Like the title says...

battery light comes on from time to time...if I shut the engine off and start it back up, the light usually stays off.

...

father says I should get a new belt/have the belt tightened (the belt squeals from time to time)

what do the experts say?

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1982 240D.
My name is Michael, and I am an 18 year old binge-drinkin', cigar-smokin', novel-writin', all around unsavory and unnattractive guy. I tell long-winded stories, and I only shave once a week, although I've had to do it every day since I was 16.

That would be the easiest, cheapest and simplest solution, yes, check the belt tensions first...then you could be looking at a voltage regulator or alternator problem if that does not fix it.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz