Double Negative wrote:
One thing to keep in mind about battery "age" is that it's not necessarily how old the batteries are - but the cycles. That is, how many times they've been drained/charged.
This is very true & my experience with lithium polymer & lithium ion batteries used in radio control airplanes is that after more & more charging cycles, the percentage of charge after a full charges starts to steadily decrease below a full (100%) charge. This failure to take a full charge is another indicator of battery weakness & possible need of replacement. Our battery percentage indication above the check battery warning should also show any battery not taking a full charge after too many charge/discharge cycles.