110V 3/4hp 11.2amp Electric Motor Start up Current?

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Hello,

After searching the forums for a few days, and learning alot about electric motors, mostly in well pumps, I decided to post and ask if my idea below is feasible.

I'm trying to set up a solar system that will power a boat lift with a 110V, 3/4hp electric motor with 11.2 amps listed on the spec plate. I plan on using the lift 1-2x/wk for a total of 6-7 minutes/wk

How do you determine the total start-up current so I can start building a system that will supply it?

After reading the forums I'm pretty sure its not the 11.4amps listed on the spec plate. I'm not sure if I need to know total lift weight, mechanical advantage of the lift system etc. to determine this or can a general rule of thumb be applied so I select the proper Inverter.

Thanks for any help,

Randy
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Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: 110V 3/4hp 11.2amp Electric Motor Start up Current?

    Rule -o - thumb is 5 to 10x the run current = starting current. Depends on load on the motor when starting. A "PEAK hold AC Ampmeter" ($300) will tell you for sure, you may be able to find an electrician, who for a beer and afternoon of fishing, may hook the meter up, and you take an average of 5 starts.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: 110V 3/4hp 11.2amp Electric Motor Start up Current?

    Thanks Mike.

    I noticed you run a 1/2hp 240V well pump. Being new to this can I ask is it better to run 240 versus 110 ie less draw from a solar system in overall power or amps?

    Love the Simpson 3-eyed fish avatar. If I remember that episode his name was Blinky LOL.

    Randy
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Re: 110V 3/4hp 11.2amp Electric Motor Start up Current?

    Power = voltage*current

    So running at 240 vac will simply be half the current vs 120 vac. No major difference in power from the inverter or battery bank.

    So less voltage drop and/or smaller gauge wire required.

    But, on the other hand you will have the cost and losses of the transformers, which is not insignificant.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    Re: 110V 3/4hp 11.2amp Electric Motor Start up Current?

    I have a 400' run from my inverter, to the pump, and I have a 240V inverter, the 240V pump keeps the load balanced on both legs, and less loss in the long wire run.
    If you can't get a 240 V split phase inverter, you need a transformer. But you can wire the transformer primary side to the pump switch, and only run it (with it's 5% loss) when the pump runs. Must be a pure sine to run large motor and / or transformer. Mod sine will not give happy results
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

    · Share on Twitter

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