I measured my "cigar socket / outlet" with a multimeter. Instead of 12v it had 19v. Is this normal? Is it my voltage regulator, alternator, battery that has problems?

Car: Peugeot 307, 2.0 XSI 2003 The 12v "cigar socket / outlet" is off when my key is turned off, and on when I turn it on.

Additional information: Battery is almost 1 month old. Mechanic replaced it.

Voltage car off with key not inserted
Battery -  12v socket
16,67v     0v

Voltage car off with key turned 2/3 steps
Battery -      12v socket
not tested     18,2v

Voltage car on
Battery -  12v socket
20v        20v

Voltage car, airco, headlights on
Battery  - 12v socket
20v        20v
  • 1
    Did you check the voltage output at the alternator as well? – Pᴀᴜʟsᴛᴇʀ2 Mar 28 '15 at 11:31
  • I guess I should have first asked if the car was running or not (with key not just in the acc position) when tested? – Pᴀᴜʟsᴛᴇʀ2 Mar 28 '15 at 13:04
  • I've added additional information in my question above. Thanks – MOTIVECODEX Mar 28 '15 at 14:36
  • 2
    Are you sure your voltmeter is working properly? – Paul Mar 29 '15 at 18:58
  • @Paul I am going to the mechanic tomorrow. I think and hope my multimeter is busted. Tested it with my power supply and it gave +2 volts readings. Still the car battery would be too high, even with +2 volts wrongly added volts.. – MOTIVECODEX Mar 29 '15 at 20:29

Went to the mechanic, and the voltage looked good at 14,4v +- when everything (car, airco, lights, radio) were on. Looks like my multimeter is busted. Need to buy a new 9v battery for my multimeter to test if that fixes the offset, or I'll try to calibrate my multimeter.

Anyways, always test with another multimeter if in doubt.

  • 1
    You can also test on a known source, which is a procedural requirement for professional electricians. – Paul Mar 31 '15 at 21:45
  • Yes, I did that and it gave wrong values. Even with a new battery + some calibration it still has big differences. Time for some a new multimeter. – MOTIVECODEX Apr 1 '15 at 18:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.