DC Motor Charging

Question

I've got a 12v, 8w Dc motor. Can I power it up with 12v,1amp AC-DC charger?

Can I use 12v charger with any Amp charger?

Note: It works fine with 6x1.5v AA batteries.

Answer 1

A motor takes about 10x normal current on startup depending on DCR resistance with an ohm-meter. So a motor at rated load of 8W/12V= 2/3A thus for starting x10 or ~ 6.6A so a 1A charger will start with 15% of rated starting torque.

Other info

The most power is the combination battery + charger just like a car but your charger might overheat if not designed for this load.

A Battery cell is equivalent to a minimum chemical cell voltage with an UltraCap of 10kF order of magnitude and ESR in series. The ESR (Effective Series R) rises exponentially below 5~10% SoC.(State of Charge)

A Battery Charger is somewhat the opposite. It is a high impedance Constant Current (CC) up to about 85~90% SoC for the battery as it charges up to the terminal CV constant charge Voltage where the charger is now low impedance but the battery current drops until 5~10% of CC = cutoff threshold is reached.

Depending on how smart the charger is at detecting the battery initial and final conditions may/may not behave as you wish for a motor drive.

Since a motor force/load determines the acceleration rate, you can expect this to give a controlled rate. We expect you mean an automotive 12V motor that might tolerate 14.2V and not a motor rated for less voltage due to heat rise.

So your performance will be slower for starting but faster for final RPM/V if the charger goes to 14.2V vs a 12V regulated supply.

Without inductive kickback protection, beware that an abrupt turn off of motor might damage the charger with overvoltage. Thus it is not wise to do what you suggest.

Yet including a suitable 12V battery string with the correct voltage rating connected to the charger will reduce the risk and improve the power source.