Can’t always charge them at work, and I would forget them I think 
But the broken rear light, it was only the clip, is reused. I’ve taken apart the rear reflector (removed the reflecting red part), and glued the back of the light on it with Tec7. I don’t think it’ll fall of, ever. 
The rear light itself also doubles as a reflector.
I also have one of those cheaper decathlon-thingies hanging on my backpack, just in case.
As for the front lights, did an order on aliexpress just the other day. Let’s wait and see what China can offer us for about €3
The Sigma light wasn’t the smartest choice, and I don’t think it can handle being taken off and on the mount all the time…