T-rex 250 suddenly dies when flying in idle up.

[TR450ZS]

Oh dear, sorry to hear you are still having the same issue. Have you tried with a new Lipo? perhaps the cold weather you have is having adverse effect on your Lipos?
And as Snakes SA said, check your SAT connection.

[myxiplx]

The Talon 15 manual has some error codes at the back, I'd try spooling up on the ground and see if you can trigger this and look at the specific error code its seeing, it might take some guesswork out.

I'm also wondering about whether you're hitting a low voltage cutout from the transition to idle up. Do you have any way to check the IR of your packs, or could your packs be cold?

If it happens consistently on switching to IU, then I would suspect a current draw or possibly FBL problem rather than a loose wire.

[pgoelz]

Originally Posted by Bergersen

The only thing that happened when i changed to the Talon is that the "shut down" now
happens "in order" just 2-4 sec after i hit idle up.

- I can fly around in normal mode and everything works fine.

- As soon as i hit idle up, it flies for about 2-4 sec and then shuts the motor off. Everything else works.

- As soon as the heli lands, i can hear the esc reset (beeping) and then its ready to go again.

- Then i try again and the same happens.

- But now comes the strange part. When this has happened 1-2 times, then suddenly
everything works fine and i can fly the rest of the batteri in idle up without any problems

Since many of us are using the Talon 15 on 250s, it is unlikely there is anything wrong generically with your ESC choice. In fact, I am flying a Talon 15 on my scale 250 that is about 150 grams heavier than the usual 250 with no issues at all.

So..... my best guess would be that the ESC is shutting down due to high motor current or low battery voltage.

1. How do you have the overcurrent shutdown set?

1A. Ditto for low battery detect / shutdown. I believe mine is set to soft cutoff. I don't know how it behaves if it is set to hard cutoff.... it might shut down on a low voltage spike that would be ignored otherwise.

2. Do you know what your head speed is? If your head speed is too low, you will be flying at a less efficient collective pitch and this could cause the motor current to be higher than normal. For comparison, I fly my (heavy) scale 250 at 3600RPM and get easy 5 minute flights to 30% on 1000mAH Nanotechs. My pod and boom 250 flies at about 3200RPM and gets easy 5 minute flights to 40% on 850mAH Pulse packs.

3. What pinion are you using? If the pinion is too large and the head speed is too low, this also could cause the motor current to be higher than normal.

4. If you are in governor mode, try flying in non-governor mode with a throttle curve and see what throttle setting you need to hover at your chosen head speed. Values below 60% or above 80% would be suspect, to me anyway. If you are hovering below 60% throttle, I would suspect that your gearing or head speed were inappropriate. If you are hovering above 80%, I would suspect that your head speed was excessive and you were wasting too much power.

5. Are you absolutely CERTAIN that your batteries are healthy? Abused batteries will develop high internal resistance and will check OK on a charger or battery checker but the voltage will sag under load. This will cause the ESC to detect low battery and shut the motor off prematurely. Back on the ground, the battery will check OK. As myxiplx suggested, check the error codes and see if you can determine WHY the ESC shut down.

6. One other possibility if you have a belt drive tail would be tail belt static. Try spraying your tail belt with silicon spray or Armor All.

Paul

[Bergersen]

I am using brand new Turnigy Nano Tech 3cell 850mah 25-50C batteries. I got 5 of them and the have only been charged 3 times so they should be fine. Bought them 3 weeks ago. Im also using the stock align batteries with the same results.

The battery temp should be fine. I store them in the house (+22 C) and outside temp is around +1 C.

Yesterday i took the whole heli appart and checked every clerance/ballbearing ect. but it
still shut down.

Off course i didnt think to check the error code on the esc, but i did today.

The code i get is: Over-current

I went outside and increased the idle up throttle from 90% to 95%, to see if it shuts
down faster. But now it works?!? I have flow 4 batteries in idle up without shutting
down. Tried to decrease to 90% again, and then it shuts down with the over-current code.

Wtf?


I dont use governor mode. And the head speed/pitch etc. i dont know. Bought this as a RTF heli so i dont have any gauges yet. Im using the stock 15T main gear and it has the torque tube to the tail.

Here is a link to the heli: http://www.helipal.com/trex-250-plus-dfc-rtf.html

[pgoelz]

Originally Posted by Bergersen

I went outside and increased the idle up throttle from 90% to 95%, to see if it shuts down faster. But now it works?!? I have flow 4 batteries in idle up without shutting down. Tried to decrease to 90% again, and then it shuts down with the over-current code.

I know some people fly at very high straight line throttle settings but for sport flying that is VERY high and with a 15T pinion could result in an excessively high head speed. As the head speed increases, the power lost to drag increases very rapidly (is it a squared function). The increased power required to hover could tip you over the 15A limit. If you are over the limit at 95% throttle, the higher efficiency at 100% throttle (where the ESC is full on and not PWMing the output) could put you just under it.

Try reducing the throttle to something in the high mid to 70s and see how it flies. On my heli, that results in around 3600RPM and is MORE than adequate for sport flying.

Note that at lower throttle settings, you really should program a proper throttle curve that matches motor power to collective settings unless you are running a governor. Without a proper throttle curve, the head seed will vary with pitch and make the collective response less predictable. But even with a straight line "curve" in the 70s, you should at least be able to fly and you should not get overcurrent shutdowns.

You really should get some instrumentation. While it is certainly possible to set up a heli without measuring anything, it is a lot more difficult. And when you run into trouble like you have, you are left guessing what the trouble is. A pitch gauge and a simple airplane tach would be good starters. A current meter that can be inserted between the battery and the ESC would also be valuable. With those three instruments, you would know if you had a reasonable head speed and were hovering at an appropriate pitch. You would also be able to see what your actual current was.

Note that you can do without the tach in a pinch. If a head speed of 3600 suits your flying, you can easily observe a stationary shadow on your rotor at 3600 if you spool up under fluorescent lighting. I find 3600 is a suitable sport flying head speed on a wide range of small helis.

Paul

[myxiplx]

Hmm, a few people have said they've hit over current on the talon 15. I run a 16t pinion and either 4200 or 4500 rpm governed with mine though, so with a 15t pinion it really should handle it.

It might be worth trying governor mode and see if its any smoother spooling up between the headspeeds.

Also, see if you have any binding anywhere in the gear chain. I've heard of belts too tight causing strain on the motor and high current draw in the past. Gear mesh or bearing issues could also have a similar effect.

Failing that, with the castle software you can disable the overcurrent protection. There's always going to be a little risk to doing that, but several people have made that change in the past without ill effects.

[Murph_d]

Originally Posted by myxiplx

Failing that, with the castle software you can disable the overcurrent protection. There's always going to be a little risk to doing that, but several people have made that change in the past without ill effects.

More than several people. If you do a good search through this forum, you'll see this issue over and over. I don't know why but for many Talon 15 users, it's practically SOP. Supposedly, it voids the manufacturer warranty, so what, it works. Disable the overcurrent protection and don't look back.

[TR450ZS]

I did nkt even bother to see about the over current on my 250, when I fitted the Talon 15 I immediately disabled to over current, as said the previous lost it is almost SOP on a 250. I also went staight in with gov settings on std pinion. I have the 16t on hand but for my flying style the 15t is perfect.
what charger are you using on your lipos?

[Bergersen]

Originally Posted by pgoelz

I know some people fly at very high straight line throttle settings but for sport flying that is VERY high and with a 15T pinion could result in an excessively high head speed. As the head speed increases, the power lost to drag increases very rapidly (is it a squared function). The increased power required to hover could tip you over the 15A limit. If you are over the limit at 95% throttle, the higher efficiency at 100% throttle (where the ESC is full on and not PWMing the output) could put you just under it.

Try reducing the throttle to something in the high mid to 70s and see how it flies. On my heli, that results in around 3600RPM and is MORE than adequate for sport flying.

Note that at lower throttle settings, you really should program a proper throttle curve that matches motor power to collective settings unless you are running a governor. Without a proper throttle curve, the head seed will vary with pitch and make the collective response less predictable. But even with a straight line "curve" in the 70s, you should at least be able to fly and you should not get overcurrent shutdowns.

You really should get some instrumentation. While it is certainly possible to set up a heli without measuring anything, it is a lot more difficult. And when you run into trouble like you have, you are left guessing what the trouble is. A pitch gauge and a simple airplane tach would be good starters. A current meter that can be inserted between the battery and the ESC would also be valuable. With those three instruments, you would know if you had a reasonable head speed and were hovering at an appropriate pitch. You would also be able to see what your actual current was.

Note that you can do without the tach in a pinch. If a head speed of 3600 suits your flying, you can easily observe a stationary shadow on your rotor at 3600 if you spool up under fluorescent lighting. I find 3600 is a suitable sport flying head speed on a wide range of small helis.

Paul

Thanks, im starting to get it now I will test with different throttle settings. I have ordered the intsruments, so ill check the pitch, rpm and so on when i get them.
Im am going to upgrade to a 450L Dominator or the Goblin 380 kit, so i will need the instruments anyway

Originally Posted by myxiplx

Hmm, a few people have said they've hit over current on the talon 15. I run a 16t pinion and either 4200 or 4500 rpm governed with mine though, so with a 15t pinion it really should handle it.

It might be worth trying governor mode and see if its any smoother spooling up between the headspeeds.

Also, see if you have any binding anywhere in the gear chain. I've heard of belts too tight causing strain on the motor and high current draw in the past. Gear mesh or bearing issues could also have a similar effect.

Failing that, with the castle software you can disable the overcurrent protection. There's always going to be a little risk to doing that, but several people have made that change in the past without ill effects.

Originally Posted by Murph_d

More than several people. If you do a good search through this forum, you'll see this issue over and over. I don't know why but for many Talon 15 users, it's practically SOP. Supposedly, it voids the manufacturer warranty, so what, it works. Disable the overcurrent protection and don't look back.

In other words, i should have bought the Talon 25 But ill test with gov mode and disable the overcurrent protection.

Originally Posted by TR450ZS

I did nkt even bother to see about the over current on my 250, when I fitted the Talon 15 I immediately disabled to over current, as said the previous lost it is almost SOP on a 250. I also went staight in with gov settings on std pinion. I have the 16t on hand but for my flying style the 15t is perfect.
what charger are you using on your lipos?

Is it possible to disable the over current with stick prog. or do i need the Castlelink?
(i know i should have bought the castle link at the same time)

Im using a SkyRc Quattro B6AC charger.

[pgoelz]

Originally Posted by Bergersen

In other words, i should have bought the Talon 25 But ill test with gov mode and disable the overcurrent protection.

Not necessarily. It depends on your head speed and flying style. I am using a Talon 15 in two different 250s with no issues at all. One is a scale ship that is way heavier than yours. I think it weighs around 450 grams AUW. However, I keep the head speed down on both. The scale ship flies at 3600RPM (about 75% throttle at hover) in governor mode, which is PLENTY even at that weight. The pod and boom ship flies at about 3200RPM (maybe 70% throttle in a hover) also in governor mode. Neither has ever hit overcurrent shutdown even in pitch pumps. That said, I don't fly 3D so I may not be stressing things as much as some.

My best guess is that your head speed is excessive or your gearing is way off for the KV of your motor. Tach your head speed and see what it is. Unless you are doing 3D, try flying somewhere between 3200 and 3600 RPM and see how it goes.

Paul

[myxiplx]

The thing is, we have people running that Talon 15 in a heavy scale bird with low headspeed, and I'm running it on a light 3D bird with high headspeed.

For you to be getting an over current warning on the Talon after getting shutdowns on another system makes me wonder if something is wrong.

I would be very tempted to strap the heli down and do some bench testing to see if you have an issue somewhere. I would suggest:
- test with no blades
- test with main blades only
- disconnect tail mechanism and test main blades only

[Bergersen]

Thanks for the tips guys, but now i think i found the problem...

I bought the Castlelink and found out that my esc was missing a couple of updates. Updated to the latest (4.22?) and now it works fine. I have flown around 10 batteries and not a single shutdown

Im using a flat 95% throttle curve and 12% pitch in idle up.

[pgoelz]

Originally Posted by Bergersen

Thanks for the tips guys, but now i think i found the problem...

I bought the Castlelink and found out that my esc was missing a couple of updates. Updated to the latest (4.22?) and now it works fine. I have flown around 10 batteries and not a single shutdown

Im using a flat 95% throttle curve and 12% pitch in idle up.

Damn, its always the one thing we didn't think of

As an aside.... to the folks that suggest that overcurrent shutdowns could be caused by a bad bearing or binding somewhere, I say "possible but unlikely". If you think about it, for every one amp of excess current draw in flight due to binding or a bad bearing, that equates to around 11 watts of power being dissipated by that component (power is current multiplied by voltage). So the power dissipated by a bad bearing or something binding would likely melt the offending component fairly quickly even if it was only responsible for a couple amps excessive current draw.

I'll put my Whattmeter on my 250 one of these days and see what it draws in a hover as well as in a full collective pitch pump and report back. But I suspect it is nowhere near 15A, at least on my relatively low head speed birds.

Paul