Theoretical lifespan of Spark Li-Hv
battery is somewhere between 150-200 full charge cycles. It's you, as an user, who can affect the real
battery health by taking proper care of it. I can recommend
msingers manual linked by himself above. Just be aware that the theoretical lifespan of 200 cycles doesn't mean that the
battery will hold as much as new one after 100 cycles. It's a fact that the
battery is losing some of its capacity every single time you charge it.
For example the oldest two of my four
batteries (those came with my Spark when I bought it) are at around 70-75 charge cycles now and they are showing total available capacity of around 1270 miliamps when fully charged. The newest
battery I have is now at 8 cycles showing around 1430 miliamps. The real difference in flight time is around 2 minutes (from the oldest
batteries I can get around 11 minutes before reaching 30% and on the newest
battery I can easily get 13 mins).
When the
battery gets older, it's good to observe the cells voltage balance too (three bars on the top with voltage readings underneath them) before and even mid-flight. It means that the difference between 3 cells shouldn't be bigger than 0,05 Volts (like 4.10V - 4.11V - 4.03V). If the voltage on one or more cells drops suddenly, the remaining
battery percentage will drop too (you might read some complaints about
battery charge drop from like 50% to 10% in a single second) forcing the aircraft to do emergency landing or worse.
I don't want to scare anybody but I believe it's good to know this.