Battery an both battery cables are new,alternator was replaced recently, connections have been cleaned. Had it tested at shop alternator, battery load ck. Every thing passed. But I can drive the car around for 1/2 hour or so shut it off and the battery won't start the car. always carry jumper cables every were I go.:/ Any ideas I was thinking ignition switch maybe shortin out? Starter ,? Besides charging system check well running, also had the alternator bench tested off the car an passed also, .I am stumped. Any help appreciated.
My car has 150000 miles.
My car has a manual transmission.
Hello, You may have a failing voltage regulator that could be allowing the alternator to supply too much or too little amperage to the battery resulting in the battery never maintaining a consistent charge as it is designed to. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. You may also smell a bit of smoke due to things potentially getting too hot. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.
Have a car question? Get free advice from our top-rated mechanics.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing