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1-800miner
08-13-2011, 10:19 AM
Years ago I saw a small sucker rod pump that was solar powered.It was used on a deep water well.It was a factory made rig,but I can't find anything on the net about it.

It had several panels directly wired to a dc. motor.
No batteries and what looked like a standard disconnect switch.I did not open it to see if there was any circuitry in it.If there was, it had to be small.

As I watched it,clouds would come across the sky and the pump would slow to a creep,then speed up when the cloud passed.
What type of motor and or circuitry did they use that prevented the motor from frying at low voltage?

I now have a sucker rod pump,several dc. motors and enough panels to power it.
I don't know how to wire it so it does not fry.

I want use it for the garden.I have a very high water table,will only be dealing with three to six feet of head.

I know there are simpler systems,I just like the looks of a grasshopper pump.

danlb
08-13-2011, 12:21 PM
As the light falls off, the total power available (volts AND amps) falls off. So even if slower RMS cause the coils to remaining energized longer, it is with greatly reduced wattage.

Dan

Rosco-P
08-13-2011, 11:19 PM
The man might not be alive today, but an advertiser and contributor to Home Power Magazine, was at the time the expert in solar well systems. I believe his name was Windy Danfoss. He'd have info on such a pump.

Paul Alciatore
08-14-2011, 02:26 AM
As the light falls off, the total power available (volts AND amps) falls off. So even if slower RMS cause the coils to remaining energized longer, it is with greatly reduced wattage.

Dan

For many DC motors this will work. If the motor has a lot of mass in relation to it's Wattage, it will PROBABLY be able to soak up and radiate away the power that is converted to heat. A large size wire in the windings would also help. You could look for motors that are rated for simple, variable Voltage speed control.

But if you have a motor that will not take the heat a fairly simple DC circuit should be able to turn the motor on and off at a safe Voltage level. A Zener diode in series with a base resistor going to a signal transistor to sense if the Voltage is high enough. The Zeener Voltage of the diode would be about 0.7 Volts less than the desired operating Voltage. A second signal transistor to invert the output of the first. Finally the output of the second small transistor would control a power transistor or FET which is in series with the motor. Three transistors, a Zeener diode, and several resistors. You could do it with ICs too. A 555 timer IC could be rigged to sense the Voltage and drive the power transistor or FET. Or if the motor is small enough, the 555 could drive it directly. Again only a handfull of parts. Either of these circuits could be built on a circuit board of about 1 sq inch area.

Paul Alciatore
08-14-2011, 02:28 AM
As the light falls off, the total power available (volts AND amps) falls off. So even if slower RMS cause the coils to remaining energized longer, it is with greatly reduced wattage.

Dan

For many DC motors this will work. If the motor has a lot of mass in relation to it's Wattage, it will PROBABLY be able to soak up and radiate away the power that is converted to heat. A large size wire in the windings would also help. You could look for motors that are rated for simple, variable Voltage speed control.

But if you have a motor that will not take the heat a fairly simple DC circuit should be able to turn the motor on and off at a safe Voltage level. A Zener diode in series with a base resistor going to a signal transistor to sense if the Voltage is high enough. The Zeener Voltage of the diode would be about 0.7 Volts less than the desired operating Voltage. A second signal transistor to invert the output of the first. Finally the output of the second small transistor would control a power transistor or FET which is in series with the motor. Three transistors, a Zeener diode, and several resistors. You could do it with ICs too. A 555 timer IC could be rigged to sense the Voltage and drive the power transistor or FET. Or if the motor is small enough, the 555 could drive it directly. Again only a handfull of parts. Either of these circuits could be built on a circuit board of about 1 sq inch area.

If you could provide more details I could do a schematic with specific parts.