing more damage.
plus that would make it easier to maintain everything as well.

There is a 3' or so lip to go from crawlspace to basement then to outdoor But good point on mobility. OTOH, shuffling 300-400lbs of equipment probably isn't practical even without the lip

Most hybrid Inverters I buy are 48vdc 6.2-10 kw. Battery arrays are minimum 4.8kw 100 AH. I never use 230 vac micro inverters. I have some enphase for sale on here IQ7PD-72. I do not get involved with grid tied systems. All our properties are off grid.

There will be zero direct grid tie in with my 'alternate power solutions'... ie I am NOT going to feed a single watt to PGE.

My high level solution will be as follows:

• PGE fed main electric panel
• Battery solution feeds inverter that feeds a second panel that has some/majority of house electrical needs(220V feed)
• Battery solution is charged by one or more of the following: solar panels, wind mill(s), water wheel(s), generator(s), and 240V battery charger fed by PGE main panel

The last part is the only real intended 'tie in' with PGE. PGE power will charge batteries if the alternates are not installed or not available. My current plan is to get batteries, inverter, and quality 240V battery charger(I'm assuming more efficient/quicker than 120V charger)

What I'm currently running into is most 'inverters' seem to be inverter/PV charger combos. Some seem to have 'PGE' input as well as generator input.

I am hoping to find a multi input charger controller that will handle multiple sources of 48V that will feed/charge the batteries.