previa alternator

As a general rule, a bad battery will recharge itself.

Intermittent loss of power is usually due to a poor connection somewhere like the battery terminals or a bad alternator. Since the shop tested the alternator and pronounced it as bad, then the alternator is suspect.

I agree with Ray. I would clean the connections going to the battery. If the battery light comes on again, I'd get a new alternator. The alternator is 17 years old or so. Perhaps it is getting old.

Jeff

I'm not trying to be a wise-ass here but is there some reason why you don't believe the shop? Alternators are a lot harder to change then batteries. If he was just trying to get in your pocket, he'd sell you a new battery.

Jack

91 Previa, undoubtedly over 100,000 miles - It's the alternator, most likely worn rotor brushes that when they hit a critical wear point will go intermittent for a while (sometimes it charges, sometimes it doesn't) before they finally wear down too short to work even when cold.

You can just get a set of brushes for ~$5 and change them, but it's better to take the alternator out and have it rebuilt. They install new brushes and check the diode stack and the voltage regulator for proper function. They also check over all the mechanical wear points

- pulley sheave, bearings, slip rings - and replace as needed.

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I didnt say I dont believe the shop, I was asking whether there are other possible explanations for those symptoms. I should have been more specific: he put his meter on the battery and announced it was only charging 13 amps (or something like that), and THEN said it was the alternator.

If the shop full fielded the alternator and it only produced 13 amps, then the alternator is bad. Fortunately, changing the alternator in the Previa is not a very difficult task.