[Chris is me]

Originally Posted by Munchskull

Electrically speaking the age alone of a battery is irrelevant to it performance. What you should really be checking for is internal resistance.

You're absolutely right, but I think the point of doing this is less that something magic happens after two years to make batteries terrible, and more that batteries don't' cost that much to replace and it's easier to cycle out batteries early than to discover too late that you have a sub optimal battery.

A lightly used, well cared for battery can last longer than just two years, while a heavily used battery that is poorly mantained may not even last that long. However you are right that the battery will increase in resistance with aged, but the lagest factor in a batteries life expectancy is not the age but the usage and care.

I mean, the way batteries are used in FRC is inherently suboptimal. We use the batteries hard for two minutes, then throw them on a charger well before we've mostly discharged them, and usually to charge at a higher current than they should. We're already abusing these batteries.