I'm having an Identity Crisis

[Gary Manuel]

A member of our club joined the masses and like many of our members, bought himself a Hobbyking Bixler as a "chuck in the car and go" model. It's not his sort of model really - he's more into warbirds. To stamp his mark on it though, he gave it a proper camouflage spray job and it came out looking rather nice. I think he flew it half a dozen times maximum before deciding to sell it.

Owner number 2 decided to add LED lights to allow him to join in the night flying events we occasionally enjoy. It flew OK with the added LEDs and everything looked to be going well. About 5 minutes into the flight though, the motor started "pulsing" as though it was trying to tell him something, so he landed pretty smartish. My instant thought was that this was either a low battery voltage warning or maybe an overheating warning. Either way, it seemed to me to be a "feature" rather than a "fault". The battery voltage was 50% (ish) as I recall. He has flown it a few more times and it has done the same pulsing after about 5 minutes every time. I have a similar model and regularly get 10 minutes flight out of it. I offered to have a look at it for him to see if I could find out what was going on and see if I could get longer flight times out of it.

The problem is that there are no markings on either side of the ESC. I've also looked at many ESC manuals at home and on-line to find a model with similar behaviour. The nearest I've found is some larger e-flite ESC's have low voltage cutoff which can be set to pulse. The setup beeps are different though, so I'm pretty sure it's not one of them.

So here I am, asking if anyone out there recognises this particular ESC make / model and can point me to a manual that will help me understand the programming and the meaning of the beep tones.

The video below shows the motor pulsing, what the ESC looks like and what the NORMAL and SETUP tones sound like.

[Piers Bowlan]

Don't know what the ESC is but have you tried the motor with the LED lights disconnected and does it still pulse after a while? Have you tried plugging in another ESC for comparison. Have you tried another LiPo? Like you say, it is probably the ESC but it might be worth checking a few things first.

[Gary Manuel]

It still does it with lights off. I can't really change the ESC because the ESC and wiring was embedded within the 2 fuselage halves when they were glued together.

I've still got some bench tests in mind to do, but knowing what make of ESC is fitted is the key to understanding what's going on I'm sure.

[Biggles' Elder Brother - Moderator]

I think you might struggle here Gary! There are so many Bixlers built I suspect that there isn't single "definative" ESC in them. Its quite possible that the firm that has the contract to produce the latest batch may well simply go into the market "for something suitable for that batch" - rather than a set make etc.

BEB

[Gary Manuel]

You might be right BEB. The ESC was "acquired" separate to the Bixler kit though - the first owner thinks he got it from Hobbyking but can't really remember. I have a number of different ESC's from Hobbyking, but they all just reduce or cut the motor output rather than pulsing.

The motor pulse is an unusual feature, so I'm hoping someone recognises it and can point me in the right direction.

[Denis Watkins]

2 things Gary. The whistling, high pitch scream is one of the magnets hitting the motor innard, caused by slight bent shaft. Now, there is no programme to pulse at half throttle to full, so it must be volts drop, likely caused by a bad connection, usually a connection we soldered. It is not so bad cutting the fuselage cleanly to split it and reassemble. You do not want to hear this, but the model needs opening up

[Cuban8]

I've experienced 'pulsing ' with an ESC a while back. I put it down to overheating as I had the unit in the fuz without too much airflow - it was an 80A unit running at about 80% capacity, so I shouldn't have been surprised really. Mounting it through an aperture in the fuz, so as to allow the airflow free range over the heatsink cured the pulsing.

Edited By Cuban8 on 06/01/2017 12:25:39

[Biggles' Elder Brother - Moderator]

If you Google "ESC Pulsing" this doesn't appear to be as rare a phenomina as you might think - plenty of reports of it? May be looking at them might throw upo a pattern or some common cause?

BEB

Edited By Biggles' Elder Brother - Moderator on 06/01/2017 14:51:58

[john stones 1 - Moderator]

When i saw the title and who wrote it, i thought "well nowt new there then"

Cut it out Gary, you'll not spoil the looks and i've a new ESC if you need one

John

[Gary Manuel]

I suspect I may finish up changing the ESC for him, but I am the sort of person who likes to understand what's causing the problem. I have a spare 40A one I can use if needed.

I've flattened about 6 batteries today and only had it "pulsing" once. All the other times, the ESC went into "proper" low voltage cutout, when the motor stopped and would not start again until throttle was pulled to the bottom and back up again. Looks like I can rule out programming of low voltage cuttout. It could still be temperature or overlaod protection though.

When it was pulsing, I took some cell voltage readings using my battery checker. The reading was steady at about 10.8v (well balanced at 3.6 v/cell). I'm going to try this again when I get time using a more responsive voltmeter and an oscilloscope to see what's actually happening. I want to rule out or otherwise that the speed controller is somehow going into a cycle of reducing the output power, which reduces the battery current, which increases the battery voltage, which then allows the ESC to go back into full power and the cycle starts again.

I'm pretty sure that there are no high resistance connectors because it runs just fine for the first 4 to 5 minutes. The whistling isn't as bad as it sounds. All the Bixlers at our club make a similar whistling sound.

Current is less than 17A on full throttle with a fully charged battery. I'm assuming the ESC is a 20A one as recommended by HK. It's not getting excessively warm.

PS I still haven't managed to find any ESC's with similar beep codes.