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A DIY Power Wall ???

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  • #31
    Originally posted by NEOH View Post
    RE: The "fire" in message #12 ( two posts above )

    What is the "fire code" for the Power Wall?
    Must it be installed on a non-flammable wall - like brick?
    What if it is mounted outside on a vinyl sided house with a wood substrate = major fire hazard?
    The Insurance companies will have a problem with this increase risk.
    They hate anything that increases their risk of lost profits, and rightly so.

    Are these PowerWalls ever installed inside the home - in the living quarters? in the basement?
    It look like a significant amount of toxic smoke & fumes were released.

    If each cell is individually fused, then how did the first cell catch fire, as seen in message #12 ?
    If the individual fuse did not blow then one or more the cell(s) overheated while operating at "normal" amps.
    So then the Temperature Sensor, if there is one, failed too?
    At some high temperature, the circuit should have opened and stopped all charging amps or discharging amps, long before the ignition point?
    Is it possible for a cell to continue in thermal run-away, even after the circuit is opened?

    You can't (cheaply) monitor the temperature of each and every cell, so this seems to be very risky in hot weather.

    Does it make more sense, from a safety point of view (increased cost), for each cell to fully protect itself from volts, amps & heat ?
    Then the manufacturer can add another layer of safety to the battery pack as whole.

    If this passed inspection then it must be UL Approved".
    I wonder how UL tested these battery packs?
    Regardless of what "code" may say, by asking the question I assume you already know that it is a good idea or at least couldn't hurt. Since I'm only at my off-grid location, my CC and inverter are installed on a Durock sheet with an Durock cover, never hurts to go beyond code requirements.
    1150W, Midnite Classic 200, Cotek PSW, 8 T-605s

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    • #32
      Originally posted by derekisastro View Post

      Isn't that common knowledge? All other things being equal ... cycle life, from lowest to highest is ... FLA < AGM < Li-Ion < LiFePo ...

      I mean ... you might be right in saying that FLA can have 1000 at 1/4 the cost ... but then doesn't a GOOD LFP have 3000-5000 cycles? Essentially, 4 times the cost for 4 times the life?

      I'm definitely still learning, so am keen to see some good solid data on all of the battery options ... it's sometimes hard to separate the chaff from the wheat when it comes to data on batteries it seems?
      If you were to bother to look at the actual battery manufacture specs, you would know only 1 claims to last 1000 cycles, while top of the line FLA batteries run as high as 5000 cycles. So much for make believe science.

      The best LFP battery money can buy is A123 Systems, and they only claim 1000 cycles but fail to provide anything more than a 1 year warranty. A123 Systems batteries will run you $1.50 per watt hour. On the other hand a top of the line Trojan Industrial battery will provide 3000 cycles @ 80% DoD and comes with a 10-year warranty and cost on the order of $0.20 per watt hour.

      So if you were to take say a 6-volt 400 AH Trojan Industrial battery gives you 2400 watt hours of capacity and will cost you roughly $500 with a 10-year warranty. Want that in a quality 6 volt 400 AH LFP battery? That will cost you $3600 plus you will need to fabricate a case and use an expensive BMS to make it work so in the end cost you about $4000 with a meaningless 1-year warranty.

      So I say go for the LFP, you deserve it and will learn something.
      Last edited by Sunking; 12-24-2018, 08:24 PM.
      MSEE, PE

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