Batteries below controller & inverter

Moe
Moe Solar Expert Posts: 60 ✭✭
in Off Grid Solar & Battery Systems #1
I'm still waiting for my copy of the NEC, but I read in the NMSU PV-NEC-V-1.91.pdf that batteries can't be kept below an inverter or charge controller because of the outgassed hydrogen and oxygen being ignited by spark.

How heavily is this enforced? I see a lot of pictures of setups with these above a battery bank and it makes sense for keeping cables short.

If it matters, I had planned to use L-16 AGMs open on a 4" platform on the floor in a garage corner, with the FLEXpower One mounted on the wall above them (12 inches clear to the corner). The batteries project out about a foot and the FP1 is 13 inches deep.

Thanks!
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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #2
    Re: Batteries below controller & inverter

    This restriction is primarily due to the corrosive stuff emitted from FLA batteries as well as hydrogen. I use FLA L-16's and am very aware of this corrosive effect. I dont think AGM's will be an issue since they are not supposed to outgass anything in normal circumstances. Take this as only my opinion and not based on fact, I am not an AGM battery expert. Hopefully folks more knowlegable will chime in.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Batteries below controller & inverter

    i doubt that the nec is distinguishing between battery types and i recall that this was brought up before on the forum. i haven't seen the ruling, but it would make for longer wires between the cc and batteries and the inverter and batteries and this would lead to higher losses with larger wires needed to overcome these losses. if memory serves from the other thread they are insisting on the batteries being 5ft away.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Batteries below controller & inverter

    It also assumes there is a clear path from the batteries to the equipment; i.e. the batteries are not within a vented box. In reality it is quite normal to locate controller and/or inverter directly above the batteries. It does not take much to control the vented gas and vapour.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
    Re: Batteries below controller & inverter

    Mine are just off to the sides and above. Controllers to the right, inverters to the left, all are outside the convection vented battery box in the solar shed. Box is insulated in Winter, insulation removed for Summer. L-16's are 18" up off the floor, makes for easier servicing of everything. Lid on battery box is slanted 35* so I can't pile junk on top, it all slides off on the floor.:p
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #6
    Re: Batteries below controller & inverter

    There is also a code rule about 36" of clearance around electrical equipment for service access.
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  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    #7
    Re: Batteries below controller & inverter

    Thank you all. I'm hoping to not have to use a box, given they're AGMs in a garage. I had thought of a well-tilted piece of plywood on top to keep things from dropping on them. I can also put them under a workbench to the right, but will have to use longer cables and relocate the air compressor to under the FLEXpower (hung further out from the wall so as not to have to bend over the air compressor to reach it).
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #8
    Re: Batteries below controller & inverter

    You still need a box. To protect the live connections from shorts, to protect the cables from damage, to protect the batteries from damage. You will also want to insulate the batteries in the winter since they'll be in your garage (assuming you are in a cold area).
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #9
    Re: Batteries below controller & inverter
    Controllers to the right, inverters to the left,
    almost sounds like a Jimmy Buffet song:D
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #10
    Re: Batteries below controller & inverter
    mikeo wrote: »
    almost sounds like a Jimmy Buffet song:D

    Haha That one totally missed me at the time, one tracked mind - :p:p:p
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  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    #11
    Re: Batteries below controller & inverter
    techntrek wrote: »
    You still need a box. To protect the live connections from shorts, to protect the cables from damage, to protect the batteries from damage. You will also want to insulate the batteries in the winter since they'll be in your garage (assuming you are in a cold area).

    What do you use for insulation? Must it (particularly foam) be fire-protected (i.e. covered with taped and mudded fire-resistant sheetrock) on the interior?

    Thanks!
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #12
    Re: Batteries below controller & inverter

    Mike,

    Think it was from a "Stealer's Wheel" song ...

    I've put my FLA bank in insulated, ventilated plywood boxes, with hinged lids. Styro or Styro/Polyisocyanurate foamed insulation, up to three inches thick.

    I am beginning to believe that very much insulation at all can cause the battery temps to rise in our summers. Recently have been running an experiment, of leaving the bat box cover open day and night, and this helps moderate bank temp rise. FLAs, being less efficient than AGMs (for example), in an insulated box, can see the temp rise a bit each day, and with good box insulation, it is difficult for the box to get rid of the heat.

    This is a bit off the target of the thread, tho.

    Most of my battery banks croud the Code for space in front of electrical panels, opting for the shortest leads twix the inverters and batteries. The DC side of the inverters are crowded, but the AC side easily meets the clear space spec. Altho, seem to recall that the required space if for systems of 0-2000 volts or some such, so the 48 VDC on the crowded side might not quite fly in a nit-picking inspection.
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #13
    Re: Batteries below controller & inverter
    Moe wrote: »
    What do you use for insulation? Must it (particularly foam) be fire-protected (i.e. covered with taped and mudded fire-resistant sheetrock) on the interior?

    Thanks!

    I once had a wire fuse itself next to regular fiberglass insulation. There was a burn mark on the fiberglass at the point of ignition but it did not support continuos flame.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #14
    Re: Batteries below controller & inverter

    I use fiberglass. Two reasons.
    1) Will not burn. But if you put a blow torch to it, heating it red hot, you can however get it to melt down into little beads of glass.
    2) Unlike styrofoam, it compresses to squeeze into place, then expands up against the batteries, preventing convection air currents which would carry away heat.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #15
    Re: Batteries below controller & inverter
    waynefromnscanada wrote: »
    .....then expands up against the batteries, preventing convection air currents which would carry away heat.

    In summer the fiberglass could be easily pulled.
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  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    #16
    Re: Batteries below controller & inverter

    This is good discussion! While it seldom gets below the teens, we see single digits and have had a low of -23ºF. Never had anything freeze in the garage though. On the other hand, we get some days in the 90s and after pulling the vehicle in, we have to leave the door open to keep it from getting really bad inside. Sounds like I need to think about not only insulation, but also outside air intake for cooling, not just for the humans. I think Concorde requires 1/4" clear around each battery.

    Thanks, all!
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  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    #17
    Re: Batteries below controller & inverter

    My controllers & inverters are mounted directly above my 8 T-105 type batteries. I do keep a sheet of Lexan sitting on top of the batteries. Not only does it prevent spitting of battery acid, but more importantly, prevents accidental shorting if something gets dropped.

    I also have a sheet of Lexan over my bus bars for protection against shorting.

    This setup has worked very well for the past 4.5 years. Corrosion has not been an issue. Because I can SEE all the battery connections, I can quickly address anything connection that's less than perfect. Never had any issues with corrosion at the charge controllers, or the inverters.

    My batteries live in a FL garage. Freezing is never an issue. 90+ temperature is common most of the year. Keeping the fluid levels up is more of an issue than anything else.

    My garage is also vented, with a couple of brushless fans. If off-gassing was a potential issue, I would build a battery box, with an external fan, but also stick with a Lexan lid to retain the ability to visually keep an eye on the batts.
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  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    #18
    Re: Batteries below controller & inverter

    Lexan covers--that's a great idea! Thanks!
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  • Battling Bob
    Battling Bob Registered Users Posts: 20 ✭
    #19
    Re: Batteries below controller & inverter

    Out here in northeast Oregon, I've gotten great service from a battery box built of 1x lumber, lined with aluminum newsprint master sheets (great, great stuff--a little inky, but just like super aluminum foil, and usually available for salvage price from your area newspaper publisher). The undersurface of the lid slopes upward from one end to a 2-1/2" pipe outlet on the other end. The pipe connects to a vent located six feet up the wall--outside I have a horizontal tee of the same pipe, with screens on either end to keep the wasps out. In the floor of the battery box, I've drilled several holes clear through the house floor.

    The "tee" outside gets a little suction effect going with any breeze, drawing air up from the crawl space and out through the battery box. Since this is all inside the house, everything stays within about twenty degrees of the same temperature winter and summer alike. With a heavy dusting of baking soda on the floor of the battery box, the arrangement has served perfectly for 12 years now--zero corrosion on my terminals, no problem with the batteries, no fumes in the house even when equalizing.

    All located about eighteen inches below my double Trace inverters... As for code, who knows? We're pretty far out in the boonies.
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  • jvcyclist
    jvcyclist Registered Users Posts: 11 ✭
    #20
    Re: Batteries below controller & inverter

    Just as a data point, we recently were actually recently inspected by the State inspector. Our batteries are 3308 Surettes in a box directly below the electronics. I did make sure the opening of the conduit running the battery cables up to the electronics was well below the top of the box, and the box is actively vented to the outside (everything is in a windowless room in the house...so no insulation per se).

    At any rate, the inspector didn't blink an eye wrt the battery box. That may represent the fact that he doesn't have a sufficient knowledge base to know what he doesn't know, or that we did it right.

    We also have (my paranoia) a H2 detector up near the ceiling near the battery box...it can be used to trigger a vent fan if it detects a 1% concentration. We will hook up vent fans the first time that happens. It hasn't yet.

    Jim
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  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    #21
    Re: Batteries below controller & inverter

    Thanks for those examples. Sounds like it's up to the individual inspector.
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