I have a 12v DC 36w high volume low pressure inflator, and I'm trying to power it with 18650 batteries. The batteries when fully charged will provide ~12v when used as a pack of 3. The inflator is working fine when connected to its own PSU.
When I connect the battery pack up to the inflator and turn on switch, the motor fails to start. If I leave the motor switch on, and touch wires, the motor gives a slight twitch, then nothing. If I kind of rub the wires over the terminals of the battery, the twitches build over a second or two, and the motor can start. If I then fix the wires in place while it's running, the motor continues to work and the units functions.
Is this because the initial starting current required by the motor is more than the battery pack can provide?
If I put my multimeter in parallel with the power termimals while in current mode with the motor running as described above, it registers the current drawn as 0.6A, and the motor slows down. If I disconnect the multimeter, the motor stops. The interesting thing is, if I reconnect the multimeter to the circuit while the motor is powered up but not starting, it causes the motor to start working at this lower speed. So the motor can in fact start from the batteries with a certain circuit in place, albeit at a lower speed.
Is this because the initial current required is less in this arrangement, and within what the batteries can supply? If this was the case I would expect that once the motor is running at this lower speed, removing the multimeter would mean it would result in the motor ramping up to full speed because less initial current was needed.
What to do? Adding a variable resistor in parallel to emulate the multimeter came to mind. How is it done properly? Do I need a capacitor to discharge into the motor to get it going?
Thanks for taking the time to read.
When I connect the battery pack up to the inflator and turn on switch, the motor fails to start. If I leave the motor switch on, and touch wires, the motor gives a slight twitch, then nothing. If I kind of rub the wires over the terminals of the battery, the twitches build over a second or two, and the motor can start. If I then fix the wires in place while it's running, the motor continues to work and the units functions.
Is this because the initial starting current required by the motor is more than the battery pack can provide?
If I put my multimeter in parallel with the power termimals while in current mode with the motor running as described above, it registers the current drawn as 0.6A, and the motor slows down. If I disconnect the multimeter, the motor stops. The interesting thing is, if I reconnect the multimeter to the circuit while the motor is powered up but not starting, it causes the motor to start working at this lower speed. So the motor can in fact start from the batteries with a certain circuit in place, albeit at a lower speed.
Is this because the initial current required is less in this arrangement, and within what the batteries can supply? If this was the case I would expect that once the motor is running at this lower speed, removing the multimeter would mean it would result in the motor ramping up to full speed because less initial current was needed.
What to do? Adding a variable resistor in parallel to emulate the multimeter came to mind. How is it done properly? Do I need a capacitor to discharge into the motor to get it going?
Thanks for taking the time to read.