Battery not holding charge

[Swoggy Loiner]

I seem to have aquired a problem with with the battery/ electrics on my 92 exup. The bike wouldn't start last week , after a few days sat in the garage. I charged the battery, fired straight up, then went off to work. Fired up (a little sluggishly) for the journey home, no probs I thought. Whilst sat at the lights, the bleeding thing cut out, and wouldn't start again!! Luckily the road works lads gave me a bump and I made it home. I've since replaced the battery, but it's still going flat after a day or so. Starting to seriously do my crust in now. Anyone any ideas? Thanks

[RAG TOP]

check the alternator is charging,if you don't have a multi meter turn the lights on with the motor running directed at a wall and see if they get brighter when the revs go up.