what size cord for 10 foot run generator to charger

solarsquirral
solarsquirral Solar Expert Posts: 54 ✭
in General Solar Power Topics #1
hi guys sorry if this is a silly question
i know i could look at a chart to see what wire can support how many amps but i thought id ask your opinion

i have a 3500 watt generac generator that ive hooked up directly to my m1512 inverter which has a built in battery charger

it has a setting to charge anywhere from 20 -60 amps

on the genny plugs it has 30 amp breakers

does that mean i could only charge up to 30 amps
or it the conversion from ac to dc doing something different

the plugs on the genny are three prong but they also have that little thing for plugs that i see with 20 amp awg 10 plugs(one plug kinda looks like a t)

what size wire do you run from your genny to your charger

right now if been useing 12awg (might be too small)

when charging the meter on the inverter goes to bulk and show 22 amps in

will running thicker wire give me more amps
or is this the charger deciding not to run too much power to the batterys

thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: what size cord for 10 foot run generator to charger

    In general, you should not run more current than 80% of breaker/wire ratings (except for short term surge current):

    30 amps * 0.80 = 24 amps max continuous

    Larger diameter wire means less losses (i.e., 1% loss vs 3% or 5%)--Wire costs more--Your choice.

    There can be a secondary issue--With generators (and AC inverters), they have limited surge capabilities (compare to 10,000 Amps max surge from a utility pole transformer).

    Heavier wiring has less resistance, and can allow higher surge currents (for example, starting a well pump takes something like 5x surge current over operating current). And it is possible that the Genset or Inverter will have problems starting "surge-y" loads with heavy AC wiring.

    Another note--Make sure you know where the 20 amps is you are talking about--It is 20 amps at 120 VAC side of the inverter or 20 amps at 12 VDC side of the inverter/battery system. It is not always clear from the manuals/inverter meters at times which side of the inverter-charger (120 VAC or 12 VDC) they are taking about when programming limits/reading their display.

    There is a big difference to the generator/inverter hardware:

    20 amps * 120 VAC = 2,400 Watts
    20 amps * 12 vDC = 240 Watts

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #3
    Re: what size cord for 10 foot run generator to charger
    does that mean i could only charge up to 30 amps
    or it the conversion from ac to dc doing something different

    30 ac amps is probly 300 dc amps at 12 volts.
    right now if been useing 12awg (might be too small)

    10 awg is probly ok, 8 awg would be better.
    when charging the meter on the inverter goes to bulk and show 22 amps in

    Depends on the inverter what you are looking at. I believe outback shows ac amps on the mate which would make 22 amps 220 amps going to the battery. I don't know what your inverter does.
    will running thicker wire give me more amps
    or is this the charger deciding not to run too much power to the batterys

    It will be your inverter deciding how many amps to charge with. The wire change would be for safety. is your wire getting hot when in use now?

    I didn't get a caculator out but just did my 20 amp generator and it called for 10 awg min.
    Good luck
    gww
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  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    #4
    Re: what size cord for 10 foot run generator to charger

    If I read this post correctly, your inverter is using 22 amps at 120 volts. I personally doubt that the generator puts out 30 amps for long, if ever.
    That said, your #12 wire will work ok. Does it overheat? If not, you can continue to use it. All wiring runs have some losses. These increase as the wire size gets smaller and as wire length gets longer. 10' isn't particularly long IMO. There are numerous places on the net where you can get power losses for different wire sizes.

    So, you could increase your extension wire size and will gain a "small" amount of extra current.

    Keep in mind that as wire size gets to 10 or 8 guage, it becomes harder and harder to manipulate the wires inside of receptacles, plugs etc.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • Mountain Don
    Mountain Don Solar Expert Posts: 494 ✭✭✭
    #5
    Re: what size cord for 10 foot run generator to charger
    Keep in mind that as wire size gets to 10 or 8 guage, it becomes harder and harder to manipulate the wires inside of receptacles, plugs etc.
    ... and the larger wires may not fit into the receptacle or plug connection points.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #6
    Re: what size cord for 10 foot run generator to charger
    ... and the larger wires may not fit into the receptacle or plug connection points.

    I actually just built a cord to my breaker box to a L14-20 20 amp plug with 8 awg and though tight, It did fit. I would have used 10 awg but 8awg is what I had on hand. in the manual for my generator, it said to use 10 awg to a manual transfer switch. My generator is a devilbiss 5000 watt generator that is 20 amps per 120 volt stator. I don't say 12 gage is bad if it is not getting hot, I just say what was recomended by my generator manufactuer.
    Good luck
    gww

    PS I just bought a 10 awg ten foot cord. I saw cords for sell with as low as 14 awg being sold for 20 amps.
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