Contrary to other bad experiences, my ER9 groupset has been working really well. It took a few rides to iron out the kinks, but right now it's running near perfect. I'd almost be tempted to buy another ER9 set! Though I bought it with really low expectations, with the belief it will fail on me at any given moment. If you want race ready equipment with money spent on R&D, extensive customer support and quality assurance, no one should be buying any components from AliExpress!

The repeated issues with this groupset are almost pushing me towards disregarding the groupset entirely and move to shimano. As a final and desperate move, I will try it with higher quality batteries. Thanks for the input all.

If you want to nerd out, you can buy a lithium battery tester. I have an EUC i use to ride around town, and i've had extensive problems with its battery, so i've become pretty knowledgeable about lithium. Testing cells is often step 1.
In Europe there's a reputable shop that sells 14500 batteries that's been recommended here several times. I bought mine locally and they're shit, in the sense they have low capacity, but they do work.

To be fair to LTWOO, lithium on planes is such a ridiculous ordeal that it makes sense that as a direct to consumer brand, they have the option to sell groups w/o batteries. It's also in line in spirit with right to repair and all that. Regulations around carrying even the smallest of batteries is stupidly strict, not unlike limiting ebikes at 25kmh. Laws that defy all common sense.

These look OK at first sight: https://www.aliexpress.com/item/1005005871463985.html
Reviews are good and people seem to have measured them. Capacity even looks higher than stated.

Not sure if this prognosis is exhaustive, but there is probably a problem with 1 of the 14500 batteries I had on my bike. Just compared two "new" 14500 batteries which were giving ±4 volts. The ones installed were giving ±3v (which apparently is the cutoff?) and ±3.5v.

4,2V = fully charged. 3V is definately empty and very low

The repeated issues with this groupset are almost pushing me towards disregarding the groupset entirely and move to shimano. As a final and desperate move, I will try it with higher quality batteries. Thanks for the input all.

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