Magnum 4024PAE and 1hp well pump - bit the bullet

bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
Well, I have bit the bullet and ordered a Magnum 4024 PAE inverter in the hopes it will start our 1 hp well pump -3 wire single phase.

I'm NOT getting rid of the well pump because we get 42 GPM from it and want that for irrigating if we have to grow all our own food. Yes, I'm a bit of a prepper. And that why we're going to 24v rather than 48v. If a battery bites the dust I'll still have a battery bank, just smaller. Most of our loads are under 500 watts combined anyway.

We already have a Magnum 2012, and I have found their techs to be wonderful, especially Glenn, always gracious when I call to ask him about stuff like this. American company, American people - can't be beat!

We pump into a 3000 gallon tank, so it will only have to turn on once a day, or as little as one every 10 days in the winter, I turn it on manually after starting a generator right now. It's the gennie and fuel that I want to be independent of.

We are upgrading the 800 watts solar to about 2200 watts, and the battery bank will double to 790 amps/24 v. Hoping that with the batteries at 90% or more and the sun giving us it's best around 10-11 am that we can start the pump. Running it (2000 watts) will not be a problem, just the startup.

The problem is in the locked rotor amps. For our pump it's 41.8 amps. The pump motor (Franklin) technical dept assures me that this amperage is at the start and lasts about 300 milliseconds but they cannot tell me how fast it falls off from 0 to 300 msec. The Magnum max amps is 70 at 1 msec and 40 at 100 msec. The Magnum techs say the 40 amps max at 100 msec is very accurate.

So there's that mystery 2 msec where I don't know if the pump will get down to 40 amps or not....only trying it will tell me.

There are soft start possibilities, but the only two that I know the pump companies will recommend for my pump cost $700 plus. We decided if that's what it takes we will get that too, but they are constant speed controls as well as soft start, so we will be paying for stuff we don't even need. We may even wire them just to start the pump and then turn off, allowing the normal full 240 volts through. Perhaps just a break/make switch.

Anyway, I put this out here for those in the future who wonder about the Magnum 240v inverter and a 1 hp pump. I will update how it works when we get it all up and running.
Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet

    You should be fine. I run a 3/4 hp on a Xantrex Freedom 3000 watt without a issue. Even though it's a 24 V inverter, don't skimp on the cables, I'd do 4/0 all the way through. If your filling a open loop tank, you'll have very little head pressure to deal with. You do know that that at 240 volts you'll only get 1/2 output per leg ?
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet
    You should be fine. I run a 3/4 hp on a Xantrex Freedom 3000 watt without a issue. Even though it's a 24 V inverter, don't skimp on the cables, I'd do 4/0 all the way through. If your filling a open loop tank, you'll have very little head pressure to deal with. You do know that that at 240 volts you'll only get 1/2 output per leg ?

    Not half the total wattage output, half the amps per leg. But the pump is 230, so it needs both legs anyway. Watts are the same for 230 versus 110, just the amps per leg change.
    4000 watts at 110v on one leg = 4000 watts at 240v on two legs. As long as the wiring is right.
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet
    bbbuddy wrote: »
    Not half the total wattage output, half the amps per leg. But the pump is 230, so it needs both legs anyway. Watts are the same for 230 versus 110, just the amps per leg change.
    4000 watts at 110v on one leg = 4000 watts at 240v on two legs. As long as the wiring is right.
    Based on your post it sounded like your upgrading your system. Where you run into trouble is if you have other loads on the same inverter and you have a imbalance on the draw and try to start the pump. Just making a point for you to consider. Anytime your maxing out a Inverters capability there things to consider.
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet

    Thank for the tip. No, we will only start the pump when the inverter is unloaded. Once started, the max loads would be around 300 watts, for a total of 2300 watts.

    Shouldn't bother the inverter a bit, because we will have nearly 2000 watts coming into the batteries at the same time, the inverter will have plenty of "juice" behind it.

    It's just the actual startup I'm nervous about....
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
  • Texas WellmanTexas Wellman Solar Expert Posts: 153 ✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet

    Did it work? Just curious to see how it turned out.
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Magnum 4024PAE and 1hp well pump - bit the bullet

    Sorry, just saw this question.
    We don't have it up and running yet, still building the mounts for the new panels, and need to get them mounted before we try it out. will post the results here as soon as we know.
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
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