The tyranny of battery powered devices for cycling

Recently I saw a forum post in response to someone who was installing a hardwired light on their bike.  The commenter said something to the effect of "It seems so much simpler to just use a battery powered light.  You put it at the store, strap it on, and you're good to go."  Clearly they haven't experienced recharging fatigue.  When I go riding, I have the following battery powered devices:

1. The e-bike itself

2. Lights (front and rear)

3. Varia Radar (in lieu of the rear light)

3. My cycling computer (Garmin Edge or Hammerhead Karoo)

4. A navigation unit (Leomo Type S, Smart phone, or bike nav unit)

5. Action Camera (Sony or Garmin Virb)

6. Headphones (Aftershoks)

7. Lighted helmet (Sena)

8. Speed and cadence sensors (if the bike doesn't have those built in)

9. Heart rate monitor (Garmin ANT+)

10. Juiced bikes Alarm/Horn

11. AlterLock tracking device/alarm

etc.

I don't need all of these for all my rides, for example, I don't need lights if I am leaving during the daytime and know I will be coming back in the daytime.  I don't need the navigation unit if I am going a short distance and I know where I am going, etc.

I don't *need* the radar, and only worry about it if I am going a long distance on the road.  Likewise, I don't *need* the horn, except when I do - also when I am traveling on crowded roads.  

If I am going a long distance at night, I need most of these things.  

Now, the ANT* sensors basically run for a year off of a watch batter, so there isn't much to worry about there.  Likewise, the horn and AlterLock can be charged about once per month.  

The nav unit is critical if I don't know the route, and the light is critical at night.  Obviously I don't *need* the camera, but I like to document my rides.  

The camera and light use the most battery, followed by the navigation unit, bike computer, and maybe Varia Radar.  Numerous times I have planned to leave, only to check and find something was running low on batteries, and had to delay my trip.  

This can be solved to a certain extent simply by having multiple batteries for some devices.  I have an extra battery for my Knog PWR light, and for my cameras as well.  This way, I can have one always on the charger ready to go.  Still, the more devices I have to worry about, the higher the chance I will have something run down when I need it most.  

Since the light is one of the most power consuming devices is the light, it makes sense to have it hard-wired into your main battery if you have an eBike.  I think the horn also makes sense, since it's a safety device.  Usually the time when I find out that the battery is dead is exactly when I need it.  The dangerous car swerves in front of me, or the crazy cyclist ignores a red light and flies across the intersection right in front of me, I press the button, and... nothing.  

Some eBikes (like my Yamaha) do have USB out, but that can only power one device at a time, and usually only at a low current.  It might make sense to keep this connected to the nav unit.  

By hardwiring the front and read lights, and the horn, the main worry is then the nav unit and camera.  The camera is not critical and has interchangeable batteries, so we have whittled the problem down to the nav unit and maybe bike computer at this point.  If you keep those two plugged into the charger when not in use, then you're good to go.  In the case of the Leomo, there is an extended battery available for purchase to lessen anxiety even further.