Dim Lights At Idle

[steptoe]

I read a post somewhere that you can eliminate dim lights at idle by installing relays to the headlights. For some reason the old Chrysler cars had wiring issues and the lights would dim at idle even on cars equipped with alternators. For example, the voltage at the battery and also the battery post on the back of the alternator may be in the 12-14 volt range but the voltage at the headlights would be less. This was because of the alternator, wiring, connections, headlight switch, dimmer, etc. The lights would brighten to normal as engine speed increased.

I installed 2 fused relays (1 for low beam and 1 for high beam) and now the headlights get their power directly from the battery. The voltage now travels a much shorter distance and passes directly from the relays to the headlights. Nothing else to interfere or draw current flow. It works beautifully with my factory headlights and can't wait until I get a pair of Sylvania Silverstars to really brighten things up.

 

[dustertogo]

Hey Steptoe,

How bout some more info on the upgrade such as part numbers for the relays, where you got them, and maybe even a diagram of how you hooked everthing up. This sounds like something I'd like to do.

BTW, how does it look like the turnout for " Cruisin the Coast" is going to be this year?

 

[steptoe]

Robert. I bought my relays on the internet over a year ago and don't remember where. However, you should be able to get them at any auto parts store (Autozone, Advance, Napa, etc). They are just 4 or 5 pin SPST 30 AMP relays. Very common. I used 2 relays - 1 for low beam and 1 for high beam.

I bought relays with the pigtails (wiring harness) attached. They also have a mounting tab attached to secure them to the car. I will take some pics of my installation tomorrow and post here for you. I am using 20 Amp circuit breakers instead of inline fuses as shown in the attached diagram. I have one breaker for low beam and the other for high beam. If you blow a fuse you will lose your lights - if a breaker trips it will automatically try to reset. I now have some really bright headlights and no load on the headlights or dimmer switches.
Here's the diagram:

 

[steptoe]

I forgot, Cruzin the Coast started today with about 3500 cars signed up. They expect another 1000 to sign up tomorrow. The weather is perfect. It's gonna be awesome. David

 

[C130 Chief]

Better to take the feed directly off the alternator rather than the battery. This will remove the headlight load from the charging circuit. Especially important if you upgrade to higher wattage lamps and wish not to fry your ammeter. Same goes for stereo amplifiers.

Dim lights at idle are typically a symptom of poor grounds. Clean the headlamp grounds and make sure the chassis ground is in good shape.

 

[ted_sweet]

run a wire with a fusable link directly to battery from alternator.

 

[dustertogo]

Thanks David and guys for the info. I will definitely check for proper grounding also.

Pics of your installation would be helpful David......thanks.

 

[steptoe]

Here are 2 pics of my installation. The pics are kind of small but you should be able to get the idea of what I did. Some one suggested to connect directly to the alternator but I don't see any advantage because ALL power in a car always comes from the battery. No matter what is using electricity, the battery supplies the power - not the alternator. The purpose of the alternator is to replace the voltage drain on the battery (keep it charged). This is one reason you cannot disconnect the battery while the car is running or you will destroy the alternator quickly. It is also another reason to always recharge a dead battery rather than jump starting it and allowing the alternator to recharge it. Instant alternator death is a very likely possibility. If you don't think so, read the installation instructions packaged with your new or rebuilt alternator.

 

[Dart Advantage]

Chrysler did some stunt in at the intro of the alternator,
where they started the car, took out the battey and made some big drive
to point out the reliabilty of the alternator.
That was a mechanical voltage regulator, not the solid-state.

THE MAIN REASON for dim lights, low charge at idle is the "hi-current"
alternator. Look at the windings you can see through the slots.
See the coil loops? Factory units had 12-13 turns per loop, of smaller gauge wire, not the 7-8-9 turns of heavier wire seen in all modern types.

Each leg of the alternator's winding develops less voltage per rpm since its over-all length is shorter than if wound as in the original design.
Your regulator calls for maximum current to the rotor, but even this is not enough to "regulate" at low RPM.
I've had stators custom wound at motor shops get good output at idle.
The large wire-few loops versions should be able to deliver more current
at hiway speeds, but there's hardly any need for it, since we see the ammeter
near the middle most of the time anyway.

I think it's all due to being able to wind 'em cheaper with fewer loops.
Or a conspiracy against mopars by the evildoers.


I added such a relay for the AC fan, where I appreciate the difference and am sure it would brighten the lights quite a bit. But the low output at idle is the evil modern alternator winding style.