Originally Posted by base2

Add to this list the batteries that are "keyed" to a particular motor controller/electronics package. You would think it would be a simple matter to carry a second battery & swap the out when one runs flat for really long rides, or simply as a replacement when the OEM one eventually dies. Nope.

The reason is obviously to prevent theft as no one is going to steal a $5k e-bike sans battery if only the original battery can make it work. And no body is going to steal the battery from some unlucky bike for their own e-bike if, likewise it can only work in the machine it is originally paired to.

In my mind, I am remembering a Giant, or maybe it was a Specialized...either way, it would be worth asking the bike shop you are buying the bike from & accordingly decide if batteries being "keyed" to a particular bike is a big or a feature.