4.20...
The wind is down and I'm charging batteries to catch a few model aircraft flights this morning. The batteries I use are lithium polymer or Li-Po for short. They develop lots of power for a short time, so I have several when I go flying.It's important to monitor the flight time because draining a battery below 3.8 volts will shorten its life. Batteries are pretty expensive, around 25 to $30 a piece for the style I use.
Depending on batteries deserves a Blog of its own!