7XL motor missing/hunting

[DeWalt 1/8th]

Hi Guys

I tried my 7XL motor in my Delta force 29.5 today and had something strange that i have never heard before

when running at full power you can hear a slight variance of revs
all i could describe it like is like missing/hunting you get on glow/petrol motors.

Has anyone struck this before ?

I have checked the controller on castle link all at right settings

I put my 9XL in the boat on same controller could'nt tell if there was any variance of revs (revs are a lot lower )

both times boat was run on dead flat water

[flip3d]

sounds like what my airplane does when its pullin more juce than the batts make.

flip

[DeWalt 1/8th]

I wouldn't have thought so but maybe !

Im running 4s1p 4500mah 22c continuous 40c burst Lipo cells
Castle Hydra 120 speed control

was running X637 and Grim 40x52 3 blade on the 7XL motor and only doing short 100-140 mtr blasts



another boatie in our club is running the same cells/motor and X642 prop in race trim no problems

[andym]

You obviously have the currant limter on. A 7xl in a 29" hull on 4s can realy pull some amps, if you must use a 7xl try 30-50c batteries with the currunt limiter turned off and a m440 or m442. A detounged x440-x442 will do but you will find you will do motors or esc every now and then as the amps will be high. A 9xl with a m445-m447 might be a better idea. Or a nue 1515 1y, hydra 240 and a 47-51mm prop.

[DeWalt 1/8th]

You obviously have the currant limter on. A 7xl in a 29" hull on 4s can realy pull some amps, if you must use a 7xl try 30-50c batteries with the currunt limiter turned off and a m440 or m442. A detounged x440-x442 will do but you will find you will do motors or esc every now and then as the amps will be high. A 9xl with a m445-m447 might be a better idea. Or a nue 1515 1y, hydra 240 and a 47-51mm prop.

Andy yes the current limiter was turned on,Don't think i will disable it either, normally i run my 9XL in that boat, but was having problems with my new hydro that the 7XL was supposed to be in.
Worked out that the Hydro and the Delta both to heavy for that motor.

I put the 7XL lipos and speed controller into my old Oval Master 26 ( 1 pound lighter) today and ran it , no missing or hunting sounds to be heard
I think i might leave it in the Oval Master and work out where to put the GPS, man that thing rocks

[peells]

I have a sintillion 100 amp speed controller using a pistik it is supposed to handle up to 12s lipo 36 cells nimh, for those heavy boats you might give that a try with more cells like 2 4s in series with a lower kv motor like 1500 or so which would be about a 11XL that should geter done! and you wont fry the controller either.

Pete

[DeWalt 1/8th]

Pete in the classes we run we can only run 4s1p at the moment, it would be nice to run 4s2p it would be a lot easier on the gear , that hydro that i was going to put the 7XL in is little on heavy side thats why i needed to try the motor in another boat, but the delta (5.3 pound RTR ) was obviously to heavy for the motor as well.
its revving freely in the little ovalmaster and reaching good speeds