I bought a flylens75 last week with 2x 720mahGNBLiHV  and 2x 550mahGNBLiHV.

For some reason when I use both the 720mahGNBLiHV the drone keeps flying upwards and does not stop or respond to throttle so I have to disarm.

both the 550mah works perfectly with no problem. 

I thought this could be a PID problem so I added 5 grams of weight on top of the drone when the 550mah is plugged in to match the same weight of the 720mah and there is no problem in doing this, the drone flies perfectly normal.

The problem is only happening when using the 720mah. 

The weird thing is, is that I did manage to have 4-5 good flights with no problems with the 720 mah lihvs before this problem started happening. 

never seen this problem before, can someone confirm this is a bad batch of lihv's? could it have caused damage to the motors/FC ? 

Do you use a capacitator?
I would add one and give it a try

It shouldnt be a bad batch of battery causing a flyaway.
Check frame stiffness
Any loosen vibrating part?

More weight can cause more vibrations and noise, if there comes additional noise from somewhere else it can come to a flyaway.
Your first flights without issue does point on the direction of hadware related noise.

Change rotors as first step if you didnt allready, bad props can cause excessive noise.

I agree with Hug, unlikely to be the Lipo.

Dirty power + ICM42688 gyro is more likely the issue. Throw a 10V 100uf or 470uf cap on it and reassess. Also tighten down every screw, within reason.

I do think 720mAh is a bit heavy for a 75mm. i personally wouldn't run more than 450mAh on a 75mm, maybe 550mAh at a push, but 720mAh is too big and heavy IMO.

(01-May-2024, 10:51 PM)hugnosed_bat Wrote: Do you use a capacitator?
I would add one and give it a try

It shouldnt be a bad batch of battery causing a flyaway.
Check frame stiffness
Any loosen vibrating part?

More weight can cause more vibrations and noise, if there comes additional noise from somewhere else it can come to a flyaway.
Your first flights without issue does point on the direction of hadware related noise.

Change rotors as first step if you didnt allready, bad props can cause excessive noise.

This is a pre-built flylens75, capacitor is on no bad solders, no loose screws frames perfectly intact.

I explained, I added 5g of weight to the 550mah battery which mimics the weight of a 720mah and there is no problem. The problem ONLY happens when I fly with the 720mah's

props are perfect, quad has taken extremely light knocks. this is a brand new flylens75

There's really no way a battery should produce messy gyro data or runaway PIDs. They just push electrons through all your circuits. It's like a spring on a wind-up toy.

Could you check the batteries with a multimeter. Just wondering if the cells are showing vastly different voltages. Can't see why it would make a massive difference, but if it is basically acting more like a 1S Lipo, then maybe that could be an issue.

Personally though, i'd drop them to storage charge, and throw them in your battery box for a rainy day when you have a different quad to try them with. If the others work fine, then go with them. I wouldn't over think it. If something doesn't work, then don't use it.

If you can get them, then Tattu Lipos are better in terms of quality, but more expensive. CNHL are super cheap, but you don't get as much flight time out of them. I've had no issues with any of the GNB I bought, but others on here refuse to use them. I fly all three of those brands without issue.

Yes, that is a weird problem. People above have mentioned frame vibrations. One easy thing to try is to increase the rpm filtering. Try going from 1.0 to 0.8. That has fixed fly-away problems I had with a couple 2S builds on too-flexible frames.

Flylens uses a TPU battery holder that twists and slides in place. It does not stay on very well, so you may want to check that it is secure and has not slid to a loose position. It comes in two sizes, the wide one may be too loose for the GNB 720s.

A slippering battery can cause a lot vibrations too.

720mah would be able to provide more energy, more noise from there could be it too, it would need decreased pid values - iterm windup is what causes flyaways.
To high iterm or antigravity value - or to much noise does cause a flyaway.

As it already has a capacitator, i would also suggest segler999 s suggestion for the filterslider, increased gyro filtering.

The only chance i see for an issue on the battery would be bad conductivity, that would should produce heat.
If the connector of the battery does smell and gets hot after flight - maybe we should aim the battery itself. I believe its unlikely.

Did you mount a fresh set of rotors?

I have had similar when using a HV cell or pack on an older FC board that just could not cope with the extra power available from the HV battery. Same could occur with a combination of FC settings pushing the thing close to runaway.

THIS issue is easy to check for. Reduce one of the 720's to around 3.9v, run it down on another quad, storage charge it and stop that at 3.9v per cell, etc, and try to fly that.

From my several times over experience its likely to fly OK once the "top" is off the pack.

You just have a set up that's at limit.

(03-May-2024, 07:12 AM)BadRaven Wrote: I have had similar when using a HV cell or pack on an older FC board that just could not cope with the extra power available from the HV battery. Same could occur with a combination of FC settings pushing the thing close to runaway.

THIS issue is easy to check for.  Reduce one of the 720's to around 3.9v, run it down on another quad, storage charge it and stop that at 3.9v per cell, etc, and try to fly that.

From my several times over experience its likely to fly OK once the "top" is off the pack.

You just have a set up that's at limit.

Yeah you're right, I can fly at a lower voltage with the 720's even though I still get oscillation's, sometimes I can fly at full charge and only get oscillation's, I think the more I test the 720 packs the more likely it is to behave like in the picture and fly away unless I disarm. I have sent a email to flywoo explaining the problem which I can already guarentee theyre gunna tell me to only use their packs (in which I have already ordered some) or maybe not to use LiHV packs atall. Even if changing some of the FC settings would fix this problem, im not going to as the settings have been specifically tuned for the frame. I just didnt think that a pack would have such an effect so I get why people are saying it's loose screws etc.

I have never had an issue with using the full charged voltage of LiHV packs over LiPo packs. I don't think that is the problem. I think frame vibration from the motors is the problem.

Since it is a VERY EASY experiment, go into BF, in the PID tuning tab, try sliding both rpm filtering sliders from 1.0 to 0.8. Don't change anything else. If this solves your problem, great. If it does not, it is no biggie to slide the rpm filtering sliders back to 1.0 and continue troubleshooting.

Im with segler for the suggestion of short filter changes.

What does it mean when one battery doesnt and the other one not, its a huge performance difference.
We can say the gnb720 are much stronger than your gnb550mah.

As flywoo suggest 720mah as size for that quad, it does mean flywoo did tune it for bad batteries.
That might not realy be what you are looking for, we are allways looking for the best batteries, they are the bottleneck.
There are only bad reasons for that oscillation, no way does point to use their packs until you found a filterissue as source.

I would realy suggest to follow seglers suggestion, not to follow flywoos support - i dont expect much by them for the support of that issue.
Use only their lipos is a non acceptable suggestion, we commonly arent limited to lipobrands even not on prebuilded and tuned quads: we allways choose the best quality we get. I dont believe it would be their suggestion.

Its likely that flywoo batteries are rebranded gnbs - if so it would point in the direction of filter adjustements either.

Going to increase filters will bring you into troubleshooting and might make you ready for other issues in the future.
Prebuilded quads does work, but as crashes and damage is regular, ready to fly doesnt last long. Troubleshooting and rebuilding will come...

No fear to try, its the first step of knowledge and experience if you dive into betaflight filter adjustements :-)
We will support you, we need some informations to proceed. Filter adjustements would tell the direction to proceed.