[NUBEM3]

Hi,
Tried to search the forum for my question and couldn't get any thing. Must not have put it in right. So, please excuse if this has been beaten to death before.
I recently purchased, privately, a 2000 M3 Roadster and am completely new to BMW vehicles.
Within a month of purchase the battery went dead, but I think it had been in for 4 years. During this time the ammeter indicated a 14 volt charge all the time. I was under the impression that it was supposed to charge then move back to around the 12 volt area. I thought since the battery was so old it might be trying to charge it "harder". I put the new battery in and thought the ammeter would work the way I thought, but it is still indicating a 14 volt input and not coming down.
Is the indicated high charge rate normal, is there somthing wrong with the charging system, is the ammeter bad??
I have also run into some comments that these M3's "eat batteries" and that a charger should be kept on them if not driven for awhile. Comment??
Thanks for any info.
Ed

[Oldman MZ3]

Volt meter should read between 13.7 and 14.2 with a good battery, all the time.