There seems to be a lot of hassle and angst involved with some of these cheap lighting solutions. I can understand people wanting to get good light for not much money but for me I'd rather pay a bit more for a product that is just going to work. No hassles with dodgy batteries, iffy connectors and shonky mounts.
Something I have every sympathy with, but there are two issues:
1. Even after buying an aftermarket 'reliable' battery and charger, they are still a lot cheaper than other offerings.
2. The stock stuff actually is fine for many people. Maybe even a majority, I don't have any stats. from my experience I have 3 Chinese batteries , some over a couple of years old that still work well and charge reliably. I had a scary issue with a charger (which I think was my cheapest acquisition .. I buy many of these out of curiosity) suffering a a smoky death whilst I was in the garage, now I charge them in a metal box with a timer, which probably isn't bad practice anyway.
If you buy with your eyes open, which thread like this contribute too, you can be riding when maybe you couldn't before. Which is nice.