Mr L had 3 smoke alarms bleeping low battery warnings and the sound was getting very annoying. Perched precariously at the top of a step ladder and leaning a bit on the wall for reassurance, I managed to change the two on the highest ceilings. Annoyingly, the third was a bit broken and no matter how much I tried I couldn't get the case open. We agreed to leave it as is, and I suggested getting someone from the manufacturer or installer in to replace it. I moved their newly emptied dustbins in off the road to make up for it.