Normally, I have the planes on a wall charger which is on a timer for 2 hours per day so the plane is ready anytime. Last weekend, one plane was off the plug for 2 days so at the field I checked and was surprised to see voltage at 4.8 so I topped it up and it took 200 mAh. I was surprised I would loss that much in 2 days.
So I did a test the past few days; charged 2 planes up (both have the same battery ; 4.8V, 1100 mAh). Both were at 5.1V when done. I unplugged and watched the voltage. Both dropped the same but were at 4.7 after 2.5 days. My rule of thumb is 1% loss per day for NiCd so this surprises me. I do not think I have a bad cell as both batteries are doing the same thing and at the field, I can fly 3-4 flights and still be above 4.8V.

Is this normal? Surprising? The only thing I can think of is to cycle them as I am likely only using <200mAh each time out and then top them back up...

Thoughts appreciated