I have been using my rMB 90% of the time on battery. Roughly 20 cycles a month. (458 cycles in 23 months). Battery health has been fluctuating quite a bit all the time. (sometimes more than 5% on one day). But it has last me through the day most of the times. So I am pleased with that. Lately I have been able to use the rMB mostly on mains 90% of the time. Only 2 cycles on the battery this month. The battery health is much more stable (fluctuating max 1-2% only on a daily basis). I wondered if those of you who have been using their machines mostly on mains have (much) better battery health after 2 years than those who have been using the battery most of the time. After two years of use my battery health lies around 80%. How about those who have used it on mains? Obviously you will have less cycles but do you get more hours out of your battery when you use it. Altogether I might have lost 2 hours of use on a full charge since day one (but this is a very rough estimate). I am planning to get an external battery pack for those occasions when I am not able to use it on mains over considerable time and thus save what I have left on the rMB battery as much as possible so that I might avoid a new rMB battery. I live very remote and there is no Applestore/service nearby. Sending it in would at least take 3 weeks altogether. Beside that I would save quite some money (250€ vs 60€ for a battery pack with usb-c).