Troubleshooting Low Pump Discharge: Tips to Boost Speed and Output

[prasan_y2k]

I have a 12v DC (rotary vane type) pump that is connected to a 12v auxillary battery. The battery is 12vDC 70Ah and it charges itself with the truck's alternator, which is 12 volts, 35 amps. the pump is 1/4 hp, and it draws 20 amps max. The problem is, the discharge output of the pump is very low(8-10lpm), whereas the pump is designed to have a max discharge of upto 57lpm.
What is the reason of low discharge?
Is there any way to increase the speed of the pump so that the discharge rate is increased?

 

[anorlunda]

Most likely, the low performance is because of excessive voltage drop in the wire. Too thin wires, combined with too long wires. Here is a table you can use to size wire so that the voltage drop is never more than 3%. Look up 20 amps, your required length, and the table gives the required wire gauge.