How hard is it to get a replacement battery for a Lexus RX400h off the shelf. I don't really want to go to Lexus and get fleeced. I've tried a couple of high street multis. They don't seem to carry a large stock of batteries. This morning I was presented with 4 batteries at a battery/exhaust fitting centre, none of which would fit the car. Can anyone supply a battery name or serial number which will be guaranteed to fit. Any help gratefully appreciated.