electrical problems

[91 expo]

I’m having a problem with my electrical. My battery gage "dances" when I’m idling. And at night I can see that I’m loosing power because every time I come to a stop my lights all dim and flicker. Now I had this problem before with my 93 ranger, but I found that it was just the battery connections weren't tight. And so there wasn’t a solid current being pushed through. But I know it's not the connection this time. And I’m wondering what it could be? A friend told me that it could me my alternator but who know. So if anyone thinks they can help I’d really appreciate it.

 

[MazdaGreg]

When this happens, do you have any accessories on?

I know on my Navajo, when i've got Defrost (AC Clutch is on), Rear Window Defrost, and headlights on (Every Morning this time of year) every time i come to idle, the voltmeter drops off of around 14 and heads towards 11 or so. There are no numbers, but i know what it's doing in real life. you fall off of the alternator's ability to keep up when it drops speed at idle.

So i guess my question is, describe dancing more... what is the truck doing. what are you doing?