Boxster voltage reading 17.5 - is this a bad voltage regulator?

[SC914]

taking the voltage at the battery , i am reading almost 18v. from the tech articles it seems this may be an indication of a bad VR.
-also there is a slight flicker i would call it at the dome lights too, - you really have to watch close to see this, but also the idle seems to vary along with this, and i dont think it is due to vac leak which would cause surging, the variation here is minimal , but not a perfect purr.
-
i did recently disconnect the battery to clear a check engine light and o2 sensor code - and replaced to o/a separator, and cleaned the MAF at the same time.
- currently there are no codes or check engine lights showing. -

- even when the car is off the battery reads @16v so is this normal?
- no corrosion at the terminals, and i have double checked the connections and grounds.

please advise, where to check , where to start.

PW

[Travis84]

Needs a new alternator. The voltage regulator is built in. Your battery voltage is high because the alternator is charging to high of voltage. I bet if you check after its been off for a while, battery voltage will slowly drop back down to that 12.6 range where it should be with the engine off. What year and model do you have?

[paulv]

No, it's not normal. With the ignition off, it should be approx 12.6v and at idle, approx 13.5 to 14.5v (close to 14.5 at higher rpms).

With the key off, turn the headlights on and let them stay on for a couple of minutes to remove the surface charge on the battery, shut off the lights and then take another reading. If the headlights need the key to be on to work, then turn the key on -- shut the key off when shutting the lights off.

17.5v is high with the engine running so this points to the VR being faulty. Most VRs are integrated in the alternator -- not sure about yours.

Regards,
paul...

[SC914]

forgot to metion that- i have a 2000 S with 71k miles,- i have had it for 6 months, put about 6k miles on it since purchase.

Phil