LTWOO ER9 & ERX - Electronic groepsets

[Sebastian]

The battery status in the app was pretty accurate for me at least after one or two charges. The low battery warning on the head unit however is a well documented bug that hasn’t been fixed yet. It happened on my Wahoo, too. The only way to stop it is to disconnect the groupset  from the head unit.

[amacal1]

Guys, running ERX for 4 month now, so far working but with annoying message from Garmin everytime that the shifter battery is low.
I run into issues with wet weather and cold temperatures. Battery died quickly, although the App/Derailleur shows that the battery is fully charged.

It seems that using the App leads to incorrect charging, so do not try to read the battery status with the App. Just plug the cable into the RD and let it charge.

Did the battery die to the point that it couldn't shift? Or, were you just using the head unit's warning as the indicator that it died?

All of the Ltwoo groupsets seem to report bad battery data to the head units, but for me the app has never indicated anything other than reality. What the app says is true, what the head unit says is likely not.

[crazycat]

Sorry for the lack of clarity!

@jonathanf2: I’m aware that the warning from the head unit is a bug; I just wanted to mention it.
@amalcal1: My battery dies suddenly, and I couldn’t shift.

Let me explain the issue in more detail:

It first started when I wanted to ride home, but the battery was dead. This was surprising because just a few hours earlier, I finished a ride without any problems.

I charged the battery, and the solid green lights appeared very quickly. That’s when I started checking with the app.
The app showed the battery at 100%, but when I disconnected and reconnected the app (without the charging cable), it dropped to about 8%.
When I reattached the cable, the solid green light came back quickly, and the app again showed 100%.

It got so bad that I could only shift gears once or twice before it stopped working, even though the charging cable had shown a solid green light.
So, I left the app closed, attached the cable after the rear derailleur went idle, and it started blinking green. However, whenever I opened the app, the green light turned solid again.

After charging (attach the charging cable when the derailleur is in idle mode) without opening the app, the green light stayed blinking and only turned solid after 2-3 hours.

This is why I suspect there might also be an issue with the app.

[amacal1]

Sorry for the lack of clarity!

@jonathanf2: I’m aware that the warning from the head unit is a bug; I just wanted to mention it.
@amalcal1: My battery dies suddenly, and I couldn’t shift.

Let me explain the issue in more detail:

It first started when I wanted to ride home, but the battery was dead. This was surprising because just a few hours earlier, I finished a ride without any problems.

I charged the battery, and the solid green lights appeared very quickly. That’s when I started checking with the app.
The app showed the battery at 100%, but when I disconnected and reconnected the app (without the charging cable), it dropped to about 8%.
When I reattached the cable, the solid green light came back quickly, and the app again showed 100%.

It got so bad that I could only shift gears once or twice before it stopped working, even though the charging cable had shown a solid green light.
So, I left the app closed, attached the cable after the rear derailleur went idle, and it started blinking green. However, whenever I opened the app, the green light turned solid again.

After charging (attach the charging cable when the derailleur is in idle mode) without opening the app, the green light stayed blinking and only turned solid after 2-3 hours.

This is why I suspect there might also be an issue with the app.

Any chance you have a bad battery / cell? Any way you could pull them out and check them with a battery tester or multimeter?

[Serge_K]

FWIW, having broken too many ER9 to keep count, i can recommend https://eu.nkon.nl/rechargeable/li-ion/14500-16340/size/14500.html as a source for batteries. I bought several pairs of "EagleTac 14500 750mAh - 2A", and they are so much better than the batteries i had originally. I have never used the original ltwoo batteries.
These batteries hold their charge soooooo much longer, it's day and night. they were ~5 eur each, and shipping was ~10 eur, so ideally, you have friends who need batteries too to avoid paying 20 eur for 2 small batteries.
Now, these batteries dont prevent RDs from self destructing for no reason (aka "the ltwoo guarantee"), but your group is much less likely to die mid ride because the batteries dont hold a charge well, and shifting is more reliable, crisper, because the battery isn't $hit.

[Sebastian]

From my experience there’s basically three sources of battery problems:

1. The batteries themselves obviously which can only really be verified with a testing unit. I bought a testing/charging device and all my batteries turned out to be well within spec.
2. Connectivity issues between the charging port and charging cable. Clean that port on the RD well with alcohol. Any dirt and contact issues can lead to weird behaviour upon charging. I even had the battery discharge instead of charge when the connection was less than perfect.
3. If none of that is an issue and all the cables are perfectly attached, no moisture or water ingress, then the RD is probably to blame. Because it’s the brain of the whole system and manages charging.

Ok. That was more than three problems. But you get the idea.

[crazycat]

Its either the battery or the RD. I didn't do a capacity test, but when the app tells that the battery is full, I measured the voltage and it was 4.1 for each cell.
Again, brought back bike after 5km only today, put cable on and removed it after green light came up continuously. Then open the app, and status was 86%.
If I attach the cable again (RD didn't go into idle), green light appears continuously (battery full).
But after I wait until RD goes into idle and then attach the cable, it is blinking and charging further for a while.

Anyway, I don't bother to debug anymore, will replace it with Shimano soon.