Thanks Cuppa. I did take a look at the cpap running specs & it listed the m/c in the 25Ah range, hence the 50Ah battery. The Nocco just illuminates an LED at 100% when it thinks it's completed it's work, so I just go by that.

Thinking about it, you may be right, maybe the cpap m/c is pulling more power than they state.

Might talk to local sparky and see if he has anything to measure power while the device is running.