Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[TugCowboy]

Hi Guys,

I've just installed a new Mtronik 15 amp marine ESC into my Harbour Boat. Both motors (Graupner Speed 300's) are running fine however one is slower to respond to any input than the other, there's at least a one second delay before anything happens.

This only happens when they are run off the same ESC (Which is how I want the boat set up) if I stick another ESC in it works fine with no delay. All the cables to the motors are the same length, its being run simply off the single ESC with a Y lead from the ESC to each motors + and - terminals respectively.

Changed all the leads round and there's no difference there. Re-wired the entire thing and still the same.

Is it the motor? (its only 10 months old) both were put in as a pair new. But I can't work out why its only happening when its off the single ESC and not the duals.

Any suggestions anyone?

Alex

[Roadrunner]

If both motors run fine with a different esc and one delays with your new one that would indicated something with the new esc is effecting the motors, it could be the 'delay' from neutral to reverse, i know the mtronic esc's have a 0.5 second delay time there, you will want to check your settings to full forward and reverse with no delay to eliminate that problem.

Have you suppressed the motors at all? this could be worth doing. apart from that try another motor where the one that is delaying, and see if the problem vanishes. if it does that indicated that the motor is going bad, if the problem persists then im out of idea's apart from using a larger esc (20A).

What size is your tug? 300 motors are quite small for a tug i would consider upgrading to 400's if you have the space, or if the motors are about to die!

Inherent problems with using 1 esc for 2 motors i think this is a common problem not just limited to you, i have always used 2 esc's and a mixer for twin motor setups, so never come across this issue to deal with ...

is the delay that long that it effect the models performance in anyway? i doubt it will make any real diffrence with a delay, worse case is the model steers a bit one way when throttle or reverse is added...

[grasshopper]

can only imagine that the slow motor is ever so slightly less efficient than the other one and needs a tad more 'oomph' to get started than the other...

The manufacturer of those motors (probably Mabuchi) churn out millions of units per annum*....they won't all be identical.


*just had a look at their 2008 annual report - their maximum capacity for electric motor  production is 2 billion units per annum!!

[TugCowboy]

Thanks roadrunner.

They aren't suppressed at all, perhaps thats something I could try. I've got another motor I can put in there but its quite a bit larger (600 I think) would that be ok to test with? as its a big torquey tug motor.

I'll try a larger esc but the previous one in there was only a 10 and I've upgraded it to the 15, it always ran fine with the 10a, although it was a rather old bulletproof one.

Its not actually in a tug, its a Billings Samson kit, a dutch Harbour/River Pilot boat. Certainly not a fast one and never used for towing, just nice gentle sails on a Sunday.

Grasshopper,

Might be time to change motors then. Are there any manufacturers that do pre-sale pairings? I don't mind paying for a decent pair! (that sounded rude)

Alex

[Roadrunner]

To be honest i would chuck the 300 motors as previously stated there knocked out rather a lot so no real quality there, swap them to Grapuhner 400 size motors (£6:50p each) and run them with the 15A esc, and suppress the new ones, 3 suppressors should be fine i would have thought.

No guarantee that the new motors will work any better in delayed starting but the odds are in your favor as a 'quality motor' not only that you will get more torque out of the boat which is what a tug needs really.

[grasshopper]

Have you considered wiring them in series rather than parallel?  As you're driving them from the same contoller that might make them start together.

[Roadrunner]

The problem with that is one motor will have far less power going through it as the majority of it was used by the first.

Remember how lights work in series, first bright the next dimmer and so forth.. same principle with motors, but worse as motors do draw a lot more current.

[TugCowboy]

Well I have just ordered a couple of brushless motors and some ESC's for another project. I might give them a go in this first. Thanks for all the advice guys. Somethings dud somewhere and I guess we will just have to go through them one by one and see what it is.

If it works with the new setup I might keep it that way.

Alex

[malcolmfrary]

Being run off the one ESC, both motors are being offered the exact same power, so all other things being equal, they will both start together.  It follows that since they don't, something is not equal.  Is it a delay, or does one motor just need the stick advancing further to start?  If so, its either the motor getting tired, or the shaft that it is connected to is not quite as free-running as its mate.