Voltmeter acting weird

[bw4sale]

I noticed the charging system light in my '98 come on the other night on my way home. The voltmeter read at about 10 or 11 volts. I thought, "Uh oh". Alternator must be going out. But then about a mile down the road it jumped back up around 14 or 15. A few miles later back to 10 and then back to 14 in a few more minutes. Doesn't seem to make a diff on engine speed. Belt is tight. Is my alternator going out and is this normal behavior for when it does? Thanks.

[69c10stepside]

Check to see if your charging wire bolt is loose, I have seen that more then once on my own rigs, which of course, was my fault too.

[stovboltguy]

is it diesel or dual battery? my 96 diesel has done that when the positive terminal on the right batt came loose, alt still charged the right batt but left wasn't. gauges run on left showed low volt until i changed terminals.

[danomano]

Bad battery connection at the post. Change those first