[selimthegrim]

The horn depending on the battery is frightening

[quesera]

I'm having trouble envisioning an alternative power source for the horn.

Compressed air maybe, recharged by electric motor when available. Sounds like a reliability problem to me though.

[zerocount]

Why? I've only used my horn for telling people to get off their phone and go because the light turned green. I can't remember it ever being a necessity.