# Water from well pump



## Stvreilly (Apr 25, 2016)

Excuse my ignorance. i want to put together a basic, solar powered battery bank to pull water out of my well. I own a Peak 3000 watt continuous inverter. My well is 50 ft deep and has a 1/2 hp motor at the bottom. I believe this is a 2100 watt start and 1000 running. I was thinking of putting together 2 Trojan 105 re batteries totaling 12 watts. Is this possible to pull water a few times a day. If so, how many panels can I put on these batteries ? Is 600 correct? If so I need a 50 amp charge controller correct? Does this sound right and would it be enough??? Any advice would be appreciated.


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## Chiefster23 (Feb 5, 2016)

Most electric motors draw 5 to 7 times running amps upon startup. So your startup load is probably closer to 7000 watts. But this is a transient surge load. Your inverter may be able to stand that. Probably not. Check with the manufacturer. As for battery capacity, best way to check is to put a meter on it for a day to keep track of power usage. Then there is lots of online info to convert kW to amp-hrs so you can properly size your battery bank. I use a 'kill a watt' meter I bought on amazon.com. Call the people at 'Grape Solar'. Very helpful and their products are sold thru Home Depot with free shipping.


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## hawgrider (Oct 24, 2014)

Chiefster23 said:


> Most electric motors draw 5 to 7 times running amps upon startup. So your startup load is probably closer to 7000 watts. But this is a transient surge load. Your inverter may be able to stand that. Probably not. Check with the manufacturer. As for battery capacity, best way to check is to put a meter on it for a day to keep track of power usage. Then there is lots of online info to convert kW to amp-hrs so you can properly size your battery bank. I use a 'kill a watt' meter I bought on amazon.com. Call the people at 'Grape Solar'. Very helpful and their products are sold thru Home Depot with free shipping.


Starting amps of electric motors is 2.5 times greater than running amps of said motor at start up. NOT 5 to 7 times higher


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## Stvreilly (Apr 25, 2016)

Thanks guys, I already own the inverter. Not any other part. Just ordered a kilowatt meter, so that should help. Can anyone address the part I mentioned about only being able to put 600 watts of panels on a 12 V system? I don't have a problem investing to grow the system in the future. I just want to sleep at night knowing I can pull water out of the ground in the near future, if I have to.


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## Chipper (Dec 22, 2012)

Could just use a hand pump?? Like people have used for many years before electricity.


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## 8301 (Nov 29, 2014)

HogRider is correct on the starting amperage bump.

A 1/2hp well pump will draw about 500 watts when running and roughly a 1400 watt starting surge (3-5 seconds). Assuming your inverter puts out the same voltage as the well pump (what voltage is the well pump?) it can work but since you have a less expensive modified sine inverter it can be a little rough on the pump motor and cause the pump motor to draw a little additional power.

Your two batteries have a 225 amp/hr reserve at the 20/hr. discharge rate so they have enough energy to run your 1/2 hp pump for up to 2 hours straight and not go below 50% DOD (depth of discharge) although a long drain (over 20 minutes) may draw the power fast enough from the batteries to damage them so just don't water the garden for several hours straight with only 2 batteries.

You want between 350 and 500 watts worth of panels to avoid charging the batteries too fast and overheating them (I'd go for close to 500 watts). If you're using a less expensive PMW charge controller get "12v" panels which means they put out around 18v open voltage. A 35 amp charge controller is as small as you want to go with 500 watts in panels. If you add more batteries then add more panels. 

note: If your pump really is pulling 1000 watts running and a 2100 watt start surge you have a 3/4 or 1 hp pump, not the 1/2hp pump you think you have.
Also, while you should be ok with just 2 batteries if the initial surge of power the inverter draws when the pump starts up drops the battery voltage below 10.5v the inverter may shut down and you may need to add 2 more batteries to spread out the initial load. I think you'll be fine since those are some heavy duty batteries but suddenly drawing 200 amps (2300 watts) will make the battery voltage drop and you're only spreading that load out over 2 batteries. Must inverters wait a few seconds before shutting down from low battery voltage to help keep them from tripping with motor starts.


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## Stvreilly (Apr 25, 2016)

Thank you. I was also considering a hand pump. Ultimately, I still want to learn how to build a small solar system.


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