On Wednesday, July 10, 2019 at 2:23:24 PM UTC-7, wrote:

My Shimano Di2 7970 battery last 2-3 YEARS between recharges. YEARS!!!!!

I suppose if you never ride, a battery can last a long time. According to https://tempocyclist.com/2016/02/02/di2-battery-life/ "From a 100% charged starting point, the indicator light on my system changed from solid green to blinking green at 750 miles (1200km). I do change gear quite often, but not so much on the front which requires more battery power. After 1030 miles (1650km) the indicator light changed to solid red."

While I presently have about 2000 miles I would normally have 4,000 after the 7 months and since I'm riding fast I'm probably shifting more than this reporter.

But I actually only have about three months of riding about 3 to 4 times a week. That looks like I would have had to completely recharge the battery twice.

Exactly how is it that you're getting 2-3 years?