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[boat captain]

Hi


I have fitted 2 of these on trying them in the boat on our lake, she started off at a realistic speed for about 20 seconds and suddenly slowed down to about half that speed.  Any ideas to what is the problem?


Regards
Joe

[malcolmfrary]

From the very last item on the instructions - https://cdn-global-hk.hobbyking.com/media/file/997648571X26327X52.pdf - it says that there is "overheat protection".  Doesn't say whether it shuts down completely or goes into a limp mode.

[JimG]

You need to check the current taken by the motor under load. Connect a watt meter between the battery and esc and run the motor in  the pond while it is restrained. The measured current will be higher than when free running  but will show if the currrent is too high for the esc. Another way of checking is to fit a smaller propellor and see if that cures this.
Jim

[boat captain]

I tried as sugested and the amperage was 4.8 with a 8.4 3300 nimh battery.  Any other ideas?

[chas]

Continue with the testing, using the watt meter, but Check what the battery voltage is when the motors start to slow. You can also try running the model with just one motor and ESC working, a longer run time at full speed will rule out an ESC fault.
   Telling us what the motors and propellers are will be a help too.

[boat captain]

 The motors are Turnigy 1200kv 150watt props Prop Shop 3 blade 13/15.
 
Was at the lake today boat started fine after 20 seconds slowed down. A mate who is well up on brushless and I got her on the bench disconected the batteries reconected them and they ran at normal full speed for 10 seconds, back in the water she slowed yet again back to the bench, disconected the batteries reconected them and run her on the bench at full speed after about 20 second they slowed down.  The batteries were reading 9.1 volt.

[malcolmfrary]

Risking a silly question, but everything that should be mechanically free is, isn't it?  Lock nuts that are not as locked as expected can create havoc when they wind themselves tight against the shaft bushes.

[JimG]

The motors are Turnigy 1200kv 150watt props Prop Shop 3 blade 13/15.
 
Was at the lake today boat started fine after 20 seconds slowed down. A mate who is well up on brushless and I got her on the bench disconected the batteries reconected them and they ran at normal full speed for 10 seconds, back in the water she slowed yet again back to the bench, disconected the batteries reconected them and run her on the bench at full speed after about 20 second they slowed down.  The batteries were reading 9.1 volt.

Beginning to sound like the batteries are past their best. WHen you checked their voltage was it when the motor was running or stopped. Low capacity batteries will drop their voltage under load when the motor is running but will recover temporarily when there is no load. If one of the cells in the pack is bad it will drop the total voltage to the motor reducing the speed. Letting it sit can allow the cell to get back to its original voltage only to drop again under load. Have you checked it with a different battery? If it still does this then more likely the esc is faulty.
Jim

[chas]

Just what JimG said, run the voltage test with the boat in the water, taking readings on the bench tells you very little. The battery is by far the most likely culprit, the chances of 2 ESC s misbehaving in an identical way is very remote. I presume your set up is one battery, to 2 ESC s with both ESC s connected by a Y lead to the receiver. If you try the boat with only one motor running, and get a better run time, you will know exactly what the problem is. One motor - half the load on the battery.
Charles

[boat captain]

The shafts are as they should be nice and free.


Each motor has it's own battery supplying it.


 I have run the batteries on a treble 5 motor for 12 minutes with no significant drop of voltage.

[chas]

Free running any of the 555 motors won't tell you anything, they typically draw around 1 amp like that.
  I suggest you follow the on load tests.

[boat captain]

Problem solved batteries fine, shafts not tight, speed controllers faulty.

[NickelBelter]

Interesting... what was the problem with them?  Improper set up?

[imsinking]

Problem solved batteries fine, shafts not tight, speed controllers faulty.

A normal brushless ESC is set to LIPO battery's from default which will be cell protection, go below 3.4v & it cuts the power , if your using Nihm's you need to reset the ESC to NO PROTECTION , as the ESC thinks the battery is not producing the voltage , a LIPO delivers all the amps required so needs protecting ( a lo cell alarm is a must) while Nihm's dont deliver power quickly enough.
You can reset the ESC using the ' beeps' but I couldn't make head nor tail of those , so I got a setting card . 
Bill

[boat captain]

I tried setting them with my card it would not light up thinking it was faulty tried with a mates card same result. Tried the cards on another speed controller both lit up.