Cable to motor is warm/hot at touch (60v 1500w)

[heavylildude]

Hi all,

I was recently purchase a 60v 1500w motor w/ 40A li-on battery.. Am now in the process of building a custom frame/bodywork.. The thing is yesterday, I was curiously test out the motor on and found out that the cable from the motor (hub motor) to the controller felt warm/hot at touch.. As well as the motor itself, I was just test it around 5 minutes or so (mount it to a regular bike, battery on bag, etc)

This is my first 'big volt/watt' engine, I was having mere 36v 250w setup, and the engine did getting hot after a while.. But never thought a bigger watt/volt is a lot hotter..

Is this normal? Or theres something wrong with the engine/cable/etc..

Thanks you!

 

[Sunder]

If it's just mildly warm to the touch, that's fairly normal.

1500W @ 60v = 25A. That doesn't sound like much, but is actually quite a large current, *if* your bar is to not let cables get warm. Technically, you can safely carry 25A on 18AWG with 200*C insulation, but it will be quite hot. You'd need to get down to about 8AWG if you didn't want a noticeable warmth, but that's getting really thick, and quite expensive.

Most likely, the manufacturers compromised with 12-14AWG, and just lets it get warm.

 

[heavylildude]

Ah I see.. Thanks for replying..

Its not realy that hot as in 'you cant touch it' hot, but indeed surprised me, since I never touch a hot cable before (its as hot as touching your car hood after running the engine a while, but not as hot as touching, say, motorcycle exhaust lol), youre right the insulation is not that thick though its definitely thicker than my previous puny motor..

Would you advise me wrap it over again, or is it actually not a problem in general (concern on melting etc)?

I have no intention for it has to be non-hot-to the touch whatsoever since its located on rear arm anyway..

Many thanks ahead!

 

[spinningmagnets]

If its warm, but not so hot that you can't hold your hand on it continuously, it's OK.

Would you advise me wrap it over again

No, any additional wrapping would act as insulation, and its good for the wire to be shedding heat.

 

[Gregory]

The copper wire is very good at transferring heat from other sources too.

It could be heat travelling out from the motor windings; or heat generated in a crappy connector, which would be worth checking.

 

[Sunder]

No, any additional wrapping would act as insulation, and its good for the wire to be shedding heat.

The copper wire is very good at transferring heat from other sources too.

Agree on both counts.

Don't wrap it, and if it's isolated heat (hotter on end of the wire than the other), there could be heat transfer somewhere too.

 

[dogman dan]

Look at your plugs, a weak connection there can cause an otherwise normal wire to melt. So if it's pretty dang warm, that's pretty normal. But any sign the insulation is melting is not.

 

[heavylildude]

Thank you for all input guys! Really appreciate it, will do post my custom bike project here when its done, thank you!