Why are the wires from the ESC to motor hot?

[sciesielka]

I am trying to figure out why the ESC-to-motor wires are so hot when everything else is only warm. By warm, I mean the batteries are right around 100F, motor end-bell is about 110F (the motor shaft at the end-bell is 125F) and the ESC is 90F. I'm running in the summer with 85 to 90F air temps. Surface water temp, near shore where I can measure it, is 80F. The motor wires I can barely touch. Nothing has desoldered ... yet and the ESC-to-motor connectors are tight.

ESC: OSE Raider 150A with timing at 15*
Motor: Leopard 4082 1250KV Y-wind w/water jacket and I just used the connectors that came on both from OSE.
Batteries: RoaringTop 3s 55C, 6500mAh wired together for 6S
Prop: Octura x447 sharpened and balanced (bought it that way from OSE)
Boat: Joysway Invincible Razor, 37" long x 10" wide, almost 8lbs with batteries

In the spring, when I first built and ran the boat and the air and water temps were lower, everything was cool or warm to the touch and all components stayed below 90F.

Any help is appreciated. Am I over-propped? Should I reduce the timing? I figured the batteries or motor would be hotter if I was over-propped.

[jkflow]

How 'hot' do they get?
Cable rating is tied to temperature increase. As a rough guide, anything up to 160F on wires is ok but insulation must be rated accordingly, which is typically the case on ESC and batteries. Just don't use this rule in the general world.

Yes, smaller prop results in less current draw.
Yes, reducing timing will also decrease current draw.
Both will result in cooler wires.

[Panchothedog]

6-S on a 4082 with your 1250 kv I would not think you are over proped.
I run that and sometimes even a x-448 with a 1600 kv with a leopard
4082 on 6-S. As far as timing goes I won't comment because I really don't know, I never mess with it and never seem to have a problem. The previous
Post says it will help to reduce it so you should certainly give it a try. If you were spinning too big of a prop all of your other components would be a lot warmer.

[LibertyMKiii]

We can assume the ESC and motor are trying to get much hotter than your wires, however the water cooling is doing it's job correctly.

Are all 3 wires the same temps +/- 5 degrees? A bad solder joint could contribute, but it sounds like more than likely is either the prop is too much for the system or the boat is running very wet. (causing higher amp draw)
Could you adjust the battery position further back? My suspicion is mostly towards the boat running too wet.

This past weekend on my boat I tried a forward battery position and lost 5 mph and picked up around 10-15 F. temps. GPS speeds are a useful tool when getting the boat dialed in.

[Mike W]

I have always found the motor wires hotter than everything else on all my boats.

[Capt. Crunch]

I once had this problem, connectors & wires very hot!

I went from 4mm to 6mm conns & no more problems.