Luna 52V, 10 ah Battery

My Luna battery is nearing its fourth birthday (can't remember the exact date when purchased, but right when they started offering them) powering a BBS02 off road or a 1000w DD rear hub for errands. It's operated off road about twice a week and once or twice a month with the hub, so a total of 400+ charge cycles during this four year period. I charge it fully just before using, then let it remain at 20%+ after using. Tested it semi-quantitatively riding up a 7.9 mile 2190' ascent that required about an hour, the relatively easy pace that I'm accustomed to these days. The return trip was almost all downhill, so shut the system off. Check of the voltage after the ride suggested that about 40% of the battery capacity was used (battery at 52.6V), so 25 or so watt hours per mile going up, nothing on the return trip and about 13 watt hours per mile total. Looks like the old battery still has life. Best news is that it will still provide enough power for my "normal" 15 - 20 mile ride.