Rapid Voltage Fluctuation?!

[bmrfreq]

I have an analog voltage gauge in my 97 328iS, and the voltage indicator needle fluctuates very rapidly between 13 and 14 volts. I assumed it was the alternator (internal voltage regulator going bad), but I just installed my third alternator thinking this was the issue, but nothing has changed and the issue remains.

If I check the voltage with a DMM at the battery, the voltage fluctuates there as well.

So, what could be the cause of the rapidly fluctuating voltage gauge needle?? (I have a video of the gauge needle, but saw no way of posting it here.)

If anyone has experienced this type of issue before, or if you have an idea as to what would be causing this issue, PLEASE let me know. At this point I am about 100% sure the cause is NOT my alternator.

Thanks in advance to all that reply.

-bmwfreq

[MarcoZandrini]

You need to have made 10 or 15 posts before you can add a picture. Most folks use a 3rd party website to post pix, and YouTube to post vids.

Varying voltage from 3 different alternators tells me that you’d better check the engine grounding strap. That strap is typically located at the bottom front of the engine on the exhaust side. The other end is bolted to the chassis. The connection need to clean and tight.

Question: are you sure the 3 alternators are in good condition. I know it’s a long shot that all 3 alternators have the same issue but I have to ask!