I think the problem,with the cheaper ones ,is they are recycled batteries,
they don't all carry the same voltage or
Amperes ,a sure fire way to wreck torches,start fires and wreck any good batteries you may have,they also don't last as long as they are usually already part through their life in a laptop or power tool etc etc .
Buy cheap buy twice (usually)
there's plenty on the net about them ,I think a few links have been put on this thread early on.