So I drove my R56 to work today then 20 minutes later I was going to move it then it wont start, Dash lights are still intact but won't start so I took one of those portable jumpers at work then it starts then few hours later I was going to lunch then it won't start again so I did the same thing so it started, Got back to work I left the engine running for at least 30minutes and hope everything is okay then I turned it off. I get into my car and it won't start again.

What could be the problem? At idle the accessport reads 14volts

 

I would say your alternator is working fine if it reads 14 volts. Your battery most likely has a bad cell that won't let it hold a charge.

 

Yup, 14V during idle is a sign of a good alternator. Your battery is focked.

 

Just want to throw out that an alternator can read proper voltage and still be bad. Bad diode not enough amps so on. Most likely you need a new battery though.

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