Do most cars run at 14.4v or less??

[ttran 10+ year member]

I have a honda s2000. Would a better battery like a red or yellow top help?

 

[Lakota 5,000+ posts]

Why is it going to steadily drop over time?

If you don't believe me, test it for yourself. Your car will start at a higher voltage once it hasfirst started. After a period of time it will drop a few tenths or more. Dash meter ftw.