I would say the day it only charges to 41v it has had it's time. My bottle battery only charges to about 41.2v these days so I only use it in parallel with 10 Ah of LiPo and since I started doing that it is pretty stable.So, a year on and the system works well. However the Ezee battery (that I suspect is pouch cells) now only charges up to 41.1v. Seems to hold the charge fine. So I'm wondering, at what stage do you call it a day with a battery? Couldn't say what it's range is now because I've been using it in parallel since the OP here. The max voltage difference is getting close to the 0.5v differential that I have in mind as a safe limit. What do you reckon?
The Insat battery (Boston power cells) always has charged to 41.5.