Hi Highwayman, that's right shipmate, you come over and join us sailing people, we don't get those nasty motory things worrying us. In any case, they say that they won't last, they're against nature, for one thing they'll run out of all that juicy stuff that they run on and where will they be then.

Nerys

Hi highwayman,

RE:- Might just go over to yachts.

Now that is a hole different game altogether. so I have been told.

Martin555.

After talking with Mtronics it would seem that 4amps is not an unusual draw for 400 motors. 2 400's in the Pilot boat was considered to be pushing it a bit. When compared to the Race400's recommended by Aeronaut then the Mtronics 400were of much higher revs. I have 2 unspecified 380's at much lower revs, slower but no issues. Might just go over to yachts.😁

Awaiting for a call back from mtronik. latest test proves faulty motors. MT specification states 12v nominal 1 Amp current. After buying a new multimeter, mine was 30 plus years old I ran a motor from 12v 7amp hr battery. After 2 minutes the motor was drawing 2.87amps and the casing temperature was 47 degrees C. I await the call.

Sorry to have to say it but It sounds like redpmg is right these motors are faulty and need to be replaced by the supplier.

Martin555.

Yes

So are you saying that the motors are not connected to the prop shafts. ?

Looks like my post crossed yours Red.

Martin555.

Hi HW ,
Take it you mean they are simply clamped down with nothing attached.
If that's the case it would seem you definitely have a pair of duff motors .
Think you need to be having a few serious words with mtronics
You might also think about getting a pair of 385 motors instead - much more torque with 5 poles - and unless its a speed boat work much better - but beware like the 400s there are some serious amp eating versions around - ask your supplier for advice and get a pair that will happily run on 7.2v.- ones rescued from better halves old hair dryers prefer 19 to 24v.........

I have a bench no load fixture I made. they get extremely hot under no load after 5 minutes at max stick movement. They should be operating well within tolerance.

Hi HWman- Martin has led to another chain of thought - are the motors connected up to your propshafts ? - if so another silly question - are they filled with grease or an oil mix?

Very first RC boat motor ran very hot - struggled for power - had taken advice from a magazine and filled the tube with Lithium wheel bearing grease. Joined a club and the first bit of advice was clean it out - use an oil mix with a spot of grease to thicken very slightly . Problem solved , boat planed easily - motor ran cool ...........
Now use a touch of Silicone grease with two stroke oil ( left over from Seagull days)

Hi highwayman,

RE :- No these motors are brand new. bought to replace the 2 that warped the engine mount on my \aeronaut pilot.

As these motors are replacements i was wondering why the original's warped the mounts. ?
So this might sound like a silly question but have you checked the motor/shaft alignment ?

Martin555.

Has anyone got one of these motors and can measure the resistance across the terminals, and then compare to the resistance of these ones. may have to move the shaft to try to read all 3 coils.
Regards Roy

"have had a couple that started to make a lot of very nasty noises and produced an alarming amount of smoke and the beautiful aroma of cooking motor "
'Methinks the carbon brush doth protest too much!' 😁 (Sorry Willy😔)
Rules are made to be broken Red👍
I never had any that did that. Bad luck😮
A few grumbled and groaned but a little 'running in' forwards and backwards fixed that.
Even my modified Taycol Target now runs backwards just as sweetly as forwards😊
As did the Supermarine that I modified for Colin.
Cheers, Doug😎
PS. I don't regard a healthy discussion and exchange of experiences as arguing Red👍

Hi Doug - hate to argue but have had a couple that started to make a lot of very nasty noises and produced an alarming amount of smoke and the beautiful aroma of cooking motor - however agree with you that these are more likely to be Friday motors that someone wound the wrong way.................

Hi Red,
"One silly question - are the motors marked for positive & negative - often just a red dot for positive next to the connection. Come across some motors in the past that really did not like polarity reversed. "
Unlikely I think. The brushes might protest, cos they're shaped / worn to run in the 'forward' direction. At most I guess it might increase the current density in the brush gear, due to a smaller contact area when running 'backwards', but not to such an extent as to cause excessive heating noticeable in the can.
I reckon highwayman (🙄) has got a pair of motors from a duff batch☹️
Cock up in the windings is my bet.
Cheers, Doug 😎

Sounds like you have a problematic set of motors - perhaps you should try a query to mtronics - if you advise them you are also seeking help on the MB Forum you might get a response quicker !!

Sorry the increased voltage did not work - perhaps oiling the bearings and running in on a lower voltage as Doug suggests might help.

You could test them on lower voltages and see if they still get really hot - if they do so at 4 1/2 volts for instance there must be something fundamentally wrong with them. Are they getting hot enough to distort plastic or similar to a baked potato just out of the oven ? Any smell of burning ?

One silly question - are the motors marked for positive & negative - often just a red dot for positive next to the connection. Come across some motors in the past that really did not like polarity reversed.

A forlorn hope perhaps highwayman, but have you tried a few drops of machine oil on the bearings?
I also wonder if there might be a short in one of the rotor windings?
Cheers, Doug 😎
BTW; I usually 'run in' my new motors by running them an hour or two at less than half the nominal voltage😉

No these motors are brand new. bought to replace the 2 that warped the engine mount on my \aeronaut pilot. I tried running them on 12v. result was hotter faster.

Strange these motors should run so hot, are they old, do the brushes
and commutator need cleaning.

Data sheet for 400(20w)
https://www.mtroniks.net/download.asp?ResourceID=2126

Thanks redpmg. I have a 12v battery I was planning on putting into a scratch built anchor handling vessel I am building. I think I will divert it for some bench testing. I'll let you know the outcome.

Not found - only a pair of vision marine "400" (5 pole like 385's) - rated 4.8 to 12v - Hi Torque. Similar size to my mtronics ones - but obviously different. For the life of me cant remember what the boat ran on - have some 6v and 7.2 packs so not sure which.

However found this data sheet for the 400s on the mtronics site
Should be fine up to 12v - but there's a clue in the 12v stall current - 27 amps - these specs are for a normal length case and they say "new range"so yours are probably different
None of my "hot" 400's have a stall current that high
One planed my 19 1/2"police boat avatar drawing less than 10amps - but it did blow a 10amp fuse when the prop locked with weed - stall current turned out to be 14amps .
Try using a higher voltage - be interesting to see what happens- supposedly draw less amps with a higher voltage - might help with the heating

Also have a pair - shorter than normal 400. Went on about watercooling and lower pitch prop

So Whoops - pardon me - now seen you said no load - only thing could be they are not meant for 7.2v - have you tried them on 6v - not sure what Im using - not run that boat for over a year . Might have yet another pair loose - if so will try those and see what they do on 7.2v

Lot of the Graupner full size 400s are meant for 6v - but seem to take 7.2v ok - they did have a 7.2v rated one too - much more powerful than the 6v ones - George Turner used to run those on 8.4v in his fast models