How should you carry a spare battery?

[readingaloud]

I just got an extra Panasonic battery for my new Flyer, and was a bit surprised that it didn't come with some kind of case, or at least a cap to cover the terminals.

I'm thinking that I could just wrap it in a water-tight nylon bag and strap it to my rack. Is there a better way? How do other folks carry an extra battery (when you do carry one)?

 

[flecc]

I use one pannier, even with a 5.5 kilo 36 volt 10 Ah NiMh battery. There's no imbalance once riding.
.

 

[stokepa31_mk2]

I too use a pannier and do not notice the weight.