Plett/Ultra Heat problems! Please Help

[Tony T]

Ok, since no one made any comments reguarding the heat I was getting with my big 40 inch boat in the video posting thread... I'll start this thread. This is the boat with the twins. The motor that is running opposite for the right hand prop get really hot around the brushes 200 F. The Left hand motor got up to 180. The heat discolored the comms to a much darker copper.. Both Can temperatures where about 100 F with full cooling. There was a small about of comm fire visible.. but very little. Since both the motors are 6 turn 10 V with the torque rings. Should I increse the timing a hair.. right now they are set at the Factory settings at the first mark. Oh, the props being used are X442 L & R hand. running on 2400's 12cells each.
If you need more information to help me with my quest to solve the heat let me know.. I don't want to run this boat again with out some good information on what I can do to solve the problem.
Thanks.

Tony
http://www.kelownafastelectrics.com/pictures/mercury-16a.jpg

[GundamExpo]

Mark the factory timing on the can, lower the timing a degree and see if that helps, I dont think rasing it will help, but it might. Dont run it for the full time whenever you make timing adjustments, just a for 30-50 seconds. You may also want to decrease the prop size, or do some prop work, such as cutting off the toungues on the props. Your comms might also be glazed so cleam them with a comm stick.

Just keep in mind that if you adjust the timing on one motor one way, you have to do the opposite on the counter rotating motor. Im guessing that the plett stock setting isnt neutral, so you have to find the opposite setting on your counter rotating motor.

Example.

Regular Motor : +2 timing
Regular Motor Rotating Backwards : -2 timing

[Tony T]

Thanks.. This is the nice thing with these Graupner Ultra's they have marks on the can for timing, plus they have it on the opposite side for running reverse. and a mark where to change the position of the torque ring to match the different direction.
I'll play with the timing a bit (man I hate doing that). I'm gonna try and avoid messing with the props.. to bad Octura doesn't make a X440 L & R hand :p The Stock timing on these motors is the first mark advanced.. assuming it's degrees.. but I don't know. Thanks Keep the thoughts coming.

[GundamExpo]

Prop mods may be the only thing thats going to get your temps down. I had to cut off the tounges then do a mild texas cut on a X642 to get it to work on my SC26. IT was the texas cut that dropped armature temps 20 degrees. The motor was doing abot 180F before the prop mods

[Tony T]

Umm... interesting.. I'll try the prop mods first then.. since the timing does look ok given the condition of the comm. For others here is what a Texas Cut is..

"How to Texas Cut" This is a term that is often used, and commonly misunderstood.
A simple Texas-Cut, is sharpening the leading edge/ > More specific/ > Remove blade material along the leading edge/ > Contour or cut-back the leading edge, from the blade tip > hub. Instead of a gradual blend in the leading edge, cut it at a straight angle from the hub. This reduces the overall size and Dia. of the prop. without removing pitch! This generally improves prop efficiency, and helps to un-load the motor; while not greatly changing the Aspect-Ratio > Pitch divided by Dia.
Wrote by : Paul Govostes

[Tony T]

Giving this some thought.. a texas cut might not be the right thing for me to do on this boat, because the hull likes larger dia. props.. and a texas cut will reduce the dia. some what.. What I think I'll do is remove some of the tongue, and back cut it some too.

[Steve Vasdekis]

Hi Tony. Graupner makes 40mm props right and left. Offshoreelectrics.com has them in stock.

[Andrewg]

Tony

have you checked the motors are

* drawing the same amount of current
* turning the same rpm
* have you tried changing th battery packs feeding each motor
* is each drive unit having the same effect on the motors current draw when hooked up, free running?


it may be there are variations in each motor - timing marks are not the most reliable indicatoprs despite what manufacturers claim; the packs could differ in performance under load - thereby loading one motor; the drive units could have different amounts of drag, your props could have slight differences.

also the speed seems modest - are the motors running in an efficient voltage range?

[Tony T]

Steve : Umm. I'll have to look into that one.. Thanks.

Andrew: I have no way of testing the RPM, I can only check current under no load. As for the Batteries. I've seen the same results on two seperate runs.. both pointing to the reverse running motor. I'm thinking the reverese running drive does have a higher amount of drag.. there is some play in the prop shaft forward and back.. I've compensated for the thrust .. but it may be pushing to hard on the gear.. cause it to bind a little. I've had no luc kthus far in getting a replacement propshaft/gear. As for the efficient operating range.. doubtful.. they are 10v motors running on 12. one thing I've listened to is the rmp difference.. when they are running under no load.. just from the sound it seems like they are very close.. but I know thats not the best way of doing it. What I was going to do is make a wire harness to have both motors sharing all the packs .. thus draining them down at the same rate.. right now each side is seperate..

[Steve Vasdekis]

Hey Tony, just from watching that small video, did you only make right turns? If that is so, that is where your heat is coming from. When you make the right turn you load the right motor drawing more amps and unloading the left drawing less amps. Try running the boat the same setup, but this time only make left turns and see what the motors tell you.

[Tony T]

I did on the second run, iI made many left and right turns.. and thats where I hit the 200 F.. and the comms changed color. but ya.. I suspected thats where the heat was being caused.. I'm probably gonna get a mixer.. so when I make a corner.. the inside motor is actually slowed down.. I think that might help.

[Steve Vasdekis]

Try dropping a cell from each pack and see if that will take of your heat.

[Tony T]

I wish I could do that.. thats more of a pain.. it would be easier to drop to those carbon 40 L & R props.. I'm beginning to wonder if I should have used 7 turn motors instead.. at least they are 12 V.

[Steven Vaccaro]

Which way are the counter rotating props spinning, to the inside or outside?

[Steve Vasdekis]

Steven, Tony's props are spinning to the outside from looking at his pictures.

[Steve Vasdekis]

Tony I was thinking about your boat today and I came to the same conclusion each time....for that boat to run fast and cool you need to go to 10 turn arms and run 18 cells, you need the extra torque to turn a pair of larger props and reduce your amp draw. This is the cheapest fix. Another idea would be to sell off those 930/6 motors and get a pair of 1800 series pletts and run them with 18-24 cells and go kick some serious booty!

[Steven Vaccaro]

Wont making them spin to the inside give more lift and a tighter thrust cone?

[Tony T]

SteveV, if I put motors like that on these drives.. I'll granade the drives.. the prop shaft can't take it.. poor design.. no cone shaped bearings. if I can't make this setup work.. I have three choices.. 1. get the 40mm carbon props.. and hope it works.. 2. buy one 7 turn arm, since I have another motor with a 7 turn in it. and hope that works well withthe props. (it should). 3. scap the whole thing.. I have about 1700 Canadian invested in this thing right now.. :( I don't know Pagemaster. they way they are now is the way real boats are.. and it seems to make some sense since the props bite into cleaner water this way.. the other way they would bite messed up water from the inside. Thats my therory anyway.

[Andrewg]

Tony

The drive end play has to be number one - you can make any changes to the motor and you may simply be compensating for a mechanical problem in it

It may be a matter of shimmimg up the shafts to reduce endplay and the unwanted thrust loading, seating the bearings correctly or replacing one or two. I am sure the work will be worth the result

On the motors I would try equalising current load when free running and test

Then equalise the motor rpm and test. Heres how to do it without a tacho

Run them together from one pack at say 8 cells so they dont pop their comms - or from a power supply

The difference in rpm will be audible as a beat in the sound of the motors. The higher the frequency of the beat the greater the difference

You can adjust the motor timing till the beat is eliminated and you get a smooth drone (like the sound of this advice lol).

I would keep the big changes in mind. But for now I would simplify what might be happenening and get the basics sorted and work out which way of turning the motors gives the best results then start introducing new variables like props etc if you feel it necessary.

[Tony T]

Andrew.. basically thats one change I'm going to make.. right now it's two seperate systems.. I'm going to make a harness that will have both systems sharing the batteries. I'll be testing the amp draws tonight.. and some other tests.. I'm also looking at a way I can add thrust washers or bearings between the drive dog and the aluminum housing to put the thrust on the housing instead of the gear.

[photohoward1]

290/30 6 turn Pletts are good sprint motors on 12 cells.
I used to run a 290/30 8 turn on 12 cells and a single x437/3
in my Key west. (3 minute enduros) AlanN went to the 290/30 7 turn and it was to hot.
Our boats were much lighter and had surface drives. With the weight and the 2 outdrives cutting the water I think an 8 or even a 9 turn might be needed.

You could always drop in 2 Hacker 9 or 10xls and those 442 props.
The boat would scream!!!! or even a 14L


HT

[Andrewg]

Tony

I think running the packs of 12 in parallel will equalise what each motor sees and eliminate any variation due to pack differences

With the leg I meant tear it down and reshim the shaft inside so you dont have to add thrust bearings etc which will be more prone to damage. ie get each leg on equal terms but withthe fundementals right rather than jury rigged

The idea of running the motors offf one pack in testing was only so you wouldnt introduce rpm variations due to packs rather than motors per you idea with paralleling the main packs

are we thinking alike?

[Tony T]

Andrew.. you can't shim the prop shafts on these.. there is movement with in the bearing. and you can't take it apart.. You'd really need to see it. Here is a picture I have on the PC..

[Andrewg]

ah

so on these the shaft loads up the gears ? Could it be doing thos in both legs

I take is the big silver thing is a housing of some sort which is somehow bolted into the leg?

I am a little surprised they dont run thrust bearing as stock given the design

those gears binding up will kill power an speed - just as it does on the hughey if it is meshed too tightly

[Tony T]

The right hand drive gear is tight still zero play. The Left hand drive (which got the hottest) has play.. When I put them back together I left some space on that one to account for that play.
The housing you are refering to has the bearing in it.. the housing is held in the drive by a set screw on the top. ya I'm surprised there is no cone bearing for taking up the thrust. Yes if the gears bind.. we are talking some big loading problems..

[Tony T]

I just tested the no load amp draw on the two motors.. initially the reversing running motor was almost half an amp different
right now I manage to get the two very close to the same rate.. But one thing I wonder is how much different the two conntrollers are. I'm charging up another pack to run them at the same time. compair the sound, and the amp draw..

[Steven Vaccaro]

Tony what is the no load amp draw coming out to be?

[Andrewg]

Tony then try them in the drives to see if there is a diff

I think you will find the draw is not as important as synchonising the motors - the draw will vary over the power curve anyway

its indicative - but I remember ed was always red hot on getting the motors turning the smae speed rather than identical amp draw

also it may be time to establish just where real neutral timing is on your motors again as a reference

[Tony T]

Steven, the right hand motor was 7amps on 6cells at first.. and the left hand motor was about 6.5amps.. but as both the end bells warmed up a bit they dropped.. I have them both right now at a very close 6.1 amps. they do sound the same.. One thing I did notice is the left hand ESC will start the motor and hit full power sooner than the rught hand ESC. but once both are on the green they sound the same. I agree there having the motors RPM the same would be nice.. but I have no way of testing that.. the only thing I can think of (bit silly) is attach them to a Speedo and match the postion of the needle on the guage.. How can I establish the exact neutral.. also the torque rings may not be in the exact same position relitive to the magnets either.. I just followed the instructions the motors came with to reverse the one.

[Andrewg]

Tony

re motor synchonisation please see my post above this can be done accurately using no instruments

all tests on the motors should be done first without the controllers so you know what the motors alone do

the add the controllers - and other items. As you introduce them you can see how each one affects your baseline measurement

but they must be baseline measurements

[Tony T]

ah, ok.. well I'll give that a shot after work today..

[Tony T]

Well, I'm in the process of putting the two motors in sync.. Using a microphone, and a Oscilloscope to display the auto signal.. Bit hard because I can only run the motors for short periods of time because they are advanced..

[Tony T]

Here is a picture of the setup, and a pic of the audio image of both motors.. I think it's in sync.

[Tony T]

I now just tested the setup with the ESC's in place.. still holding in sync. Next I'll try it in the boat. In the whole process I had advanced them half a mark. both actually are very extreamly close showing the same timing mark on both motors.
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Ok, for those interested.. here is a video clip of the scope running.. I manage to keep it stable enough to see it.
http://www.kelownafastelectrics.com/motors.mpg
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Ok, I've now tested it with the motors in the boat.. even though with the added 'noise' from the gears in the drives.. they still apear to be in sync. "Hopefully" the loading from the drives will not be a huge problem.
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Earlier I also had a good look at the position of the torque ring on the can based on where the magnets are, and compairing them both.. they appear to be in the correct location, so the current timing position of each appears to be correct and the audio signal shown on the Oscilloscope looks and sounds stable.

[Tony T]

Here is another picture showing the scope with one motor, and Both motors.

[Andrewg]

Tony thats a helluva way to do it

I assume it was a mess which gradually worked its way into a single sine wave which then stabilised as single sine wave pattern (in synch) or did it blur then reform (out of synch - by about 30 rpm by the look of the video)

Now you will know now if the problem remains it is in the drivelibe or simply a characterictics of the motors loading up one one side

BTW I saw on ezone they use mixers for multi motored planes so it should be easy to do if needed

[Tony T]

in the video they start out of sync.. because one motor starts before the other one does.. but once they hit full power the two combine.. as seen in the last picture.. that was as best as I could get it.. you can see the sine wave behind the dominant sound also. Even lightly pushing on the endbell causes them to fall out of sync.

We don't have a manual for this scope.. so if there was a way to hook them up with out a mic. that would probably yield better results..

[Andrewg]

Tony

got it now

I think that is about as precise as any way you can get - and way better than all but a very few are using.

once the sine wave stabilises they are in sync and maybe you will get a fraction of an rpm better (keeping in mind if you watched it for 10 minutes before it moved out of sync it might be 3 rpm/hour out!!)

I suspect variations elsewhere such as driveline friction and prop shape may have more effect

just out of interest do you have two motors you can put out of sync and then retune by ear by eliminating the beat and compare how it fares vis the oscilliscope

Please let us know how you go this is a great wya to set up a boat!

[Steven Vaccaro]

Tony the Carbon props are on the way! Sent them out yesterday morning. Please tell me more about the scope idea, I have a scope and would like to adjust my 800bb's this way.

[Tony T]

Andrew, ya it was a lot more 'fun' using that scope V.S. doing it just by ear. I think I played with the scope more than acutally using it for the motors.. :p Well off hand no.. I don't have any other motors that are the same in which to try a 'just by ear' setting. My Dad want to see if there is a way to set a motors 'timing' using the scope. ummmmmm..
--------------
Thanks Steven, well on the scope we have here I just pluged in a microphone to the vertical input & ground.. and set the knobs to a proper seting.. here is a picture of the setting I had used.. perhaps you have simlar settings. Once I receive the props I'll test the boat again.. Hopefully next weekend.but being that you send the props later I may not have it in time for next weekend.

[Andrewg]

My Dad want to see if there is a way to set a motors 'timing' using the scope. ummmmmm..


Tony you can read the rpm off the scope no?

ah I thought the way was to check the current draw with a plett very delicate it seems when one plays with advance.

[Tony T]

probably not with this scope.. perhaps a newer one..

[Steven Vaccaro]

Sorry about sending them a day later! What happened was I was thrown a curve ball when I made out the online documentation and decided I better make a special trip to the UPS office to make sure I send it the right way to Canada. And Im glad I did I also had to fill out other paper work to send along with the UPS label.

[Tony T]

oh well.. I was a bit surprised you sent them before receiving the payment. But that went in the mail back on monday anyways.

[Steven Vaccaro]

I wasnt worried about the money. I am interested on how they work, and want to see your project work for you.

I was worried about sending it out correctly.

[AndyKunz]

Tony,

I just found this thread. If you have a dual-trace scope, you can set them for the differential and hook up mikes on each input.

Andy

[Tony T]

We had tried hooking up the mic on the horizontal input, but nothing happend.. I could try two signals and see if that does anything..

[Tony T]

Well I don't know if the 2nd input works or not.. I couldn't get anything.. but I did figure out how to make the display stable. so I re set the timing on these motors again.. and it was a single signal with both motors runnning.. but why they are running the two vary in harmonics every couple seconds.. then realine to one again. I'm gonna test them again hooked up in the boat and see how that goes.. Here is another video clip of the two motors running. I have the read out stabilized. and on 6 cells the two become one once at full power.
http://www.kelownafastelectrics.com/motors-sync.mpg

[Andrewg]

Tony

what happens to the current draw if you put them in the outdrives?

I am keeping in mind no difference until they are under load and they geartrain is perhaps binding a little

[Tony T]

umm, you know thats one thing I have not tried yet.. good point Andrew. free running I know there is no binding. But how much of a load are these drives dry.. probably not much in comparison to the torque rating of these motors..

[Andrewg]

the things is tho when you do make observations withthat setup you will know the motors are very much less likely to be the cause of problems

the confusing thing may be the pack variations

Just do two runs and swap the pack/motor combo after a recharge to establish whether they are a problem

then all you have left to do is swap the motors across the outdrives over two different runs

Gee you have a lot of reasons to spend time at the pond!!!

[Tony T]

swaping the motors can't just be done at the pond.. It requires a fair bit of work.. reversing the motors, re sync.ing them to match.
After reviewing the video footage from the original first two runs .. I did notice the RPM difference in the two.. I'm sure when I receive the carbon props from Steven, and the two motors are in sync. it may just solve the problem.. though I have advanced the timing a bit.. I wonder if I should test it with the X442's again. as if I run the 40mm carbons which may not require the more advanced timing..

[Andrewg]

Tony

One change at a time so you know which variable is the one that is important


It may be the motor change - ie the driveline is the most important factor in the heating

the packs first then the drives

If its the differential you want to eliminate lower pitch props wont have any effect

And once you have indentified the probelm you may find you are travelling faster and looking at pulling a larger prop rather than a smaller one

I will have a muck around with mymotor calculator and let you know what it suggests. I can pic a 700bb in a mono or a 24 cell SAW rigger to within a mph or two.