Battery? Or is it?

Hi. went to start my bike today and whilst everything came on nothing happened when I hit the button!

Tried a few more times and occasionally there was a click and the fuel pump reset itself but apart from
that nothing. A couple of times there was even a half turn of the motor.

The reason why I'm not sure it's the battery is that the headlights remain on with no dimming when this happens and also I have put a booster pack on (which can start my Range Rover) and this has no effect!

Any thoughts?

Here is the electrical starting circuit simplified for the Roadster. Before you start, make sure you have tight connections at the battery, starter and ground locations. Battery should be charged and reading close to 13 volts. Check the battery voltage when you push the start button (should drop a bit). It sounds like this is happening due to an incomplete, open or corroded starter circuit.

You state that the lights don't go out when you push the start button. That is a big hint. The relay doesn't appear to be switching power from the lights to the starter solenoid when start button is depressed. The circuit that powers the starter relay needs to be checked (ign switch, fuse 5, kill switch, alarm bypass jumper plug, start button, starter relay and ground ). All of this can be checked by switching out the 5 pin starter relay with another to see if that doesn't fix things. You should hear the relay click. Since the lights aren't going out, I would assume the feed to the relay from the start button is corroded/open. I've seen the start button contacts corrode in the past enough to cause this problem. Also, loose fuses in the fuse holder or corroded alarm bypass jumper plug. Just make sure you start with a good battery. Saves you chasing after ghosts.

Check and clean battery connections.

Have you waited a little while between connecting to the (running) car battery (or booster pack) and trying to start? When the battery is really bad, it may take some minutes, up to 10-15, before the starter will work. Sounds like a dead battery anyway.

Hi all and thanks for the replies.

Sorry for the delay but my PC decided to throw a strop and stop working!

I should have explained the lights not dimming better, I meant that usually when a battery is dying the headlights dim as they draw power and they weren't doing that.

Thanks for all that input Gregger, it's really useful for future reference.

So as it turns out...…...Battery! Even though it was saying charged the little sod was lying!

Now I'm £87 poorer with a nice shiny, taxed, insured and MoT'd piece of sculpture as even though I ride alone, wear a full face helmet, put fuel in at a self service pump and don't stop whilst out it has been decided that I could infect people so have to stay in!!

Love it