Trying to help someone in another forum

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Hydro Junkie

Well-Known Member
Joined
Oct 2, 2006
Messages
5,714
As I said in the title, this guy needs help and he's not getting it in the other forum. Since some of you know a lot more than I do about ESCs, batteries and motors, I figured I'd throw this one out to you. Here's his first post:

I’m running this on a bench on a rig to test for thrust and power consumption. Sadly I can’t even get that far. Here’s what I got setup:
110KV 4500 watt inrunner dc brushless motor. Liquid cooled by inmmersion in water. The casing is sealed meaning no water can enter the motor internally to damage it.
Powering this thing is a 50v 200amp ESC. Also cooled by immersion in water. Was blowing 120amp ESC’s but I stepped it up to a 200 and haven’t had a problem with ESC’s since.
Battery is 14s lipo.
Prop is a custom design with a diameter of 5.5 inches. I assumed that I was over propped and shrunk to 3 inches to see the effect. Blew another motor.
I have all the data in the world for how this system behaves: RPMs, temps, amp draw etc.
Anything you want to see I have it.
I’m a longtime lurker on this forum and I’m really hoping someone knows how to help me problem solve this because I’m at my wits end!


Just at first glance, I'm thinking too much battery. Any other thoughts?

Thanks Guys
 
First off 14S = 51.8 volts at 3.7 per cell and charged to 4.2v = 58.8v which is not going to work on a 50v esc. 110kv is in the 5000 rpm no load range and not much RPM. Over 3 inches diameter sounds like a trolling motor range? What pitch and what kind of hull are you using and what speeds are you going for?

Mic
 
We need more information to help. The numbers don't add up. If he has the data, show it. If the motor is rated for 4500W, then at 50V he better be under 100A of DC current.

Flooding the stator is common on large motors, but you don't use water typically. If water is getting in the airgap it will add a huge amount of windage losses.

I hope he is not trying to flood the interior ESC compartment with water, but it sounds like he is making his own trolling motor and submerging the ESC in water.
 
He is lucky that he didn't burn up his garage/ house 14s on a 200amp esc what kind of boat does he have a 10ft numbers dont add up !!!
 
Last edited by a moderator:
I've asked for more info, no response yet. Since his questions are based on a test rig set up, I think we're going to have a hard time helping him until we know what he's trying to accomplish
 
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