Why does a electric motor get hot?

[Bala]

this is nothing to do with solar but i hope you will help, i am a mechanic on an island and have about 20 staff in my workshop, these guys and one girl who is my welding ta, really do live in grass hut and have no electricity apart from some tiny solar, or running water. Although it saddens me as some pay a fortune for very small panels and as its wet tropics they dont do much to charge their batteries which are mostly old start batteries from the workshop.

Again today an engine would not start and I had to intervene to stop them from continuing to wind the engine over as I have spent a lot on starter motors lately simply because an engine would not go and they kept winding until the starter would not go, so i can tell them that they must not wind over to much and I can throw volts,amps, formulas around and will show them a continuous run motor with fins and a fan versus a starter motor that is meant for short bursts of use,

how would you most simply explain why a motor gets hot.

[Sunking]

In this case you already did. Starter motors are not designed to run continuously. They have no cooling fans or means to remove excess heat.

[Bala]

But why is the heat there?

[TnAndy]

Lot of really excited electrons.

[Sunking]

But why is the heat there?

Because you are dissipating a lot of energy (power or heat) in a small confined space in a very short period of time. If you have a battery rated at 500 CCA you are discharging 7 volts x 500 amps = 3500 watts.

[Bala]

Because you are dissipating a lot of energy

I got what I wanted from this line,

Remember i am looking for a simple explanation, what I will use is something along the lines of,

When we (people) work we get hot, from creating/using power/energy if we have no wind or water to cool us we get to hot and die , a diesel or petrol motor gets hot as it creates and uses power/energy so has water and or wind to cool it, constant run electric motors have wind to cool them, starter motor dont have any wind or water cooling.

Thanks

[Sunking]

I got what I wanted from this line,

Well FWIW that does not really apply because the human body or an engine is designed to remove and get rid of the heat within limits. A starter motor is not designed for that type of use.

[Bala]

Well FWIW that does not really apply because the human body or an engine is designed to remove and get rid of the heat within limits. A starter motor is not designed for that type of use.

A starter motor is designed to get rid of its heat within its limits just the same as the others, what I need to get across it that starter motors dont have the ability to get rid of heat quickly/constantly thats why if they are used to much, they burn out, and by used to much that is NOT MUCH.

These guys will wind 24V, 5,5kw starter with 2 x n120 batteries until the engine either goes or the starter or battery goes, they have no concept of what is happening, one of my mechanics is trade qualified worked in mines and still burnt out a starter on a tractor trying to get it going when it was never going to start as they had not changed the fuel filters and the injector pump had seized, I had to stop another qualified mechanic yesterday doing the same on a quad motor bike.

the just keep winding