Arrows Viper problem

[Tim Donald]

The other day I was flying my arrows viper on a 3s2200 Lipo and I suddenly lost all power but still had control for a dead stick.  I checked the battery which is in good condition, and tried again and it was fine.  Had a few more flights no problem.  Today on the second flight it did the same thing again.  The speed controller (original one) also starts bleeping (I think 3 times repeating).  I'm pretty sure this was with a different Lipo.  Anybody know what the problem is likely to be? 

 

Edited November 22, 2022 by Tim Donald

[SIMON CRAGG]

Sounds like the esc is on the way out.

 

I have experienced similar on one of my 90mm Jets.

 

IMHO its not worth risking it, so replaced the esc and fault free ever since 25+ flights.

[Andy Stephenson]

I had an early brushless speed controller that just stopped like this but when I looked into it, it had a temperature cut-out which was set way too sensitive so I replaced it with a resistor, job done.

[Shaun Walsh]

Could it be that the battery is marginal in terms of its ability to provide sufficient current without the voltage sagging to the point where the ESC low voltage cut off operates? Most likely to happen if the model is flown at high throttle for a while.

[Tim Donald]

It's possible but I've probably flown it 50+ times with the same batteries (I have about 10 the same and rotate them with each flight).  It has been a lot colder though.  I think I will change out the ESC and see how that goes.

[Shaun Walsh]

6 minutes ago, Tim Donald said:

It's possible but I've probably flown it 50+ times with the same batteries (I have about 10 the same and rotate them with each flight).  It has been a lot colder though.  I think I will change out the ESC and see how that goes.

Before you do that try bench testing, connect a voltage tester to the balance plug on the battery and run it at full throttle watching how the voltage sags. You could try it with a warm battery and a cold battery and compare them. You may even get it to cut out.

Edited November 22, 2022 by Shaun Walsh

[Tim Donald]

Good idea,  I will try it tomorrow.  Cheers.

[Frank Skilbeck]

Clubmate had loss of power on his electric Tundra the other day, 2 batteries went in quick succession, so he suspected the ESC, but using a battery checker we were able to see the battery voltage dropping off substantially under load. But it didn't cut out, but reduced the power to keep the battery above minimum volts, so it maybe it is your ESC.

 

I bought one of these years ago, rubbish discharger but great for checking battery voltages under load as you can see each cell voltage.

[Tim Donald]

Thanks Frank.  As luck would have it I just bought a watt meter that I haven't tried yet so will give it a go.

 

[john davidson 1]

The Arrows hawk probably uses the same esc, it looks tiny and my one gave up the ghost. Mind you this was after a few flights abusing it on 4 cells. Fun while it lasted!

[GrumpyGnome]

Three beeps repeating is lvc on this model........ check out the battery voltage under load.

[Andy48]

On 22/11/2022 at 17:09, Tim Donald said:

It's possible but I've probably flown it 50+ times with the same batteries (I have about 10 the same and rotate them with each flight).  It has been a lot colder though.  I think I will change out the ESC and see how that goes.

Could it be that the batteries are a lot colder too and the voltage is sagging quickly and thus cutting the ESC.

[Trevor]

And one more possibility - Is the battery/ESC connector good? Any resistance caused by a poor contact here will trigger the low voltage cutoff in the ESC. This would be consistent with the intermittent behaviour you are seeing. It would of course also be fixed by replacing the ESC 🙂

[Simon Chaddock]

"...but much colder" could be a clue. LiPo do not like the cold. Performance and available capacity starts to fall away below 8 Celsius. 

[Engine Doctor]

I had a Nigel Hawes Tucano built probably 9 or 10 years ago and flown regularly . Very fast as I upgraded it to a brushless set up with a 2850 KV motor running on 3 s Lipo.

The batteries I first bought for it lasted a few years but as they aged I noticed that the didn't like performing if they were cold and the problem gradually increased. If flown flat out the motor would cut out but stll had control . I found that by flying at a lower throttle for a while until the battery warmed a little they would give a decent flight time and performance . So suspect the cold as a possible culprit .

I think the little Tucano still lives as sold it at our club swap-meet earlier this year.

One more thing to check are the motor connections . The factory soldered bullet connectors had to be re soldered due to dry joints . Symptoms were motor would sometimes hesitate when starting and might take 2 or 3 goes to get it to spin up. 

Edited November 24, 2022 by Engine Doctor

[Tim A]

Friend of mine had the same issue in an Arrows T33 very occasionally would exhibit an uncommanded dive or climb and on landing the gyro would indicate low battery by beeping and rapid flashing of the LED. Changed ESC, battery to no avail. Walking back to the pits he head a servo twitching, turned out the elevator servo was faulty replaced it, problem solved. I also have the T33 and Hawk and the low battery indicator has been on after landing but the batteries have tested fine above 60% after a short two minute flight. I normally get 4 mins. out of theT33 and 3.5 mins from Hawk.