"surging" lights

[ezernut9mm]

when i turn on my lights at night they pulse or surge. regulalor? alternator? bad ground? thanks in advance for your comments/suggestions.-chris

[390Nut]

Check all three, starting with your grounds. They are simple to check, just pull them, clean them, and make sure the wiring is in good condition.

I don't know how to check the regulator, besides putting a known good unit in it's place. Alternator you can drive to most parts places and have it checked in the vehicle while it's running, but chances are they'll tell you its bad just to get you to buy a new one.

Again, swapping in a known good one works as well here.

[67F250CS]

Welcome to the old truck light syndrome. Our old trucks did not have great wiring to the headlights and the way its wired caused the switch to overheat and pulse the lights. What you need is a good relay system. Over in the General Forum there is thread for just this problem. A member is making harnesses with relays for us. He needs 10 orders to do them up. I just got mine from LMC and it does make a huge difference in the power of the lights.

[ezernut9mm]

yeah, i saw that thread. i might be interested. i just thought that maybe my regulator or something was going bad.

[bluef250]

Surging is a common condition as our trucks and other Ford products age. The circuit breaker in the headlight switch gets weak. As it warms, the contact in the breaker opens and then closes, therefore we see surging. Two solutions that I know, replace the switch or install headlight relays.

[ezernut9mm]

Surging is a common condition as our trucks and other Ford products age. The circuit breaker in the headlight switch gets weak. As it warms, the contact in the breaker opens and then closes, therefore we see surging. Two solutions that I know, replace the switch or install headlight relays.

thanks. i'm checking out the relay topic right now.

[F100camperspecial]

I had this problem on my '72 F100 4x4--turned out to be the voltage regulator. I ditched the electro-mechanical regulator for the transistor regulator and no worries since--nice 13.8-14 volts and no more pulsing headlights.

[cghstrojan08]

I have the same problem. How do I test the regulator? or do I just buy a new one. I a going to go over and test the alternator.

[kid]

Start the engine and put a voltmeter on the battery.

If you have 12.4 V before you start and 12.4 after you start the alternator is working, Our old 65A alternator and mechanical regulator does not generate 14 volts at an idle and when tuned only give what the vehicle needs. Recharge the battery 3 Amps, run the headlights 18 Amps so the alternator puts out 21 Amps at 12.5 Volts.

The surging problem will show up if you have an old Analog meter (has a needle) You will see the surge. So check the regulator connectors from the back side and see if the surge appears there. If it does it is the regulator.

[QC]

If you don't have at least 13 volts at the battery when the motor is running, even at an idle, you need a new alt. or voltage regulator. RPM isn't going to change the voltage much, just the amp output. A fully charged battery is 12.6 volts.

[kid]

Both my trucks pull 12.5 at an idle.

A perfect fully charged battery is 2.25 per cell or 13.5V, in reality most if you check them are at 12.2 to 12.7 in the morning before start.

When reaching full charge, the voltage must be lowered to maintain the battery at between 2.25 and 2.27V/cell. That means 13.5 to 13.62

From
http://www.batteryuniversity.com/partone-13.htm

I drive at 13.5 to 14.2

[F100camperspecial]

The other part of this the fact that Ford alts have different field winding ohms reading between alts that used the electro-mechanical volt regulator and the transistorized regulator. Parts stores will often sell you the wrong alt. I ended up with a '77 alt in my truck but the truck had the older regulator. When I switched to the newer regulator all was fine. I'd have to dig the figures out my books around here, but I have seen the same in Mustang II's.

[72hiboy4x4]

Both my trucks pull 12.5 at an idle.

A perfect fully charged battery is 2.25 per cell or 13.5V, in reality most if you check them are at 12.2 to 12.7 in the morning before start.

When reaching full charge, the voltage must be lowered to maintain the battery at between 2.25 and 2.27V/cell. That means 13.5 to 13.62

From
http://www.batteryuniversity.com/partone-13.htm

I drive at 13.5 to 14.2

you are reading that article wrong. He's talking about charging batteries at that rate, not a static charge.
A battery is designed with 2V per cell, 12V per 6 cell. Most batteries end up at (like you said) 12.2-12.7 at rest.
If your charging system is putting out less than 13.3V or so at an idle, there is something wrong. The alt. has to make up for the ignition, lights, fan, whatever is running at an idle, and 12.5V output ain't gunna cut it.

An Alt will reach peak amp charge at about 2000 RPM. So anyone you see trying to jump-start a car who is revving the engine to red-line is just wasting their engine.

[kid]

I am not reading that article wrong I am only posting that article for other people to read along with real world knowledge. Most auto batteries are close to 2.2 Volts per cell or 13.2V which is the design technology of the Lead Acid.

I used to work with Lead Acid single cell battery strings of 24 cells that had the cells set at 2.18 V for 52.32 negative volts DC. Lead Acid batteries in the real world are rarely any value that the books say due to contaminates and intercell resistance. My cells weighed anywhere from 200 to 1000 pounds per cell.

You can set a battery's permanent running voltage by long deep float charges

[cghstrojan08]

OK, I bought a new alternator and that didn't fix the problem. I am going to later today buy a new voltage regulator and try that. If that don't fix it, then what should I try?