i used liquid electrical tape to seal mine

Where exactly did you put it? Could you send me a photo, please? Thanks a lot.

Hi, today I was out on a bike ride and I got caught in the rain. My LTWOO ER7 derailleur, which I bought at the end of August, stopped working. It says 0% battery even when I charge it. The battery was at 87% before the rain. If I plug it in, the green LED stays solid as if the battery was charged, but the app still says 0%. Also, when I press the button on the rear derailleur, it flashes red.
Here video: https://drive.google.com/file/d/1kcLbW77WTYrgERWvIhRLGujFNgEcgUR1/view
I've already contacted the seller 318 Bike Store, LTWOO support, and AliExpress support, but I don't expect any kind of support.
Has anyone had the same problem? I was hoping the issue would be solved with the v3 and ER7 versions, but apparently not....

Hi, I'm reviving this thread. The seller at 318 Bike Store had me do some testing these days. I sent all the videos, and now we're talking about him shipping me a replacement rear derailleur as soon as it arrives from ltwoo. Since I don't have an ER7, he'll send me an ER9, which he told me will work with ER7 levers. He'll also send me new cables. If it arrives and everything works, I think I'll use silicone to seal around the cables. The water could only have gotten in through there...
We'll see when it arrives, and I'll keep you updated.

I also tried it out on the road today for a 137km ride, and it's really cool. It even fixed a small rubbing I had before with the manual trim without touching anything else.

hi thx for the answers. btw rightnow im using 50-34 chainring.
In your opinion, will it work smoothly? Because the chain tension will automatically increase when shifting to the 34T sprocket, but I might only use the 34T chainring with the 34T sprocket combination for safety.

What chainring size do you use yourself?

Thank you.

I use 50-34

I'm updating the situation after some time. Since I installed the battery inside the seatpost with this, I haven't had any more disconnection issues.



I've only been able to use one because I have a D-shaped seatpost.
To "revive" the shifting, I did several tests, and it works both with a mini power bank and with a cell phone + USB-OTG + USBA to USBC.




The day before yesterday, I changed the brake pads and used Shimano L05A ones. To retract the pistons, I removed the screw on the lever side and inserted the cup. Once the pistons were retracted, I removed the cup and closed the system. I didn't have to bleed the system.



I then finally mounted the Shimano 105 11-34 cassette with a CN-HG701 chain. Shifting is perfect. I haven't changed the pulleys yet, as the shifting is excellent even with them. I'm keeping them aside for the future.

Something strange happened to me today. While I was riding, the gear shifter suddenly died. I thought I'd try plugging it into a charger. Luckily, there was a house along the road with some guys who had power and a charger. Given the bad experience, I bought a mini power bank to leave in my underseat bag.



The only thing I can think of is that I hit a big pothole shortly beforehand. Did the gear shifter go into "protection mode"?

It happened again today after about 70km, but I have two pieces of good news:
1) Found the root cause: I checked the seatpost and found that the battery cradle had actually fallen out of its position and was just dangling inside the frame. This movement clearly caused the micro-disconnection that triggered the BMS protection. I reinserted it as firmly as possible and managed to ride another 150km without a single issue, even on rough roads.
2) Emergency fix confirmed: The 'defibrillator' method works! I used a mini powerbank to give it a 1-second 'wake up' charge, and the system came back to life instantly.

Now I've just bought rubber ribbed Di2-style mounts. They should provide the necessary friction and damping to keep the battery cradle from sliding down the D-shaped seatpost.

To solve the mechanical issue, I decided to purchase ribbed rubber/silicone adapters instead of the rigid plastic ones.

The reason is simple: with my new, stiffer wheels and D-shaped seatpost, I believe the rigid plastic created excessive vibrations, causing the battery to slip. These silicone mounts act as a vibration dampener, absorbing the strongest impacts caused by potholes. This should hopefully also prevent the micro-disconnections that trigger the BMS's protection mode.

Another recommended step is to carefully place heat-shrink tubing around the 14500 batteries to prevent them from moving excessively.

Anyway, now that I think about it, the battery holder started giving me problems when I put the stiffer, higher profile wheels on the bike. Perhaps the increased vibrations caused the battery holder to fall off the seat post.

New Reply from Ltwoo:

If it is working normally now, the previous malfunction was most likely caused by a loose seatpost mounting bracket (on the frame) or a loose lithium battery mounting bracket inside the seatpost battery. Simply tighten the battery again.

My reply:

As I said in my previous email, I didn't touch the cables, brackets, etc.

I simply connected the USB-C charger and it worked again. As soon as I connected and disconnected the USB-C cable, the rear derailleur light came back on and it resumed communicating with both the Geoid CC700 Pro and the Ltwoo app on my phone.

If it were a wiring or connection issue, it shouldn't have worked without first reconnecting them correctly or just connecting a USB-C charging cable, I think. Is that correct?

Or are you telling me that there's a cable that's not connected properly or and that the derailleur control unit goes into protection mode, and to exit protection I have to connect the USB-C cable?

Just to understand where the problem lies, I like to understand things....

@pavlo.k have you had no more problems?

Since I like to "understand" things, I tried to ask LTWOO support for an explanation of the behavior.
My Question:
I have a Ltwoo ER7 derailleur with which I've ridden over 3,000 km. Something strange happened today. While I was riding, the derailleur died, showing no signs of life, everything was off, even when I pressed the rear derailleur buttons...
I thought about trying to connect it to a charger. After plugging it in and out (without doing anything else), the derailleur came back on and everything restarted perfectly.
The only thing that happened shortly before was that I hit a big pothole. Could the derailleur have gone into "protection mode" and by plugging in the power cable I "reset" it?
Now everything is working fine, I just wanted to understand what could have happened.


Their response was as follows:

1. Based on your text description, we cannot determine the cause of the malfunction. Please provide a video demonstrating the problem.

2. Please provide proof of purchase, a screenshot of your buyer information from the shopping platform, and your shipping address.

3. Please follow the steps outlined in to troubleshoot the problem and record a video of the process to help us analyze the cause.

My reply:

Hi,

1) I can't make a video now because now work correctly.

2)  i attach image of aliexpress order

3) None of the scenarios in the video happened.
The rear derailleur didn't give off any lights. Not even when I pressed the button for 30 seconds.
The front derailleur didn't respond to the left shift command.
The groupset wasn't reachable from the app.
I connected the USB-C charger to the front derailleur for 10 seconds and then disconnected the charger. As soon as I disconnected the charger, everything started working again, and I rode another 50km home. The battery was still at 65%. I didn't touch anything else, and everything worked fine again.
That evening at home, I recharged the battery, and it charged correctly to 100%.

My intention is to understand what really happened, why, and whether it could happen again, and under what circumstances.
Notwithstanding the fact that I now always have both reverse charging cables from my smartphone and a mini power bank with me.


I also asked the seller AliExpress (318Bike store) the question. He responded immediately, telling me he would look into it and to let me know if the problem recurred.