Battery Issues(subaru liberty 93 model)

[amraks]

Ok last night I went to Mc Donald's and went thu the drive thru.

I had my lights on and heaters going flat out, because its cold here.
sitting there for about 8 mins waiting for the people ahead to get their meals.
I noticed a sorter power surge like the heaters weren't going fast as they were before after awhile of waiting.
Then I drove out of the Mc Donald's to bp, filled up, Car would not start had to get someone to help roll start it.
got home 7km later pulled up turned car off and started it again and it turned on perfect.

Why does it not charge while idling for a long period of time.

I assuming this is a alternator problem. but I want some more idea's

[tassuperkart]

Id suggest you have a faulty phase in your alternator.
Tyhe windings will be fine, it will be in the rectifier. One of the diodes has died.
Run the car with lights on high beam and battery voltage should remain around 13v. Anything less than 12.5 and you have drama (which you do!)

The alternator will still work but heavy loads at low engine speeds beats its ability to hold output voltage so the extra juice needed to run your electrical gear comes from the battery instead unless you rev it up.

Id be either just changing it if you have a spare laying around of get an auto spark to test it.

L8tr
E

[Android 360]

could also be time to replace the brushes....
either way, just take it to an auto sparky and get it reco'd
it'll be as good as new!