Smoke alarm

The smoke alarm started to go off in the middle of the night- always the best time to inform you that it needs a new battery or needs to be replaced. 
It was a sealed unit with batteries that are not replacable. I was curious to see what was inside so I opened it up. 
Seems like a total waste of resources that this is now heading for the bin- well the recycling centre. 
Thankfully the high pitched chirp that went off every 45 seconds has stopped.