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What’s with this battery spacing?

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Skypower

Solar Wizard
Joined
Aug 23, 2021
Messages
2,043
Came across this installation. I can’t find any documentation on requiring this much spacing. The whole installation is kind weird. The nice; 3each Sol-Ark 15k on the exterior, 25kw propane generator, 25kw ground mount. I question the spacing, no master DC disconnect inside or exterior, no master PV disconnect near inverters, much of the array will be in shade at any given time and no optimizers. The battery cables are 2/0 and will be the same length(some doubled back in wire way) but cables have no markings. This a totally off grid system currently operating on generator. Some other issues. What do you think?
IMG_7643.jpeg
 
Skypower said:
Came across this installation. I can’t find any documentation on requiring this much spacing. The whole installation is kind weird. The nice; 3each Sol-Ark 15k on the exterior, 25kw propane generator, 25kw ground mount. I question the spacing, no master DC disconnect inside or exterior, no master PV disconnect near inverters, much of the array will be in shade at any given time and no optimizers. The battery cables are 2/0 and will be the same length(some doubled back in wire way) but cables have no markings. This a totally off grid system currently operating on generator. Some other issues. What do you think?
View attachment 178466
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Hmmm, yeah that's odd. I wonder if they think there is a battery fire that the spacing will keep other batteries from catching fire ?
 
JS43 said:
Hmmm, yeah that's odd. I wonder if they think there is a battery fire that the spacing will keep other batteries from catching fire ?
Click to expand...
I was thinking the same, but still, wow. Not
sure if that cable is actually 2/0, looks more like #2.
 
I just had fortress batteries installed and the fire department wanted 3 foot spacing between batteries. Looks like there’s 3’ between the ceiling floor and other batteries in the pic.

If that3’ spacing is a rule, I wonder if EG4 server rack batteries ever get inspected by the fire department to.
 
chrisski said:
I just had fortress batteries installed and the fire department wanted 3 foot spacing between batteries. Looks like there’s 3’ between the ceiling floor and other batteries in the pic.

If that3’ spacing is a rule, I wonder if EG4 server rack batteries ever get inspected by the fire department to.
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The 3' rule comes from NFPA 855. 2020 was the first edition. No more than 20 KWH storage in one location with 3' separation to an additional battery.
 
Oldphile said:
The 3' rule comes from NFPA 855. 2020 was the first edition. No more than 20 KWH storage in one location with 3' separation to an additional battery.
Click to expand...
Not an expert and first time seeing the source. I’m trying to understand a build to code. I know the 3’ rule is still valid because three days ago when I got a fire inspection for the fortress batteries, the fire inspecor liked for 3’.

So to me it looks like the pic in the original post is built to that NFPA code.

The way I read that rule is a 5.12 kWh EG4 battery can not be within 3’ of another battery.

That rule shouldn’t allow you to put two 5.12 kWh batteries in a server rack because the second battery is well within 3’.

It doesn’t mean its OK to have 3 at 15.36 kWh because they’re less than 20 kWh; three batteries are within 3’ and not allowed.

By that code it is certainly not OK to have four batteries at 20.48 kWh.
 
This blog explains it.

You are right about 20.48 KWH. I would think a common sense AHJ would round down to 20 KWH.
 
All
Oldphile said:
This blog explains it.

You are right about 20.48 KWH. I would think a common sense AHJ would round down to 20 KWH.
Click to expand...
OK. EG4 100ah server batteries with 4 in stack should be good.

I see that if UL9540A testing is done, spacing can is waived. EG4 is listed as as UL9540A. The other thing about the EG4 battery, don’t know if this is typical or not, is does a 48 volt 100 ah battery hold 4.8 kWh or should it be rated at 51.2 volts for 5.12 kWh? It comes down to what would an inspector or AHJ determine about that extra 480 watt hours. The advertised capacity does slightly/insignificantly exceed for a rack of four. If its 4.8 kWh per battery, a rack of four does not.


==============
As far as spacing:

“A minimum spacing of 3 feet is required between ESS units unless 9540A testing allows for closer spacing.”

And how much per room:

“The maximum energy rating per ESS unit is 20 kWh. The maximum kWh capacity per location is also specified—80 kWh when located in garages, accessory structures, and outdoors and 40 kWh in utility closets or storage spaces. For storage capacities that exceed these limits, non-residential requirements come into play (NFPA 855 Chapters 4-9).”
 
Oldphile said:
The 3' rule comes from NFPA 855. 2020 was the first edition. No more than 20 KWH storage in one location with 3' separation to an additional battery.
Click to expand...
Presumably there's complete systems approved that are exempt from this requirement (e.g. stacked Tesla powerwalls etc)?
 
Brucey said:
Presumably there's complete systems approved that are exempt from this requirement (e.g. stacked Tesla powerwalls etc)?
Click to expand...


Edit: They must be with 13 kWh powewalls stacked three next to each other.

Could also be a pre ESS code installation
 
Last edited:
Typical. The NFPA lumping battery chemistry types together and making an unnecessary ruling resulting in many installations impossible to comply with due to space constraints. The way I understand it, the biggest danger with LiFePO4, is inhalation toxicity and suffocation if one battery goes up. In any case, you wouldn’t want to spend any time in a large garage if even one battery went up in smoke. A better rule would be to have a smoke detector, ion and/or photo type in the vicinity if there isn’t already a rule. Perhaps a compromised LiFePO4 chemistry detector that would alert people to not enter.
 
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chrisski said:
All

OK. EG4 100ah server batteries with 4 in stack should be good.

I see that if UL9540A testing is done, spacing can is waived. EG4 is listed as as UL9540A. The other thing about the EG4 battery, don’t know if this is typical or not, is does a 48 volt 100 ah battery hold 4.8 kWh or should it be rated at 51.2 volts for 5.12 kWh? It comes down to what would an inspector or AHJ determine about that extra 480 watt hours. The advertised capacity does slightly/insignificantly exceed for a rack of four. If its 4.8 kWh per battery, a rack of four does not.


==============
As far as spacing:

“A minimum spacing of 3 feet is required between ESS units unless 9540A testing allows for closer spacing.”

And how much per room:

“The maximum energy rating per ESS unit is 20 kWh. The maximum kWh capacity per location is also specified—80 kWh when located in garages, accessory structures, and outdoors and 40 kWh in utility closets or storage spaces. For storage capacities that exceed these limits, non-residential requirements come into play (NFPA 855 Chapters 4-9).”
Click to expand...
Another reason to get a newer version of the EG4 batteries.
 
Skypower said:
Typical. The NFPA lumping battery chemistry types together and making an unnecessary ruling resulting in many installations impossible to comply with due to space constraints. The way I understand it, the biggest danger with LiFePO4, is inhalation toxicity and suffocation if one battery goes up. In any case, you would want to spend any time if even one battery puts out smoke in a large garage. A better rule would be to have a smoke detector, ion and/or photo type in the vicinity if there isn’t already a rule. Perhaps a compromised LiFePO4 chemistry detector that would alert people to not enter.
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Great idea. What about an automated exhaust fan and/or louvers?
 
Well I’ve got ion/photo and a heat detector that are tied to the whole house network. They are over the inverters and the batteries are beneath them. I have duct work to remove the heat when it gets over 85F but there’s a thermal fuse in the duct that blows at 163F so that no new oxygen is added into the area. But that would effectively stop any fumes leaving the space too. My diy batteries have isolators between cells and the boxes have been treated with fire retardant and the terminal torque has been checked to the point of OCD, so the chances of fire are near zero. Could they vent in the future from some unforeseen manufacturing defect, sure. The only thing that I don’t have a sensor for is the battery chemistry. I remember seeing some somewhere but I believe they were expensive and had a relatively short service life. My ion/photo detector is so sensitive that I know that by the time get to heat shrink number 6 of 16 balance leads, the detector goes off, so maybe that would suffice for detection for the particles of one cell full value vent release, but not just a leak.
IMG_0815.jpeg
 
Skypower said:
Typical. The NFPA lumping battery chemistry types together and making an unnecessary ruling resulting in many installations impossible to comply with due to space constraints.
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They have a tough battle. For years they limited the quantity of electrolyte you could have in a building, which was completely over the top when you are talking about a lead acid battery system for a >1MW UPS system. Yes, there is a hazard, but they don't create workable metrics or mitigation plans, just an onerous rule that doesn't make sense.

A hydrogen sensor might not be a bad idea (along with heat or ionization), but honestly I would rather just have independent high-precision temperature monitoring of the battery to be used in assessing real-time risk. Putting batteries outside or in a garage you still want something to have a good idea of system health in an alarm capacity.

(The real interesting thing will be if fire marshals start enforcing the minimum recommended room size requirement per the 9540A test results.)
 
Shimmy said:
They have a tough battle. For years they limited the quantity of electrolyte you could have in a building, which was completely over the top when you are talking about a lead acid battery system for a >1MW UPS system. Yes, there is a hazard, but they don't create workable metrics or mitigation plans, just an onerous rule that doesn't make sense.

A hydrogen sensor might not be a bad idea (along with heat or ionization), but honestly I would rather just have independent high-precision temperature monitoring of the battery to be used in assessing real-time risk. Putting batteries outside or in a garage you still want something to have a good idea of system health in an alarm capacity.

(The real interesting thing will be if fire marshals start enforcing the minimum recommended room size requirement per the 9540A test results.)
Click to expand...
Don’t give them ideas(code enforcement) they seem to invent enough rules on their own ?
At my future dream homestead, the inverter/batteries would have their own out building.
 
Probably for fire / maintenance reasons. They also have large spaces between battery banks at the commercial grid tied solar places. Space currently isn't a concern at all. I guess when sodium ion fields cover the planet we'll worry about space

Skypower said:
I was thinking the same, but still, wow. Not
sure if that cable is actually 2/0, looks more like #2.
Click to expand...
judging by the drill size I'd say that wire is 4 gauge..
 
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