Solar power - off grid system

Discussion in 'Electrical' started by cinn, Jun 25, 2018.

  1. cinn

    cinn

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    I have an off-grid system consisting of 6 panels charging 8 deep cycle12v leisure batteries connected in parallel/series to provide 24v DC. I purchased a 5000w inverter from China called Power Jack. On 2 occasions the positive terminal of the battery bank has got so hot it has melted. On each occasion I have replaced the cables connecting bank to inverter with larger cable ( I am now using 10mm cable, the same as that connecting the batteries to each other). I occasionally use a couple of oil filled radiators (1kW and 1.5 kW) during the winter and although the inverter cuts power after approx 1 hr due to low voltage I don't believe it should be pulling so many amps as to cause the terminal to heat up. Today, being rather hot, I tried to run an AC unit off it. It was running at approx 950 Watts and pulling 4.6 amps. When I checked the terminal it was red hot. Clearly this is not right. Also it cut power for low voltage at approx 27v when the, laughingly titles 'manual' states it should be 21v. As far as I am aware all the connectivity is correct, it is not pulling excessive Amps, the resistance of cabling is more than adequate. I suspect the quality of Chinese manufacturing to be the route cause but I'd be glad to hear anybodies comments /
     
    cinn, Jun 25, 2018
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  2. cinn

    Idmason60

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    You need list the Amp hours output for individual batteries.
    8 batteries series,parallel to provide 24 volt and ???? amps hours for storage.
    You need to increase the wiring to match the maximum possible output of those batteries in
    a short period. Rapid discharge of batteries, constant discharge, quick discharges will shorten their life.
    One suggestion, you might want to find another method of heating your structure and
    maybe using solar water heated for both hot water for bathing and hot water for heating.

    Good luck with your project.

    Larry
     
    Idmason60, Jun 30, 2018
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  3. cinn

    piglet11

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    Take care with inverters.
    A faulty inverter in the roof of a pair of houses (semi-detached) near me caused fire in the roof space of one house which spread to the other house roof space. Total devastation of both houses and two years to rebuild.
    The cables to the inverter (low voltage side), need to be BIG (cross sectional size of conductors. You need to get your sums right then add in a safety factor. Any connectors carrying high currents need to be appropriately sized. I would use crimped terminals, not plain screw down. And fit a fire alarm close to the inverter and the high current cables. Also observe all the regs regarding ventilation of cables(i.e. not in thermal insulation etc.)
     
    piglet11, Jul 3, 2018
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  4. cinn

    Johngo

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    IT seems that the positive terminal may not have the connection on secure enough as when you are using the 1k oil heater the inverter is pulling around 41 amps. If the connection is a bit loose to the battery at that level of current draw it will cause it to get hot. To check it take off the terminal clean it well on both battery and cable spray a bit of WD40 on both and reconnect and tighten well. This has happened to me on some other gear and it turned out to be a bad connection.
    Let me know if that fixes the problem.
     
    Johngo, Jul 4, 2018
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  5. cinn

    Bobby the builder

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    Location:
    rockland, ny
    Possible that china uses 50 hz frequency instead of USA of 60 hz ?
     
    Bobby the builder, Jul 5, 2018
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  6. cinn

    Bobby the builder

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    Location:
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    you may have a mechanical connection but not good electrical connection due to resistance from corrosion, clean the connection and use electrical grease instead of oil. lubricants can act as an insulator and WD is not a lubricant anyway it is for water displacement. this helps with the mechanical connection but you possibly need a better electrical connection
     
    Bobby the builder, Jul 5, 2018
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