Voltage drops when accesories used | Ford Explorer Forums - Serious Explorations

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Voltage drops when accesories used


Explorer Addict
April 30, 2009
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City, State
Spokane WA
When I turn the lights on, roll the windows down, turn signal or anything the voltage will drop some on the guage then come right back up. Was wondering if this was normal?

The battery tested good. I just replaced the alternator and it was doing it before the alternator was replaced. Battery terminals are good. Grounds on the left next to battery seem good.

Is this a problem or normal?

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Where does your gauge sit on a normal day (no ac/heat on, no lights on)
It should be somewhere around the "A" in NORMAL

Its normal for the gauge to drop a bit when rolling all the windows down, thats quite a power draw...and if your lights even make it drop for a sec, that seems a little unusual but I dont think its anything to worry about, how old is your battery? They could test it as being GOOD but a new battery could give you so much more power...

Batter is a little older and a little small for the X I think. Think I'll redo grounds and check all cables sometime. I'm just nervous about the "new" (pull n save) alternator going **** up because of something the system is doing to it. Voltage sits good at idle.

Id almost guarantee its your battery, specially if its small, its not gonna be able to put out the amps it should, therefore putting more stress on your alternator, nothing SERIOUS, but if you can afford like 90$, run to AutoZone, and get a Duralast GOLD battery, its pretty much the best bang for the buck, unless you can afford the $200+ Optima's.

My old battery was supposedly only a year old (bought the explorer right before winter) and the battery just kept dying from the cold, like 20* outside and it was dead, had NO power, I even had a big Kinetik car audio battery that it would kill with it.

Got the new Duralast in, and when it was even below 0, my truck started right up, cranked like there was no tomorrow, no struggling, no nothing.

I have a '94 XLT and it d0se the same thing. My n0rmal is not at the "A" to it is in be tween the r and the m, and i dont have any problums. you should be fine.

Mine sits between the M and A, then drops when I roll down the windows. Then jumps back up as soon as I let go of the roll down button. Certain other things make it dip for a moment, the it comes right back to "normal". I don't worry about it a bit.

Thats exactly what mine does. I'd like a new battery but unfourtunately it's car parts or gas for the boat to go fishing!

just my two cents, had the same problem, ended up putting in my redtop, and adding a ground wire, 4 gauge ground to the terminal and it stopped, thought it was the alt, but had it tested.. and even yanked the battery with the car running.. and it kept running

This is normal since the internal voltage regulator will only apply full voltage to the field when it's necessary, but isn't capable of making more voltage than it has applied to it. The only way to do this is by using an DC to DC converter which inverts voltage to step it up, then bring it back down to the necessary level. It's similar to the PWM power supplies in desktop computers to maintain a rock steady voltage level.