Voltage Regulator in cold weather

I am re-posting this question as original post did not get any feedback.

On my MY02 WRX when starting in real cold weather (10 - 20 deg F) voltage gauge jumps to 16.7 V and holds at 16 V level even with headlights, defroster and fan on high for several minutes - until engine warms up. After that it gradually drops to "normal" : 13.8 V while driving and around 12 V while idling on a traffic light.

Did anybody had similar experience? I am not happy to see car electronics experiencing 16+ V even for couple minutes, but to demonstrate this to the dealer I would need a really cold weather and car spending night in dealership.

Reply to
David Spektor
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Reply to
Tony Hwang

I'm not a mechanic, but I'd guess your system is doing what it's supposed to be doing. Batteries tend to lose their charge easier in colder weather, and have to work harder to crank a cold engine. Sounds like the system is detecting your batt is further "down" and making up for it with the higher initial charging voltage, then backing down as the battery comes up.

Steve

Reply to
CompUser

That is typical, lead acid batteries require higher charging voltages when they are very cold vs. very hot. Auto electronics is built to run at nominally 14V but must withstand a fair range to either side of that plus possible transients (load dumps)

*significantly* higher that 14V (say even 50 V or more for 10-100 milliseconds). I would not worry, the car electronics should be designed to operate at these conditions indefinitely, though you (or the dealer) could double check the accuracy of the gauge w/ a good, *calibrated* digital voltmeter just after a cold start.

The drop to 12V at idle occurs because the alternator does not quite keep up w/ the load at idle speed, again not unusual.

Reply to
The Masked Marvel

Sounds normal. As others have said, your battery takes quite a hit when it's cold, so takes a bit more voltage to recharge cold than in warmer months. As to the actual voltage, is that measured with a meter or just off the gauge in the dash? I wouldn't trust the dash gauge for absolutes, just to let you know things are in a "normal" range. For example, when mine says 12 v, a meter says 14; when the gauge says what I'd guess to be about 14 v, meter says 14.5, etc.

Good luck!

Rick

Reply to
Rick Courtright

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