I bought a Renault Scenic Auto 2004 to get me mobile until my ankle replacement gets better to drive a manual. However it wont change up into top, doing 3500 rpm at 60 mph for some miles then eventually decides to change. I am being told it is the battery that needs to be in very good order to control the gear change. Does that sound logical or does it sound like I am being told porkies?

Might be worth checking the alternator output but it could also be a faulty box? I haven't had a lot of luck with Renault auto boxes , could be " The diamond of doom" ?