2 quick questions...ESC & cooling line.

[Emeraldtarpon]

Hi all,
1/. I'll be running a 2860, 2190kv motor that has an amp rating of 45A.
I'm looking to purchase a 70A ESC, so I have that approx 30% more than needed, for safety etc.
Will this ESC suffice? OR should I up it to 90A?

2/. I'm wondering about cooling line dia'. Due to the dia' of the inlet/outlet nozzles on the motor/ESC, it looks like I'll be using 3mm x 5mm line.
Will this be a sufficient enough dia' to keep my running gear cooled efficiently?
Thanks for your help, cheers all.

 

[Dave Gilles]

in the upper level of electric RC boating its common to pull upwards of 350A. No one looks at the amp ratings of a motor we look at the wattage rating because that factors in the voltage and amps. A common 2860 will handle 1200w-1400w. That size motor is typically 2s or 3s in which your KV is totally wrong for. you have a 4s KV picked out. on 2s you will pull 200A to get close to that motors wattage rating. on 3s you would pull 133A.

your KV should add up to around 30k RPM tops. the reason for this is it matches the prop size to the hull. if you are too high you have to run too small of a prop to not overheat things. if you run too low of a KV you have to run way too large of a prop to go fast. so you have a 4s KV picked out but you have a motor sized for 2s wattage.

150A esc is pretty common and doesnt cost a lot more than the 90A. But you could get away with a 90A if size is that much of a concern.

 

[Emeraldtarpon]

Thank you very much for your explanation Dave.
I'm still trying to wrap my head around this stuff so unfortunately, I don't fully understand your explaination.
I've basically copied an upgrade for the same boat, off the internet.
In the upgrade, a 2860, 2040kv motor is used but I couldn't get that motor so opted for the closet kV I could find...2190kv (same brand motor, slightly higher kv).
I've obviously gotten in over my head and am doing stuff I don't understand which I know will lead to failures if I go any further.
I've been thinking I'm going down the right track by copying an upgrade but it sounds like that is a mistake...so now, I'm basically more confused than ever.
What would you suggest Dave...how do I rectify this as I have the 2190 motor coming in the mail.
Use 3s and 150a esc??...very sorry for my lack of knowledge.
I'll check my prop size too and get back to you asap.
Your help is very much appreciated Dave, thank you.
(I'll understand this stuff, eventually).

 

[Emeraldtarpon]

30mm dia prop

 

[Emeraldtarpon]

After looking into this more and checking out some examples, I'm going to try the following.
Up the ESC to atleast a 150A
Use a 3s battery
Change prop size to a 36mm dia'.
I expect a drop in overall top speed using the 3s (may be able to rectify that somewhat with prop size?) but I think the boat will still be way fast enough for me.
I may try a 40mm dia prop and see what the result is.

Could someone PLEASE let me know if I'm atleast in the ball park with this...it would be very much appreciated, cheers.

 

[Dave Gilles]

if you're going to keep that 2190kv motor you can get an octura x637 prop for 3s. you can get cheap brass props off offshore electric or zippkits to try out also. 40mm and 43mm. octura x640 might be another prop to get.

40mph with a 150A flycolor would be a good starting point. which the props I suggested will get you.

 

[Emeraldtarpon]

Thanks Dave, I appreciate your answer.
I've actually been looking at the flycolor 150 + program card so I'll get that in the mail.
Will take your advice on props...I actually purchased the 2860 from OSE (I'm in Australia) so looks like they'll be getting another order from me.
It takes a while to get here in the post but the prices in Australia make the wait worth it (rc gear is ridiculously priced here...terribly OVERpriced).
Appreciate it mate, cheers