OK, stupidly left my car for a few weeks and the battery is totally dead. Put it on charge, and initially it took no current. Left it on for a half hour or so and it started taking 2a. After a few hours it's now taking 6a. Anyone know if this is normal? The battery is fairly new, it's got a 3 year warranty, so if there's any easy way of diagnosing a stuffed battery I'd like to know, so I can have a go at getting a replacement!