Originally Posted by
Flamme Rouge
I've been using an Anker PowerCore external battery with my 820 ($15 on Amazon). It fits in small bag that sits on my top tube. I start with the charger connected as noted above. Haven't figured out what to do when raining, however.
I unplug mine in the rain. OTOH I don't intentionally ride long distances in the rain anymore. My 800 will run ~10 hours on its internal which stays full while it's connected to the external battery. If there's going to be more continuous rain than that, I'm either staying home or getting off the course somehow. Of course I'll always have my wired odometer and a printed cue sheet in a waterproof holder, so theoretically I could fall back on that. I was never fond of trying to read a cue sheet in the dark and rain even before my eyes got bad.