Electric motor overheating - Fuel Economy, Hypermiling, EcoModding News and Forum

Amro · 07-20-2009, 05:55 PM

Hi,

I'm converting a three wheeled freight moped to electric drive but I'm running in to an unforseen problem. The quite sturdy (and ancient) motor is overheating.

Yesterday I was doing a test drive out in the woods (using the bicyclelanes mostly) when I noticed smoke coming from the motor. The engine casing was really hot !

I was testing the new trojan T105's I got cheaply (still doubting it was a good buy) and the new cables I made. That was okay, the cables didn't get hot (like a few days ago, melted one

)

I just don't understand where the heat come's from. I'm using a bosch brushed motor dc 1,8 kw 150 amp 24 volt and a sevcon pmw controller 24 Volt / 200 amp and off course 4x6v T-105

On this page you'll find some old pic's from some months ago: Bakbrommer :: View topic - Foto's electro bak

I've been thinking it might be the ratio of the gear/cogs (I'm not sure of the proper word) because that's 16 front (motor) and 41 back (rearwheel).

I think my question is if an electric motor can't get to it's max. rpm (i.e. 2000 in this case) does it keep on trying? And sucking up amps which cause al the heat ?

TIA

Amro

ConnClark · 07-22-2009, 02:41 PM

Is your voltage level dropping much when the motor is running? (Electric motors get hot when operated at too low of a voltage)

Bicycle Bob · 07-23-2009, 12:40 AM

Yes, when a simple DC motor is overloaded for torque, it heats up. It gets more current and less cooling. Check your amperage?

Ryland · 07-23-2009, 10:01 AM

what is the motor out of? how long is it designed to run for? if it was a starter motor or something of that sort that was designed to run for 15 seconds then I would say that you picked the wrong motor.

Amro · 07-23-2009, 04:31 PM

Hi, thanks for thinking with me.

I only have an analogue amp gauge. That goes till 150 amps. I've read that those T105's can sustain 300 amps for 15 min's and I know the PMW-controller switches itself out of the loop after being asked for the max. amp. for more then 2 or 3 seconds.

The voltage drops to 21 volts when driving away and then when cruising at max. speed creeps back up again to 23 volts.

The motor is from a Spijkstaal electric lorrypuller (like a locomotive but smaller with out the rails) and could originally move 4000 kg's. So, it's made to run all day but at slower speeds (15 km max.)

The originall ratio was 11/60 with the 60 tooth sprocket/cog(?) on a 12 inch wheel.
You must excuse me, my technical english is not that good

Does the ampmeter go between the controller and the ground of the motor ?

Bicycle Bob · 07-24-2009, 12:23 AM

The ampmeter could go between the contoller and the motor, or between the motor and the ground.

Perhaps your motor insulation is failing. Once the magic smoke starts to get out of any electrical device, it is like seeing water trickling through a dike - there might be a lot more of it soon.