Is this voltage activity normal ? Power windows lower the voltage big time?
I was bothered by the fact that my voltage meter in the car (not known to be the messiah of voltage truth) drops quite a bit with the power window buttons held down.
I did some testing today and came up with these results.
With the car at idle @ 750 rpm
14.4 - 14.6v No accessories ( lights, a/c) on
14.4 - 14.6v With the lights on , A/c Off- No change in voltage
14.3 - 14.5v With the lights on , A/c ON
13.6 - 14.25v With the power windows pressed down, a/c on max and lights on
14.2 - 14.25v With the power windows pressed down, a/c on max and lights off
What is weird is, I can hear my fuel pump sort of lose power when the power windows are pressed?? Do they need that much power or do I have issues somewhere else?
Also, with the a/c and head lights on, my voltage meter drops to just above the 1/4 mark, but the battery is running at 14.3-14.5v (excellent charge). It seems that the factory meter just shows their is a voltage draw, but not necessarily an undercharge.
As far as i know it is. My neighbor's girlfriend's car was reporting low voltage and would run the the battery dead at night. Turned out the switch for her power seat was stuck on. I figure thats a little bigger motor for the seat, but they were only getting like 12 volts, so I think you're in the clear.
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Cardinal Red '88 GT 5 speed, Cobra Upper/Lower, Dynomax complete Super-Turbo cat-back system, Turbo Coupe Rear 10" discs, 3:73 gears, SN95 Master Cylinder, Summit Racing adjustable proportioning valve, Spec Stage II kevlar clutch, steeda adjustable cable/quadrant, 73mm front calipers, P.A. Performance 130 amp alternator, 99 Contour Electric Dual Fans, Battery relocated, rebuilt 91 T-5, Mass Air conversion
my cars voltage meter is crazy and to top it off i have a electric fan....
click the light on volt meter drops down to like 13...
click the ac and it drops to about 10 and the lights dim
with the fan running and no lights or accesories i see 13 click the lights on and it drops to like 10..
fan heat and lights its in the red and the lights are dimmed... i'm almost afraid to drive at night... lol the car seems to run fine though... its weird... maybe i should invest in a autometer volt gauge...
i have a brand new alternator too...
89lx5o is your alt stock or upgraded?
Mine is pretty much the same way but I have a 120 amp alt.Also running a cooling fan and 3 amps for the stereo system.When the fan is on driving at night the voltage drops so low the amps start kicking off due to low voltage.I still need to go bigger with my alt. in the future.
if your window motors are older, they're gonna draw more amps to operate. also, it's hard to tell if the battery is really good unless you check it under a load. I would use a meter and check the battery voltage while you operate the windows. also, check the battery when you start the car and see how low it drops.
Freddy, If you've got the smaller alt pulley, put it on. You'll get better
charging. The smaller crank (drive) pulley slows the belt speed, and
smaller accessory (driven) pulleys speed the accessories back up.
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1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
Is this voltage activity normal ? Power windows lower the voltage big time? 
