Help with 120amp Hydra

[electric]

Help. I have a Oval Master 27 with a 120amp 50volt hydra (brand new) esc running a 9xl nemisis(sp) motor. I tried it with 12 cell Intellect batteries and then with some 7.2 volt Lipolys with the same results. The boat takes a moment to get going and than planes out and runs a short distance and stops. When you give it throttle it pulses the motor and I am able to bring it in. I tried the two different sets of batteries described above. I measured the motor temp and it was very hot 150 degrees for such a short distance. The esc was fine. Any suggestions I could try tonight before I make another attempt tomorrow? I do have some 11.1volt lipolys I could put in to see if it is a voltage issue? Open to ideas. I also have the ability to program the esc with the castle software. I should also mention that I believe the prop is either a 642 or an m440 (it's been awhile not sure what it is). I ran the boat a few weeks ago with SV27 gear and it ran great.

[Mich. Maniac]

I feel ya with the frustration and clueless guessing as to what It may be. Sounds like your gonna have to do some simple eliminating. first change motors if you have one. put sv motor back in with small prop. If you dont have motor... change esc's and try your nemesis with that esc. Check your connections to make sure solder joint or something isnt blowing off with high voltage but still feels and looks connected. There is a thread somewhere that tells how to check voltage per motor lead with motor disconnected. I think that will tell you at least if you have a bad set of FET's. Doesnt sound like you do. maybe a engine bolt too long and rubbing inside or something. good luck.!

[JimClark]

Check the programming especially the cutoff voltage and the throttle curves

[electric]

Thanks, I am going to try a smaller prop today and I did get my "watts up" meter set up last night so I should have some data on amps, volts etc.. I am also going to go with my high end lipoly's and see what happens. I will let you know.

[Fluid]

You can try a smaller prop, but the motor temperature is troubling - it 'could' have an internal problem. What were the temperatures of the ESC and the cells? Did you change the low voltage cutoff setting? If you have low-performance NiMH cells they could be the problem. The 2S LiPos did not work because the lowest voltage cutoff on the HV controllers is 9 volts.



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[ReddyWatts]

Does the prop shaft turn freely, cleaned and lubricated? Could your motor mounting screws be too long and hit one the windings? Did you leave any play between the strut and the prop?

[electric]

Hmmm. The esc was cool and so were the batteries. I did put a smaller prop on(an old sv27 plastic prop) and I am going to put in some 11.1 volt lipoly's and see what happens. I will provide an update once the the early morning fisherman are done and I can run it. I should have some stats on voltage amps etc..

Hey, with 2 X 2s Lipo's that should give me over 14.4 volts will that not be enough with the 9 volt cutoff?

[electric]

Mounting screws are not too deep. Prop turns freely. Some play on the strut, although I will recheck that.

[Raydee]

Was the motor new? I had a new one right out of the box do just about the same thing, except mine ended up burning up my ESC. I would swap the motor out and see if that fixes it.

[Fluid]

Hey, with 2 X 2s Lipo's that should give me over 14.4 volts will that not be enough with the 9 volt cutoff?

You said you were using "some 7.2 volt LiPos" not 4S2P (2 LiPos are 7.4 volts BTW, four are 14.8 volts nominal). 4S should be plenty for a 9 volt cutoff.

"Cool" tells me nothing - what was the temp of the cells and ESC? Where did you measure the temp on the motor?


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[D. Newland]

Are you running a separate Rx battery pack and did you pull the center red wire on the ESC to disable the BEC?

[electric]

New Data. Watt's up gave me the following: 19.73 Volt Max, 109.75 Amp Peak!!, 2137.9 WP! These are troubling numbers. The boat ran about 75 feet and stopped. I was expecting the amperage to be around 70 or 80 right?? I was using a SV27 standard 3 blade prop which is pretty low key. I should not be getting that type of amperage on something like this right? I was looking at the gap between the prop and the shaft and it is pretty tight. I have maybe a 1/16th of an inch when normally I run about 1/8". Could that be binding the motor and causing the amp draw? Possibly I should move up to a 10xl motor?? I did not get any temps this time because I had to wade out to get the boat and walk it back to the house, by then the numbers are pretty useless.

[electric]

To answer some other questions:
1. There is no BEC on the new High Voltage Hydra 120amp esc.
2. I measured the motor temp on the back of the motor, furthest from the drive shaft. Rememer it was 150 degrees on about a 75 foot run.
3. I did not measure the temp on the esc, because I am telling you it was cool, the motor was hot so I just measured that.

[Mich. Maniac]

Mounting screws are not too deep. Prop turns freely. Some play on the strut, although I will recheck that.

better check it again. sounds like the prob. even if they are rubbing turning the motor by hand wont tell you. The bolts that come with xl motor are too long at least in my boat. I had to cut them about in half.

[electric]

ok, I wil try cutting down the bolts and also increasing the gap on the prop to the strut.