Running a Well Pump off Batteries - How much power do I need? (Part 1)

[@cutweldngrind]

I've been running 24v pumps for over 2 years but they only put out about 6gpm max. I'm looking into a 110v pump to test on my 2000w inverter now.

[@barrellcooper6490]

Thanks for these videos. I dealing with some of the same issues, so seeing your hands in approach is very helpful. Pet peeve of mine diy people that state 1hp = 748 W, and/or looking at a pump reading plate and saying Amps x Volts = Watts. First the horsepower conversion. This is like saying 1 inch = 2.54cm. it's just a conversion. The 1hp rating on pump is not the same as it's per consumption, and neither is saying the voltage x the nameplate amps is is power consumption. The 1hp is the pump's nominal size. It's based how much per it needs from the electric motor there's a lot more to it the even this. But 1hp is the nominal size. Not the power consumption. So trying to determine consumption applying a numeric conversion factor is a gross lack of understanding. Also volts x amps = Watts does not apply with inductive loads like motors. Instead it you did think of it as VA or VoltAmps this is also called apparent power, and this has to do with power factor. But it is probably the important number for sizing the inverter, but not the battery storage needs as the actual power consumption is less than the VA figure.

[@tibork3845]

So how do I calculate what kind of inverter I would need? I have a 230V 4.8 amp (S.F. Max Amp 5.9) 1/2 HP motor, fuse in panel is a 2x15 AMP.

[@HousewifeInTheWoods]

Thanks so much for this. We've been off grid for 5 years and the well pump has been an issue.... thos really helps.

[@raymondergarcia]

Awesome video, appreciate you putting together. Exactly what I was hoping to find in sizing my inverter for my well pump.

[@drsolar]

Your videos are very detailed. I have a 1 hp pump and I run it on my 3 kva Victron Phoenix with no problems. I am sure you will be fine with a 3kva inverter for your pump

[@jacoblopez6365]

Interesting because after a google search I read this - "For a 4 KW plant, you can take about 8 batteries of 120 Ah capacity or 150 Ah capacity." That's a pretty stout system isn't it?

[@drsolar]

@@jacoblopez6365 if you are off the grid you have way to much panel relative to your storage.

[@civstu]

Cool shirt, fellow alumnus! Good job putting all that theory into practice! Class of '07, BSEE.

[@Altenurgy]

Good job! Power vs. Energy can be challenge. Nice methodical approach and you didn't get bogged down in the sig figs swamp. We've started specifying constant pressure well pumps for our off grid customers because there surge is so much lower. Actually they don't have any surge because they slowly ramp up. In some cases the savings from the smaller inverter goes a long ways to paying the well pump. One thing to be careful about is that a 2,500 watt "truck stop" inverter cannot be used for well pump sort of loads because they cannot surge at all and of course they are 120v only. Take care!

[@drsolar]

I have clients running a well pump off the SW 2524 and it has been flawless

[@summetj]

Yes, the SE 4024 inverter would be my primary choice if I had a $2,000 budget... (I mention the 4024 inverter in my 3rd video: kzbin.info/www/bejne/pYO6YnyPhMyhsJI )

[@phaedrus6198]

What a great video series! You have covered in detail all the aspects of an economical diy system which I have spent a lot of time trying to piece together from so many different sources on the web. Someday it would be great if you would add solar charging to your system! Thanks

[@paulmaxwell8851]

Start current can be three times, even three and a half times the run current, easily. My 1/2 hp well pump can barely start on my 2.5 kW generator, and my 1.5 hp well pump needs a 6 kW generator to start and run. That's my experience. Good video!

[@summetj]

That sounds about right 👍

[@RodneySolarCircuits]

awesome video, exactly what I was looking for. My pump switch was stuck off one morning and I was not able to get drinking water or flush the toilet. Thats all it took for me to figure a way to fix it! looking at going solar as well.

[@Madcat41]

This is exactly the information I was looking for.

[@lanedexter6303]

A horsepower is 746 watts, but no motor is 100% efficient. Allow a kilowatt or so. My well pump is 240 on a 20A circuit, and it’s only 1/2 hp. But allow plenty for starting inrush (surge) on compressors and pumps (and anything else that’s likely to start under load). When in doubt, go big on the inverter and battery.

[@Mr25thfret]

Not sure if this fits your situation, but, you can drastically reduce the battery power needed by front ending a maxwell Supercapacitor pack for the starting of the pump. This will also extend the life of your battery.

[@summetj]

Yes, having a supercapacitor pack in-line would allow the inverter to draw more amps for the pump startup, but it wasn't in the current budget.

[@Mr25thfret]

@@summetj Understood. What size battery (volts and Amp hours) did you end up with for this project? This is the part I still have yet to nail down.

[@summetj]

@@Mr25thfret You'll want to see the 4th video in the series: kzbin.info/www/bejne/nHrOZKmXoc6CldU Its about 2-3kWh of Nissan Leaf modules (6 modules in a 2p3s setup for 24 volts nominal).

[@Mr25thfret]

@@summetj Thanks Jay! I'll check it out. Cheers!

[@cetyl2626]

The HP is the power output from the motor. The input to the motor is what you want. Motors are not 100% efficient, a lot gets turned into heat. Especially older motors. So your measurement makes sense.. although 30% efficient seems to low (75% would be more like it)

[@shermdog6969]

Exactly what I wanted to know

[@devinmartin2031]

My dude is smart thanks for teaching me something today Broh! Haha

[@brentjohnson6654]

New sub here. This is exactly what I am looking into. We have a pump in rural texas. I am going to take my clamp meter to my pump house and do just what you have done. I am concerned about the surge or starting this up.

[@summetj]

You need a relatively large inverter to start a well pump, unless it's one of the newer soft start or constant pressure models.

[@brentjohnson6654]

@@summetj yes I am familiar with the concept of a soft start. I have seen where some have run air conditioners on an inverter by adding a soft start (basically sounds like a capacitor to handle the startup surge). Now the specifics on the other hand are what I need to figure out. Thanks for your quick response.

[@william38022]

I have a Digital inverter grundFoss deep well self priming 120 volt well pump,,, I would like to try figure out something like this also.

[@summetj]

That 120 volt pump would probably not require as large of an inverter as I needed for my "hard start" 240 volt pump.

[@stephenmoore7701]

Great video! Did you go with 12v batteries?

[@summetj]

I used a 24 volt system, you can see the details by watching the rest of the videos in the playlist

[@rosemariebredahl9519]

Re 1 HP: Was your measurement when you turned on your pump the surge amount (as in halving it would approximate sustained level, vs doubling it to guestimate surge)?

[@summetj]

My amp measurement was after the initial surge...so it was the sustained level.

[@jacobbradley4865]

I think a big issue is In-rush Current, I've seen well pumps fed by a 240v 20A circuit, draw 40amps during start up.

[@summetj]

Yes, unless you have a soft start / inverter controlled pump, you definitely need to size your system to handle the startup surge.

[@jacobbradley4865]

@@summetj That makes sense, 👍🏻

[@jacoblopez6365]

@@summetj that can come from battery storage though right?

[@summetj]

@@jacoblopez6365 Yes as long as the battery is large enough and your inverter can also handle the surge.

[@edbouhl3100]

Was a smaller, more efficient, or less demanding pump an option?

[@summetj]

Well pump is under concrete and an eve...so I hope we never have to replace it ;>

[@GY6SCOOTERCHAT]

How much was the powersight analyzer?

[@summetj]

More than you want to spend.... luckily I picked it up surplus.

[@nickrhee7178]

Can you use inrush current limiter or a soft starter to reduce the initial current significantly lower? I am interested in making a simple soft starter using inrush current limiter for example Ametherm's Inrush Current Limiter. Soft starting will allow me to use much smaller inverter to run my 240v 1HP well pump. There are soft stating well pumps in the market.

[@summetj]

My pump has a "start capacitor" but does not have any other more actively managed inrush current limiter or VFD. Anything you can do to reduce the startup surge is good, but to run a 1 HP motor you are going to need a relatively beefy inverter.

[@nickrhee7178]

@@summetj Thanks for your reply. Can you tell me more about your 'start capacitor'? Did you design it? I have a single phase 3000watt 120vAC output all in one inverter- solar panel charge controller, automatic transfer switch (10 msec), UPS functionality with three EG4 server rack 5KW 48V batteries - total 15KW. So I am looking into inverter options to run my well pump. One option is to add another same inverter to generate 240V AC - 'split phase'. Or I could buy expensive two 3000w Victron Multiplus II, Schieder Connex SW4048/XW-Pro 120/240 AC, that are ehigher quality with low idle current. Cheaper option is low frequency Grwowatt 6Kw 120/240v all in all inverter with high idle current. I just want to make sure that I go with an option that will be able to run my well pump.

[@summetj]

@@nickrhee7178 The start capacitor is the standard one that comes with most well pumps air conditioning condensers etc. It does its best to get the motor running but it's not really a full in rush limiter or VFD. Your well pump probably already has one.

[@josephpulse2537]

you are looking at a pump the hp is the motor rating not the whole pump. The pump has to move water and this is why the whole is more than 750 watts.

[@jacoblopez6365]

If you fell short, would the pump run slower or stop running all together?

[@summetj]

If the surge capacity of your inverter was too low, the pump would not start (or your inverter would be damaged). If your battery capacity was too low to provide enough amps (the voltage would sag) it may cause damage to your inverter and would also fail to start the pump.

[@riverbankfisher]

I'm curious as to why your mains electricity supply is the European 240 volts AC, since you are located in the USA where the mains electrical power is 110 volts AC. Are there some areas of the USA that use 220/240 volts AC ?

[@summetj]

The US has split-phase 240 volt AC (not-neutral-hot). Most consumer appliances are 120 volts which use only half (hot-neutral) to get 120 volts. However, high wattage (permanent) appliances such as range, AC unit, water heaters, clothes dryers, EVSEs and well pumps use (hot-hot) to get access to the full 240 volts so that their wiring can stay a reasonable size while still transferring the large wattage they draw. So if you want to power one of these large items, you need a 240 volt split phase inverter (see parts 3 and 6 of this playlist).

[@riverbankfisher]

@@summetj Ah, I see. Thanks for this clarification.

[@bamaslamma1003]

There's no neutral in a straight 240 volt circuit, just two hots and a ground.

[@summetj]

That is true, but in the US most 240 volt (split phase) circuits include the neutral, such as with a NEMA 14-50 outlet, and most modern range and dryer outlets.

[@jp2159642587]

That is good information but very complicated. The alternative for me is to buy a generator I just plug it in and then I have some water.

[@summetj]

Yes, that is less expensive and easier. Just make sure the generator is far enough away from your house that no fumes can enter (windows, vents, etc...).

[@failingdisciple938]

Has anyone tried a VFD, variable frequency drive? It meters the power to the pump motor lowering the startup power needs and it can be adjusted to lower the motor rpm’s requiring less running amps. The well pump doesn’t necessarily need to run at full RPM to fill the pressure tank

[@summetj]

Yes, also known as "slow start" technology in the well pump industry. They exist and do reduce/eliminate the startup surge, but cost more than regular pump controllers, and are not stocked by all installers.

[@failingdisciple938]

@@summetj appreciate that! Bought one but not if it’s supposed to go before or after the pump controller

[@mycats7321]

This is very interesting. I have a Gould's pump that has 1HP 115/230v. It's hooked to a 40amp breaker. I'm trying to find out if I can get solar panels powerful enough to run it. Or at least find a good surge protector because the thunderstorms keep causing power surges that fry the wire to the pressure switch (and last time fried the actual pressure switch). I have a setup where my pump is in a small shed outside so it isn't well insulated. It doesn't have any of the fancy boxes & stuff. It's two pumps (one has pulley wheels and uses pressure to pull water up into the cistern). It is wired to a D-Box for the float lever on top of the cistern that splits off to the jet pump that pumps water out of the cistern. So, I would need something to power both pumps (I still need to find out how much power the other pump uses). Btw, you don't have to put water in your toilet tank to flush. You dump it directly in to the bowl & it will force the toilet to flush. It uses less water than filling the tank. I've had to do this a LOT because my power goes out frequently in storms. Curse of an old house from the 40s with crappy wiring.

[@summetj]

You did not specify if the pump was wired at 120 or 240 (115/230). Most pumps would be wired at 240 by default, but a 40A breaker at 240v is overkill for a 1 HP pump, so maybe it is wired for 120 volts. 40A at 120 v = 4,800 watts. 40A at 240 v is 9,600 watts. If it is a 120v pump, you can find a lot of 120v inverters. I'd recommend looking for a 5,000-8,000 watt one to be able to handle the startup surge. If they are 240v pumps, you will need a 240v inverter. You would need a battery bank large enough to provide for the startup surge. However, you may find that you only need a few solar panels to re-charge the batteries depending upon the duty cycle of your pump(s). If they only run for 15 minutes out of the day, the total power usage would be small (but have high surge requirements for when the pumps start up). If you can somehow make it so that only one pump runs at a time (disable the cistern pump when the jet pump is running, for example) that would reduce the size of the inverter you would need.

[@The_Defiant_One]

*Don't touch!*

[@JourneyOnLife]

My 1hp well pump uses 8 amps

[@thebubba1]

How is it 10 amps at 240 x 2 when youre only measuring one leg which is 120 .......meaning 240 is two legs of 120 so if your reading 10 amps on one of 2 legs you need only double your reading (120v X 10 A X 2= 2400watts) to get the wattage......in this case 2400 watts.....startup guess would be around 2x maybe little more but only for a second

[@summetj]

The amp meter only measures amps. I measured the volts separately (my house is very close to 240 volts) with a multi-meter. Because the well pump uses both sides of the split-phase 240v power, the amp draw on each side is equivalent.

[@thebubba1]

Exactly..... you clamped the meter on one side ......one leg of 2.....which is half the supply ...that one wire you clamped only has 120volts on it @ 10 amps .....which would equate to 1200 watts.EACH leg....circuits A+B .....A=120v @10 amps + B=120v 10amps = 240v @. 10 amps ...... Not 240v at 20 amps.....if youre using a voltmeter and hooking up the red on The A side and the black on the b side you will absolutely read 240 but your amp test was only reading 1 leg.......correction....it draws 2200 watts when its on ....just checked

[@summetj]

@@thebubba1 yes, I went through that calculation in my video.

[@thebubba1]

Theres zero chance a 1 horsepower well pump draws almost 5k watts....i jave a 1 hp myself with a permanently mounted amp/voltmeter and it draws about 2800 watts.but ive also got about 600 feet of 14 gauge wire feeding it so the amo draw will be alittle higher

[@thebubba1]

@@summetj ....how did you come up with almost 5000 watts?

[@AndrewKvochick]

Your videos gave me a lot to think about. But I'm a total electrical noob and I'm not even sure if it's OK to put an adapter on my pump plug. I have questions, that I detailed here: diy.stackexchange.com/questions/200987/battery-backup-for-240v-usa-water-well/200988 And I second the "solar charging" request from another commenter.

[@buzzzkill9183]

DON'T WATCH THIS SERIES OF VIDEOS ,HE NEVER SHOWS THE WELL PUMP WORKING. the title says running a well pump blah bla and it never happens.

[@summetj]

You need to re-watch video 7: kzbin.info/www/bejne/i3zOin2cgNiAmc0