Haven't seen a definitive answer on this - BEC current backflow

[Mike680]

Is it okay or not to run a backup power supply like the Optipower Ultraguard with any Hobbywing ESC with an internal BEC? Can it harm the internal BEC? Will the internal BEC allow current from the Ultraguard to back flow through it and try to power the motor thereby pulling huge current loads and frying equipment? Is there reverse current diode type protection built into the Hobbywing internal BECs?

These are very important questions and they're being debated right now in the Ultraguard thread on the main page. We need answers from people in the know. As far as I'm concerned, this topic needs to stay at the top of this sub-forum until it is put to bed one way or the other since it directly relates to all internal BEC equipped Hobbywing ESCs. Thanks.

[myxiplx]

I agree. It seems that low voltages (under 5v) are fine, but that's only based on the fact that a few of us have tried that without problems.

High voltages definitely do fry the ESCs, but with the amount of products available now to provide backup for the BEC we really need to know what it safe.

There's the Scorpion backup guard, the Optipower Ultraguard, the R2 buffer pack. They're all good products, but we don't know if they can be safely used with a HobbyWing ESC.

[Mike680]

Originally Posted by myxiplx

I agree. It seems that low voltages (under 5v) are fine, but that's only based on the fact that a few of us have tried that without problems.

Low voltage is one thing, but what about when a flight battery comes unplugged, connector de-solders itself, etc? The backup power supply picks up the load and, apparently, some internal BEC equipped ESCs (Hobbywing was specifically mentioned) will allow the motor to start to run and pull massive amounts of current from the backup power supply through the FBL/RX, throttle/BEC leads and straight through the internal BEC? From what they've said, it happens fast and things get very HOT very quickly. We definitely need to know these answers.

Backup power supplies have been around for a long time and ESC manufacturers should have gotten on board with their use a long time ago. Simple reverse current diode protection in the BECs would have solved it.

[DarkSyd3D]

I've been running 4 helis all on the internal BEC set to 8v and all on the optiguard since the release of the 160. Actually ran it on a 100 v3 for about a year prior and zero issues. I always disconnect the flight pack first then disarm the optiguard. Again, zero issues doing it this way. Done on spartan fbl

[Chrsmn]

I run almost a year an optipower guard with Hobbywing 160V4 with no issues.....

[cycled]

I've had the same experience with the separate UBEC (7.4V, R2 buffer, battery always unplugged first). Still, having an official word on use of HW BECs with backup power solutions would be great.

[myxiplx]

Originally Posted by cycled

I've had the same experience with the separate UBEC (7.4V, R2 buffer, battery always unplugged first). Still, having an official word on use of HW BECs with backup power solutions would be great.

Exactly. I would like to know categorically what is, and what isn't safe, and then I can make an informed decision on what I want to run.

If there's a risk of powering the motor back through the BEC then fair enough. If that can only happen if the ESC fails that's probably a pretty low risk. It may be that there isnt a realistic failure mode where the ESC dies but that circuit remains active. I really don't mind either way, I'd just like to know the facts.

[Chrsmn]

The backup buffer for sure works with Hobbywing esc
It helps the bec during high loads of servos.
and helps to have constant power to servos.
for sure it works with HW
All other risks that can happen are the same with all escs

[Mike680]

Originally Posted by DarkSyd3D

I've been running 4 helis all on the internal BEC set to 8v and all on the optiguard since the release of the 160. Actually ran it on a 100 v3 for about a year prior and zero issues. I always disconnect the flight pack first then disarm the optiguard. Again, zero issues doing it this way. Done on spartan fbl

Good to hear. I wanted to replace the hot running Castle 120HV w/ Castle 20A external BEC on my 550 with a HW 120. I was having doubts about it after reading about the current backflow problem. You've never had the Ultraguard try to run the motor back through the internal BEC with no flight pack plugged in?

[Theunisjr]

I have also been runnig the 100v3 on my logo 550sx for 90 flights and no issues. I always unplug the Flight battery first then disarm the Optigaurd.

[Mike680]

Originally Posted by myxiplx

If that can only happen if the ESC fails that's probably a pretty low risk.

That's not the only way. It could happen if the main flight pack comes unplugged or a solder joint fails by de-soldering itself or something.

And, even if it were the only way, that's still not acceptable. I don't want my FBL and or RX to also burn up causing me to lose all control when I'm coming down in the auto because the ESC failed and the motor quit. Talk about adding insult to injury.

[Mike680]

Originally Posted by cycled

I've had the same experience with the separate UBEC (7.4V, R2 buffer, battery always unplugged first). Still, having an official word on use of HW BECs with backup power solutions would be great.

Yes, let's keep this at the top until we get a definitive answer from the source.

[Fauropitotto]

Originally Posted by myxiplx

Exactly. I would like to know categorically what is, and what isn't safe, and then I can make an informed decision on what I want to run.

If there's a risk of powering the motor back through the BEC then fair enough. If that can only happen if the ESC fails that's probably a pretty low risk. It may be that there isnt a realistic failure mode where the ESC dies but that circuit remains active. I really don't mind either way, I'd just like to know the facts.

I've had an EC5 unsolder itself in flight before.

For what it's worth, I started to panic after reading these threads so I just tested this on the 160v4.

Running the R2 Supercapacitor buffer cap plugged into my Ikon which was fed by my ESC BEC. I powered up the entire system with my regular 14S flight packs as if I was ready to fly. Then I disconnected the flight packs, and as expected, the BEC was still being back fed power by the R2 supercap backup. I know this because the ESC fan was still running, and I can plug in the program box and change settings.

Then I tried to turn on the motor the way I normally do. Nothing happened.

I do not know how the ESC is designed, but it did not appear possible to start the motor off of the backup unit. Perhaps there are schottky diodes built into the unit between the BEC circuits and the ESC for exactly this possibility.

I too am hoping for an official answer from HW.

[Mike680]

Originally Posted by Fauropitotto

Perhaps there are schottky diodes built into the unit between the BEC circuits and the ESC for exactly this possibility.

Hope so.

I too am hoping for an official answer from HW.

Exactly.

[Mike680]

Here's someone experiencing this exact issue with an Ultraguard and a HW ESC.

https://www.helifreak.com/showpost.p...&postcount=645

Now, what I'm wondering is if just "throttle tones" could draw enough current back through everything to be damaging. It doesn't sound like it was actually trying to run the motor, rather just blip it for tones. Another poster reported that his iKON FBL unit got very hot very quickly, but I can't remember what ESC he was using.

[echopoint]

Originally Posted by Mike680

Here's someone experiencing this exact issue with an Ultraguard and a HW ESC.

https://www.helifreak.com/showpost.p...&postcount=645

Now, what I'm wondering is if just "throttle tones" could draw enough current back through everything to be damaging. It doesn't sound like it was actually trying to run the motor, rather just blip it for tones. Another poster reported that his iKON FBL unit got very hot very quickly, but I can't remember what ESC he was using.

He is getting throttle tones because his transmitter is off. The beeping proves that he is getting back flow current. If he was to turn on his transmitter, and increase his throttle, he would indeed see the esc try to pull current from the backup battery to run the motor. This would potentially damage his battery and ESC.

I am glad to hear that people are not seeing this issue with the V4's, but I certainly see it with my HW v3 100A ESC.

[Mike680]

I just ordered a Platinum 120A V4 ESC. I like my HW Platinum 60A V4 ESCs that much. I'll post here about this "back running" of the motor whether it happens or not with the Ultraguard when I get it and everything's installed.

[DarkSyd3D]

Originally Posted by Mike680

Yes, let's keep this at the top until we get a definitive answer from the source.

The only definitive answer you're going to get from the source is by emailing them. support-us5@hobbywing.com
And if you don't get a satisfactory answer than to have peace of mind over it just get the Optipower BEC guard

[cycled]

Originally Posted by DarkSyd3D

And if you don't get a satisfactory answer than to have peace of mind over it just get the Optipower BEC guard

Or probably two, since as pointed out in the other thread, multiple plugs are needed for current sharing. Or Schottky diodes. But this thread isn't about work-arounds, it's whether the BECs themselves are protected.

BTW, is the separate 10A UBEC equivalent to what's in the bigger v3 ESCs, or the v4, or something completely different?

[Mike680]

Originally Posted by DarkSyd3D

The only definitive answer you're going to get from the source is by emailing them. supportus5@hobbywing.com

Apparently, they don't respond to emails with any substance. And, that's a problem in and of itself. Besides, they need to have an official presence here.