[Biker1]

I have 3 batteries but I always carry just 1 spare. So I have 2 total with me.
I never needed the third as I am near a power supply by the time the second battery is depleted which is rare.
But that energizer unit is good to have around in case of a power outage, etc.
Certain states have powers outages constantly during certain times of the year but I guess you can always charge your device using a car battery.