Battery Over Charging?

I have a 2005 heritage softail classic fuel injected. The battery keeps dieing, but I can get it started with a battery charge. It runs like new while it's running. I checked the battery with a volt meter. At idle it at about 14.3, but here's the problem when I rev the motor it jumps to about 17.5 - 18. I know this is not right and I'm thinking I have a regulator problem but I'm not sure. The stater seems to be working because I do get a charge to the battery but it's too much charge. I also thinking the reason the battery won't hold a charge is because it's been over charged while it was running. I'm really looking to see if my thoughts are correct or if I'm off base. Thanks.