New replacement battery quickly drops to 7% and stays there, why?

It may be a bad battery logic, but allow a few charging cycles to be on the safe side. Some batteries may just need a little use to get into full shape, other will just stay as they are or even get worse soon. You can have a look at Coconut battery to get info on its condition at a glance.

I have the same problem, at the 27% mark the battery drops to 7% holds then shuts down. The crazy thing is that i loose a few percent capacity each time such that my capacity shows 81% by the 17th charge cycle. Not normal! I contacted the distributor and they are awesome, they have been replacing my battery each time no hassle. I am on my 3rd batter in about a month and half. lets see how this one works out. Your situation is not unique and I’m afraid that the manufacturers are pumping out worthless batteries. find a good supplier and keep trying until someone figures something out.