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no alternator charge below 50mph. vx model

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hey guys. so i've got a 94 vx with a brand spankin new duralast gold battery. i was cleaning out my tahoe the other day and found my cig lighter voltage gauge. i know its not super accurate for getting voltage loss from a system hitting hard but its nice to know since there isn't a gauge in the dash.


plugged it in and i've been noticing that under 50mph, it seems like nothing is charging. it sits at 12.5v. as soon as i pass 50mph it shoots up to 14.3v and stays there until i go back under 50. i feel like if the alternator was bad, it just wouldn't charge at all. none of this on and off nonsense. is this just a thing the vx models have in an effort to save gas in city driving? or should i look into a new alternator sooner than later?


i'm sure its the original alternator. i also have a 2nd batter in it (been tested as well and its good. only 1 year old) and an RD 1750.1 amp pushing a 12" SA12. i don't really bast it too often honestly so i doubt there is any voltage drop. only reason i threw an extra batter in the back is because i only had 4 gauge and that wouldn't be enough to power my amp unless it was right next to the 2nd battery. which it is. and the 4 gauge to the front is only to charge the 2nd battery. alternator isn't gonna even put out enough charge to need more than 4 ga. will all be upgraded eventually.


for those who don't want to read:

do vx models have a special system that only lets the alternator charge above 50mph?


seems really dumb to me. probably just gonna check out some of dc powers alt's since i really like the only in my tahoe.

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REMOVE SUB, drive that bitch. it goes on about 55 (i think) and if the voltage gets below some amount, probably like 9v or something. how good of mileage are you getting? ive got a vx swap sitting in my basement that ive been looking for a 4dr to put it into... haha im jealous you got one in a car.

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