[Cuog]

The KOP batteries are 17.2AH batteries. Your adapter can convert up to 85W so we'll use that as the max operating condition since such things are usually rated by the amount they draw from the source, and not the output(so that they can use higher more impressive sounding numbers).

85W drawn on 12V taken from P=IV(Power = Volts times Current) 85=12(I)

Current drawn will be about 7 amps. Therefore at full draw you can run for ~2.5 hours. Depending on how much current draw your devices take you can run a lot longer since even a laptop charger doesn't draw 85W(typically).

If you have a phone charger that only draws 10W then you can last for about 20 hours.

I wouldn't worry about discharge/charge cycles, my team has abused batteries we've owned since 2001 and they're still serviceable.