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electronic problems !!

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john melia 104/06/2013 19:17:17
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well it seems i have problems with either the electronics within the dolphin or the tx , i have an orange dsm2 6 channel receiver with satelite , a 40amp esc , and a 220kv motor turning a 6x4 prop .

everything has been fine until about 4 days ago , when i just lost all control , ie nothing moved when moving the sticks resulting in the dolphin heading for terra firma , this has now happened three times , evrything seems fine until about 3 or 4 mins into the flight then loss of control .

I've done a range check , which is fine no problems with that , but i noticed on a few occasions the led flashing on the receiver , but everything was working fine , i've also noticed a solid led on the reciever and again everything works fine !!! on first connecting the battery and after the usual set of beeps usually the receiver led is solid not flashing , but as i say even when it is flashing it still works fine.

i ran everything up on the bench and at this time the led was flashing but all control surfaces were working as they should , i then disconnected and reconnected and the led was flashing but again everything was working normal .

however i have now found that if i push the throttle to anything more than 3/4 the motor stops immediately , this happens both with the led flashing or solid , and as i say at the very beginning of opening the throttle the motor stutters and then spins up.

i am now rapidly losing all the confidence i have painstakenly gained while learning to fly . all batteries ( 3s 2200mah lipo) are fully charged and balanced

the motor esc and prop arrangement was recommended by hobbyking ..

any help greatly appreciated

john melia 104/06/2013 19:19:16
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the tx is a spectrum dx7s

John Privett04/06/2013 19:28:42
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Sounds to me like it could be low voltage to the receiver - maybe the ESC isn't quite up to the job of powering the rx and servos? What do others reckon?

john melia 104/06/2013 19:31:13
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don't know yet john you're the first to reply , the esc was very hot when i had everything running on the bench , the esc is 40amp and the motor was recommended to go with this esc , having said that the esc came with the model so it certainly wont be the best around

Tom Wright 204/06/2013 19:34:44
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3908 forum posts
297 photos

John.

Firstly it's most unlikely that a 220 KV motor will be fitted with a 6x4 prop ,I assume you meant 2200 KV ? . You now seem to have two problems with loss of control and the motor stopping at 3/4 throttle.

It is quite possible that both problems are caused by bec ,so substituting the esc would be my first course of action , and a though check of the lipo connectors as if there is a bad joint it could cause the the motor to stop as the current draw rises .

If the motor stutters on start up this could be a poor joint in one of the three motor wires , or the timing is incorrectly set , this assumes the motor is free turning with the lipo disconnected. Any sort of binding or a loose magnet could cause this problem .

Tom.

john melia 104/06/2013 19:46:35
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1770 forum posts
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yes tom i missed a 0 out its 2200kv , i'm going to order another esc , and in the meantime i will check all connections , seems strange though how it flies perfect for 3 or 4 mins and in some cases more than that with no problems , then all of a sudden nothing ?

the motor has just started to stutter and stop after the last crash , as has the 3/4 throttle problem , the motor was running fine it seemed , before tonights loss of control

John Privett04/06/2013 20:10:16
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243 photos

If the ESC is overheating it could be getting hotter and hotter for 3 or 4 minutes before reaching the point where it stops (or partially stops) working.

john melia 104/06/2013 20:12:26
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1770 forum posts
24 photos

ok john , yeah that could well be , as i say i'll order another esc and see what happens

Pete B - Moderator04/06/2013 20:17:00
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As others above have said, the issue probably lies with the ESC not being man enough for the set-up.

As the flight progresses, the demand on the battery is pulling down the voltage it can supply. The motor is stopping probably because the LVC (low voltage cutout) is cutting in when it detects the drop in volts - this is often programmable to give you the choice of full-cut or a slowing-down of the motor.

At the same time, it is running out of the ability to supply the BEC with sufficient volts to keep the Rx and servos running - that's why the Rx light is flashing - it is indicating a 'brown-out'.

If you are running the motor at full throttle for much of the flight, this will aggravate the situation.

However, whilst my tendency would be to replace the ESC with something more sturdy, it's worth looking at how you have the existing one installed in the model. The flat side of the ESC is the heatsink side - this should be exposed to a flow of air and not used a a convenient location for double-sided tape to stick the ESC to the fuselage side, tempting though it is.....smile

If the heatsink is covered in heatshrink, cut away a rectangle over the heatsink area and, as mentioned, make sure it is getting some cooling air to it. If you feel it is too well insulated within the fuselage, consider making an opening or two to encourage some ventilation.

Finally, give the setup a chance to cool off from time to time in flight if you're not already doing sowink 2

Pete

john melia 104/06/2013 20:26:30
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1770 forum posts
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thanks pete , i'm beginning to understand a bit , and yes i thought the flat side of the esc was for mounting so i put self adhesive velcro on and slapped to the inside of the fuselage , i'm going to get another esc though , is there any recommendations as to which one ? what about this one

**LINK**

Pete B - Moderator04/06/2013 20:36:48
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Moderator
7663 forum posts
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I'll offer myself up in expectation of being shot down by others, but personally, I wouldn't bother buying any linear-BEC ESC (see the spec) nowadays, with switching-BEC ESC's being not a lot more in price but hugely more reliable in operation, in my experience.

BRC list a switching BEC 40A in their 'Pro' range but if it was my money I'd spend it here. I've numerous Hobbywing ESC of different ratings and they have been very reliable in operation. The BRC/Robotbirds offering looks to me to be a re-badged version of the H/Wing anyway...smile

Pete

john melia 104/06/2013 20:41:06
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its just brc is only about 20 mins away from me , so i could go get one tomorrow , and after repairing the dolphin (yet again) i could try it out .

which one were you looking at on brc pete , sorry for being a pain but i hevent got a clue when it comes to esc's /becs

Pete B - Moderator04/06/2013 20:49:18
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This one, John. Full list of available ESC's here thumbs up

Pete

Steve Hargreaves - Moderator04/06/2013 20:54:18
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Have you access to a wattmeter John....do you know how much current your set up is drawing?
Pete B - Moderator04/06/2013 20:55:58
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Whilst you're there, John, if you are thinking of getting the Pro 40A, treat yourself to the appropriate programming card - it makes life SO much easier! teeth 2

This one will work with Hobbywing Pentium/Flyfun and some Turnigy ESC's, such as the Plush, too......

Pete

john melia 104/06/2013 20:58:36
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steve -- yes i have a wattmeter but because the motor is cutting out at 3,4 throttle i cant test it , or at least i dont think i can ? face 7

pete -- yes i will have a look at the programming card too thumbs up

Steve Hargreaves - Moderator04/06/2013 21:02:52
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Course you can.....connect it up & the wattmeter will record current & voltage from the moment you open the throttle.....it would be interesting to see what the numbers are just before it cuts out....
gliggsy04/06/2013 21:25:07
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103 forum posts
4 photos

Hi Fellas, one other thing that's not been mentioned, if there's a duff servo pulling more amps than it should and causing the BEC to overheat, a problem that I've encountered in the past. Worth a try, pull all servo leads from rx and re-connect one at a time checking temp on ESC after each one.......G

Paul Marsh04/06/2013 21:32:43
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4059 forum posts
1222 photos

I've had this before. Cured it by putting a capacitor on the spare rx channel. The BEC wasn't powerful enough and wriggling the sticks caused a rx brownout. OK now...

john melia 104/06/2013 21:48:17
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1770 forum posts
24 photos

ok now heres something that might be important , i went upstairs after leaving everything for over an hour , connected the wattmeter up and this time around the motor went to full power drawing 30.2 amps , the motor still stuttered at the very beginning though.

now after about 15 seconds at full power i shut it off , when going to full power again the motor cut out and started to stutter and jump , also it was very hot and i could smell it , the esc was also getting hot .

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