I JUST DON'T GET IT

[lookinc]

I have a electric pump for pumping water it is 110 volt 7.7 amp can I run this off of a 12 battery using a 300w inverter and does anyone have any idea how long it would last ? I know it all depends on the batteries but say a good deep cycle truck or a boat battery. Also say I had a 200w solar panel would it run the motor if it was getting full sun? I know these are simple questions for most of you but the electricity stuff just baffles me.

Thanks

Ben

[ghurd]

Amps x Volts = Watts.  847W running.

And motors, especially pumps, have huge surge currents.  Meaning the amps can be 10 times higher when first turned on.

If it is 10X, then 8470W.

If the inverter is 85% efficient, 847W / 0.85 = 1000W out of the battery.

Amps x Volts = Watts, meaning Watts / Volts = Amps, meaning 83A.

A large car sized (G27) true deep cycle battery is rated about 110AH at the 20H rate, meaning it will run it about an hour.  That would be severe abuse to the battery causing it to have a very short life.

A 200W 12V nominal panel makes about 11.8A of 12V power at high noon in perfect conditions.

The pump needs 83A of 12V power.

Might look into a DC pump.  They tend to be more efficient.

This is a fan, but the principles are the same,

http://www.fieldlines.com/story/2007/3/10/23942/1876

G-

[tanner0441]

Hi

I don't know how much water you need to pump, but for a remote location I would go for 12 or 24Volts.  Not only do you have a very high starting current from your 110V pump you have losses in the inverter.

One or two 12 Volt pumps could be wired so if you were just topping up a holding tank you could run one and fill it over a longer time. If you had a high demand run both pumps at the same time and fill the tank more quickly, or dirrect feed.. If you ran positive displacement pumps you would not even need to worry about back check vales to prevent water back feeding through the idle pump.

Something like the Sureflow pumps used on RVs and Marine applications, they will supply 40psi, 6 to 8 (UK)Galls a minute and only pull 4.5Amps.

(UK Gall 4.546 Ltrs US Gall 3.9Ltrs

Hope this helps

Brian.