I have had a secondhand rover 600 1998 for about three and a half years. I have not replaced the battery yet. During the last week my car alarm has sounded twice in one night and tonight it has gone off again. The other afternoon I checked the battery and I could see the green light showing (battery ok) Later that night I checked the battery again but I could not see the green light. I had someone put a tester on the battery and he said it seemed to be holding its charge. Will the alarm sound if the battery is defective or do you think the problem is the actual alarm.

Hope you can help
Cheers John