new volt meter

Actually, you probably should. Did you bypass the ammeter AND ALSO add a wire out in the engine bay between the alternator and the battery?

Look at the simplified diagrams in the MAD article:

(There IS two pages to that article!!)

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

If you bypass the ammeter, AND add a wire under the hood as mentioned, there now is a situation whereby there IS NO fuse protection at all for the original red or black ammeter circuit, because the added bypass wire now feeds power in parallel, from the battery (relay stud) to the alternator stud, up the original black ammeter wire, to the new junction.