Sanity Check - kv Vs Amps Vs mah for small bolt

[rake]

Hi forum,

I just got my hull back on the water and am running the following setup

2200 2S Mah 40-50C Turnigy
4800 kv inrunner
45 amp ETTI NAvy 45 ESC

Am I pusing my luck with this ?

She should give 35500 rpm
Max potential draw of 88 amps (40 x 2200)

Many thanks.

Rake

[NativePaul]

It is a reasonable setup for a small boat, but you don't mention prop size, too big a prop can make any setup unreasonable.

I ran a mega 16/15/2 a 400 size motor of the same KV on 2s 2200mAh with a Castle creations Phoenix 35 ESC for years in 450mm/17" cats and riggers in our Mini Hydro class, an X428 was what I needed to get the 5 minutes plus mill and in lap the class needed, but the gear was happy enough pulling an X632 for about a minute of sprinting too.

[Fluid]

Actual loaded rpm will be closer to 30,000. The "max potential draw" does NOT mean the motor won't pull more, depending on motor size, boat size and prop the amp draw could be well over 50 amps. We need more info...exactly what motor and what is a "small bolt"?


.

[revoltrunner]

"what is a "small bolt"?
http://hobbyking.com/hobbyking/store...arehouse_.html

[Alexgar]

If its the 20-40 4800kv inrunner for hobbyking it says 25 amps so a 45 amp esc should be sufficient. I run a bigger motor in a similar sized rigger and the 30 amp esc hasn't gone yet

[rake]

Thanks all.

The setup is as described a 20-40 4800 KEDA motor.
15 inch hydrofoil on the stock prop and tube.

This little boat has history, it has been smashed bashed and sunk to a few lakes and I have lovingly re glassed and rebuilt her a few times.

The old issues were loss of control and Tx / Rx loss. The failsafe is now working so hopefully wont happen again.

On its first test drive since rebuild the other day I had parts of the run where the boat did not respond to the Tx and stood still in the water.
It was not low voltage I dont think as after a few mins rest she got up and danced again. The motor and cell were not hot to the touch either
so this left me a little stumped and I thought my set up might be drawing to much and sending the ESC into cutoff although I cant be certain.

the motor is not the hobby king one, it is this

KB20-40-12L

108196.jpg

http://www.giantshark.co.uk/product/168486/keda-kb20-40-12l-4800kv-inrunner-brushless-motor

[NativePaul]

I'm not a fan of 20mm motors myself, I have seen a fair few being used and run a couple myself, all ran hotter than I thought reasonable for the power output and especially so the cheap ones, a 28mm 400 size motor will only be 10-20g / 1/3-2/3 OZ heavier but has much better cooling potential.

Oh and 3s 1500-1600mAh will weigh about the same as 2s 2200mAh, and matched to a 3000kv motor will spin the same prop faster for the same runtime due to the higher efficiency of the lower current draw.

[rake]

Cheers Paul - appreciate the reply but I dont thing the little bolt motor mount will take one nor will it have the space in the hull / roof cavity dimensions ??

I like the 3s idea.

I did once put a pair of 2S 2296 nano tech in with a coupler and it flew on a 2600 kv