Can series connected motor be run straight from batteries?

what is the application?

The application is undecided as yet. They want to use it for a rudimentary winching application possibly.

The question they want is : If the 72 motor were connected straight to the batteries is it going to runaway, burn up, or other bad news. Or would it simply go to top speed and stay there drawing no more than the 72 x 82 amp= 5.9kw power. Batteries can discharge at 72 volts up to 800 amps if shorted so its factor or 10x unknown area in their minds. Some think a motor can never draw more than its rating (approximately) but that is the question.

the BEST way to find out is to try it. if lights start getting dim or smoke starts coming out of it then yank the power, otherwise let it go and measure current, rpms, temp. nobody can give you answers as good as the ones you observe first hand.

Yes, you can run it providing both coils (armature and field/stator) have the same wire crossections, usually the same (flat) shape.

All starter motors are serial connected and polarity unconscious, (run the same way regardless of polarity).

The speed control of universal motors, they say, is poor but acceptable for many practical purposes, especially for yours/theirs.

The problem will be during the staring phase, Where the current will be too high for the brush of the motor (no speed, no counter electromotive force, only the winding resistor so very low value near short-circuit) .

On one of my application we used a DC motor of 7.5kW (110V 82A) and we have to limit the starting current under 240A (current limit of the brush) by adding starting resistors.

We have a 3 steps starting for this application. The in line resistors will be removed by a timer after starting; this will be the cheaper way to start this motor.

BR

Best Regards

A DC series motor will run away if run without a load; speeding up until it self-destructs. Bear this is mind if you are performing any run tests.