> Weird car starting problem any advice?

Weird car starting problem any advice?

Posted at: 2015-01-07 
If you are having the battery going dead in that short of time then I suspect the alternator even though it still tests as good. There are three circuits in the alternator that make up the charging circuit. They produce alternating current (that is why it is called a alternator) you can not charge a battery with alternating current so there are diodes built in to change it to direct current. I think one of these diodes has failed and is letting the current back into the coils. If I'm right the alternator will get hot to touch after the engine is turned off.

The terms you use are like guessing. Seem and sounds like. Get a volt meter and google how to use it here. Car running ...put meter on DC and check across the battery. Needs to be at least 13.5 volts at all engine speeds and with lights and AC blower on. Switch the meter to AC and it should be close to zero. This is knowledge you can draw on the rest of your life. Auto zone is for PARTS.

The worst thing for an alternator is a failing battery. You jump a dead battery over and over you are taxing a weak alternator into oblivion trying to charge that dead thing.

Have your battery LOAD tested by competent tech., parts countermen are NOT mechanics, most are not familiar w/ proper test procedures.

you have a bad battery. it sound's like it has a dead cell. so it may check fine but really isn't.

Car set for awhile not being driven started every once in awhile then one morning completely dead. Got a jump started jus fine turned car off tried to start again back dead, the weird part is I took battery to autozone charged it and it tested good, put battery back in started no problem after maybe 30mins of sitting back dead I don't get it if it jus tested good where is my juice going? I even disconnected negative cable on battery while car was charging to see if it would shut down do to bad alternator found out that I could have fried my computer doing so but nevertheless it stayed on so any clue on what this can be? Alt or bat even tho they both seem to be good