I've had my HVR-Z1U for only a few weeks. Around about the time of purchase, I read somewhere of the experience of another owner concerning battery life. He said he was happy getting 7 hrs out of an NP-F970 battery. The one that came with my camcorder is an after market version and when it charged up to 7 hrs use showing up on the charger, I was happy. After 2 more charges that dropped to 6 hrs 33mins, so I fugured it better to get another battery than get caught.
I bought 2 new aftermarket batteries of the 970 type. The website said some batteries were fully charged ex factory so I checked both of mine. They showed just over 50% charge and a usage of LCD screen 277 mins and viewfinder 299 mins..
One never really knows what are the real facts in advertising, but when I put one battery on the charger, it showed a battery life of 40hrs +. That was over half an hour ago and now shows 47hrs 41 mins.
I wonder what the real figures are..??? lol. Guess I'll have to wait and see.
The website is Australian.

My experience with aftermarket batteries and Sony camera's is that the read out for remaining battery life was never correct, they lasted a bit less then the original but if I wanted to know exactly how long I had left I needed to use an original one.

Can anyone tell me the best way of discharging a battery to recycle/recharge it, please? I am lothe to just run the camera as a way of discharging it

I think that's the best way. You don't have to run tape, just the cam.

Unless you have another device, like a deck or light, that uses the same batt.

OK Adam. Thanks for that. I don't have any other gear that uses that type of battery.