240V single phase inverter to split phase?

[MtnGuy]

I bought a 12V, 2000W/4000W inverter principally to power my 240V well pump at my cabin during somewhat limited and sporadic power down scenarios. Using an amp clamp, I had measured the power draw of the well pump of about 1800W. I have a 400W solar array with about 220Ah 12V battery array.
I got ahead of myself and bought a 240V pure sine inverter not thinking about it being a single phase inverter and how the well pump is a split phase. Is there any way to get this inverter to work as-is, or am I looking at buying a transformer or a whole new inverter? If a transformer makes more sense, can anyone recommend one? I assume I can't just feed it 240V on L1 and leave L2 unused.

Thanks in advance!

[Mike90250]

It might work OK, IF the inverter is stout enough (and the battery & cables are in great shape) to handle the starting surge of the pump. A 12V system is good to about 1,000 watts

Voltage sag from the battery being to heavily loaded, could trip the inverter offline. Here's a table of general startup surge. A 2K/4K inverter may be hard pressed to start the pump

Well Pump Motor Specs.jpg

[MtnGuy]

Thanks. So then I could just wire the 240V single phase inverter to one of the 120V legs of the pump and whether the pump works or not would depend on whether the inverter and initial voltage hit in a 12V array could handle it, right? Do you think it's safe enough to try from the standpoint of not damaging the motor?

[sensij]

Thanks. So then I could just wire the 240V single phase inverter to one of the 120V legs of the pump and whether the pump works or not would depend on whether the inverter and initial voltage hit in a 12V array could handle it, right? Do you think it's safe enough to try from the standpoint of not damaging the motor?

"One of the 120 V legs"... Seriously, stop what you are doing. Trying to supply >2000W from a 12 V battery at your level of electrical knowledge is really dangerous. Please get some qualified help.

[NEOH]

I bought a 12V, 2000W/4000W inverter principally to power my 240V well pump at my cabin during somewhat limited and sporadic power down scenarios. Using an amp clamp, I had measured the power draw of the well pump of about 1800W. I have a 400W solar array with about 220Ah 12V battery array.
I got ahead of myself and bought a 240V pure sine inverter not thinking about it being a single phase inverter and how the well pump is a split phase. Is there any way to get this inverter to work as-is, or am I looking at buying a transformer or a whole new inverter? If a transformer makes more sense, can anyone recommend one? I assume I can't just feed it 240V on L1 and leave L2 unused.

Thanks in advance!

Q1) What is the Model # of your DC-to-AC inverter?
Q2) What is the Model # of your Deep Cycle battery & how many?
Q3) Why do you think your pump requires "Split Phase" 240 Volts AC?

Typically, 240 Volts is provided via the L1 (Black) wire and the L2 (Red) wire.
The White wire is the neutral.
The Green wire is the ground.
What wires do you actually have going to your pump?
Many pumps do not use the Neutral (White) wire.

1,800 Watts ( running ) / 240 Volts AC = 7.5 Amps AC
1,800 Watts ( running ) / 12 Volts DC = 150 Amps DC <<< WOW !!!

Your battery bank will be "dead" in about 30 minutes of pump operation.
Why did you select a 12 Volt DC Inverter vs a 24 Volt DC Inverter vs a 48 Volt DC Inverter?

Typically, when starting the well pump, the amps will surge, up to 5 times the running amps for a short period.
Will your DC-to-AC Inverter support this short burst of 38 Amps AC = 9,000 Watts ?
Will your DC wire and Battery Bank support this short burst of 750 Amps DC ?

When generating your own AC Power, you need to supply Peak Power, not just running power.

[MtnGuy]

"One of the 120 V legs"... Seriously, stop what you are doing. Trying to supply >2000W from a 12 V battery at your level of electrical knowledge is really dangerous. Please get some qualified help.

Please spare me the condescension - I've already stopped. I'm open to replacing my controller with an MPPT, rewiring my panel and battery arrays in 48v series and replacing my inverter with a 48V to 240V split-phase if necessary, but the last moderator said that my current inverter setup might work, so that's why I asked how. Asking questions is why I'm here. If this is a 'redirect you to an electrician forums', that's cool, and I'll be on my way.

[J.P.M.]

Please spare me the condescension - I've already stopped. I'm open to replacing my controller with an MPPT, rewiring my panel and battery arrays in 48v series and replacing my inverter with a 48V to 240V split-phase if necessary, but the last moderator said that my current inverter setup might work, so that's why I asked how. Asking questions is why I'm here. If this is a 'redirect you to an electrician forums', that's cool, and I'll be on my way.

FWIW, that looked more like a well meant and well placed safety first suggestion that you seem to have already agreed with than condescension. Besides, all of the comment here is free, and you get what you pay for, or less. Opinions vary and none of us is as smart as all of us.

[MtnGuy]

Q1) What is the Model # of your DC-to-AC inverter?
Q2) What is the Model # of your Deep Cycle battery & how many?
Q3) Why do you think your pump requires "Split Phase" 240 Volts AC?

Typically, 240 Volts is provided via the L1 (Black) wire and the L2 (Red) wire.
The White wire is the neutral.
The Green wire is the ground.
What wires do you actually have going to your pump?
Many pumps do not use the Neutral (White) wire.

1,800 Watts ( running ) / 240 Volts AC = 7.5 Amps AC
1,800 Watts ( running ) / 12 Volts DC = 150 Amps DC <<< WOW !!!

Your battery bank will be "dead" in about 30 minutes of pump operation.
Why did you select a 12 Volt DC Inverter vs a 24 Volt DC Inverter vs a 48 Volt DC Inverter?

Typically, when starting the well pump, the amps will surge, up to 5 times the running amps for a short period.
Will your DC-to-AC Inverter support this short burst of 38 Amps AC = 9,000 Watts ?
Will your DC wire and Battery Bank support this short burst of 750 Amps DC ?

Thanks for the informative answer.

I shouldn't have bought this inverter. Clearly, I didn't properly plan this out when I bought it. I guess I just figured the short length (1') of heavy gauge wire run from the battery bank to the inverter would handle the high amperage. It got good reviews and at $240 wasn't all that expensive if I needed to cut bait.

I never expected it to run the well pump sustained for 30 minutes for showering but just for light duty during power outages. The batteries are 12, 12V sealed lead acid 18Ah batteries currently in parallel.

I currently have a 5k/8.5k generator backup setup on a separate breaker with a poor man's transfer switch/interlock kit. We never measured the surge wattage of the well pump when we tested that, but if they surge that much then the cost of the kind of inverter I'm going to need to buy tells me it's time to reevaluate the scope of this project. Thanks.

[NEOH]

Yes, the amps surge on a Well Pump Motor is real.
That is what the CHART in message #2 is telling you.
And it is very difficult to measure the surge unless you have a "Peak Read & Hold" AC Amp Meter.
Email the Manufacturer and ask them if their 200W/4000W Inverter can actually output 9,000 Watt surge for 1/2 second?
or will the Circuit Breaker Trip ?
or will it Over Load Shut Down ?
or will it Brown-Out ?
or will it Release the Magic Smoke ?

Quantity 12 of 18 AH Batteries in parallel?
Well now, that is very interesting.
3 strings of 48 volts would be "less worse".

30 minutes total = shower + toilet flush + sink + ? and then the battery bank is dead.

Starting a 3/4 HP 240 Volt Water Pump Motor with a 12 volt battery is not easy or simple.
Some specialty water pumps actually have Soft-Start technology built-in to resolve this exact issue.

[MtnGuy]

Yes, the amps surge on a Well Pump Motor is real.
That is what the CHART in message #2 is telling you.
And it is very difficult to measure the surge unless you have a "Peak Read & Hold" AC Amp Meter.
Email the Manufacturer and ask them if their 200W/4000W Inverter can actually output 9,000 Watt surge for 1/2 second?
or will the Circuit Breaker Trip ?
or will it Over Load Shut Down ?
or will it Brown-Out ?
or will it Release the Magic Smoke ?

Quantity 12 of 18 AH Batteries in parallel?
Well now, that is very interesting.
3 strings of 48 volts would be "less worse".

30 minutes total = shower + toilet flush + sink + ? and then the battery bank is dead.

Starting a 3/4 HP 240 Volt Water Pump Motor with a 12 volt battery is not easy or simple.
Some specialty water pumps actually have Soft-Start technology built-in to resolve this exact issue.

Yeah, I'm just going to scrap the idea. I'll just run the gas gen for extended outages and get a 120V inverter to run solar for low drain stuff. Thanks.

[Mike90250]

Thanks. So then I could just wire the 240V single phase inverter to one of the 120V legs of the pump and whether the pump works or not would depend on whether the inverter and initial voltage hit in a 12V array could handle it, right? Do you think it's safe enough to try from the standpoint of not damaging the motor?

Sadly, you should not try to wire it up, because we don't have a common vocabulary of how to wire electrics.

The toy inverter will not be able to damage the pump.