Instructables

Need To AutoStart 1.5hp Motor When Inverter Battery Drops To 11Volts

My Set Up:

Car Alternator: 12V / 30Amps
Motor: 1.5HP / Single Phase / 220 V / 8.5 Amp / 1420 RPM
Battery: 12 V / 185AH x 3
Inverter: 2KV
Mains AC: 220 volts / 50Hz

1.5HP motor attached with the 220 volts main supply, is used to run the Car Alternator; the batteries are charged by the alternator. Inverter is used to convert DC to 220v AC to power utilities and computers.

I need your advise,

to develop a system to auto-start the 1.5HP motor to run the alternator when battery voltage drops to 11 volts and stop the 1.5HP motor when the battery is charged fully to 13.80 volts.


Thanks in advance.
Regards

Look for a battery indicator circuit. You'll find many that will work with 12V and can be adjusted for the appropriate low voltage indication and light an LED when it's low. Now the base of a transistor can be connected to the LED with the collector of the transistor connected to the positive lead of the battery and the emitter connected to the coil of a relay. The other lead of the relay's coil will connect to ground. Now the relay need to connect to your motor.

So the transistor needs to activate off the voltage from the battery indicator and handle the 12V needed to activate the relay. The relay needs to have a 12V coil and handle mains power. So when the battery indicator shows a low battery and turns on the red LED it will allow the motor to run. Then when the battery is fully charged the low battery indicator will turn off turning off the motor.

I would like to note that using a motor to run an alternator to charge a bank of batteries if very in efficient. You're better off using a charger. It will be faster, can include a charge controller on it to only charge them when needed and will be much more efficient.
psb1967 (author)  mpilchfamily1 year ago
Hello Mpilch,

## I would like to note that using a motor to run an alternator to charge a bank of batteries if very in efficient.
I will surely keep this important point in mind.

# Look for a battery indicator circuit
I will start looking for one and give it a try with your setup.

Thanks/Regards
rickharris1 year ago
Has the motor got an electric start on it?
psb1967 (author)  rickharris1 year ago
Hello Rick,

The motor has a start capacitor.