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Power Window Idea <--- IT WORKS

So if the connections were fixed, would we see similar gains as with relays?

My fuel pump voltage is "low", I've got to figure out why since it's already on a relay. (but thats off topic other than using relays and still experiencing voltage drop)
 
There are 3 problems with the power windows:

1) The wiring is not heavy enough (especially between the two doors)
2) The switches wear out and have too much resistance (I don't know how good they are new)
3) They draw power from the cab fuse block which sees real voltage drop with any load in the cab.

So this wiring upgrade is fixing all three of those problems by using relays. But the point is not that "it's a relay", it's that the wiring is more direct, has fewer contact in the path and uses bigger wire.

If your fuel pump voltage is low, it is probably in the wiring somewhere. The fact that the relay is up front instead of near the pump doesn't matter. Just the total resistance in the path does.
 
Has anyone been using this on a DD that uses the windows daily?

Since doing the headlight relay mod, im burning out low beams all the time. And i dont' drive the truck much. Getting expensive at $14 a pop.

headlights are easy to change, and window motors are not. I really don't want to burn up my window motors.

Any comments?
 
What's your output from the alternator? What is voltage output from the headlight switch?

I'd really expect something else to be out of control if low beams are dying often. Everything in the system should be able to handle 14V constantly, as that is the "upper" limit of the alternators that I've seen. In a perfect world (new) the entire system should see close to that.
 
Thats what i was thinking too. But it doesn't' seem to be the case.

I'll double check the alt output.
What would voltage output from teh switch tell us?
 
What the original system state was...if the voltage was always 11V, but now it's a lot higher, it would at least indicate the higher voltage may be a problem.

I don't expect it SHOULD be, but who knows. Lights may be made cheaper nowadays too.
 
dyeager535 said:
What the original system state was...if the voltage was always 11V, but now it's a lot higher, it would at least indicate the higher voltage may be a problem.

I don't expect it SHOULD be, but who knows. Lights may be made cheaper nowadays too.
Click to expand...

Yah. The original wiring was putting somethign like 11.4 to them, i'm putting about 13.9 IIRC. Gotta upgrade to some housings with bulbs....
 
I had the headlight and power window relay mod done to my Camaro for years. I never burned a headlight out or a relay.

Unless there's some other issue, the relay should not impact the life of the bulbs or motors. Since your alternator output voltage is not unreasonably high, I imagine the problem could stem from contact chatter in the relay causing the lights to flicker. (You may not see the flicker, but this would seriously reduce the life of the bulbs.) Chatter would not be an issue with the motors.
 
Seafarer76 said:
I had the headlight and power window relay mod done to my Camaro for years. I never burned a headlight out or a relay.

Unless there's some other issue, the relay should not impact the life of the bulbs or motors. Since your alternator output voltage is not unreasonably high, I imagine the problem could stem from contact chatter in the relay causing the lights to flicker. (You may not see the flicker, but this would seriously reduce the life of the bulbs.) Chatter would not be an issue with the motors.
Click to expand...

Hm, never thought of that. They ARE cheap relays......i wonder if that is my problem. THe truck rides like a brick, im sure that wouldnt' help said chatter :haha:
 
The motors see a pretty small duty ratio unless you deliver mail on rainy days or something. I wouldn't worry about it. I don't remember if these motor do or not, but many motors in cars have PTC device that shuts them off in the event of too much current for too long. Then you have to wait for it to reset. I would think it would take a lot more than 14V to kill one during one window roll-down or roll-up (and I doubt you'll ever get that much without a fried votage regulator).
 
Seafarer76 said:
I imagine the problem could stem from contact chatter in the relay causing the lights to flicker.
Click to expand...

Do you have any evidence or experience of this? It takes maybe 6V to keep a 12V relay pulled in and you are powering this tiny relay coil with wiring that can support a pair of halogen bulbs. The force on the relay contact must be pretty high compared to the inertia of that little piece. Maybe I'm just not familiar with really cheap relays.

Plus, is chatter that bad? You can run a bulb on AC or DC current and light dimmers in your house are simply chopping the AC waveform off to make lower average current. If his bulbs were truly turning on and off you would think he would notice it.

:dunno:
 
If the relay is chattering you essentially get a PWM waveform. Because filaments aren't solid state (it takes time to heat up to produce light and cool down to stop producing lights), it is possible that the bulbs stay illuminated at a slightly lesser "apparent" voltage. This apparent voltage could be equivalent to or greater than the voltage applied prior to the relay conversion.

Latching relays, or a solid-state relay are the way to go if you want to completely remove the possibility of relay chatter.
 
I was just suggesting another possible cause. A cheap relay may chatter due to vibrations. The chatter is not like a sinusoidal AC voltage. AC typically consists of a single (relatively low) frequency. A chattering relay or chopped signal generates many high frequencies due to the abrupt edge of the signal.

My idea was that the opening/closing relay would shorten the life of the bulb due to rapid cooling /heating of the filament, which in automotive applications see a much higher current than your typical household incandescent (~10x greater). He said he checked the Alternator voltage and it was less than 14v, so there has to be another reason.

(Its not something I've researched, but it's what popped into my head when thinking about the problem)
 
Jagged said:
If the relay is chattering you essentially get a PWM waveform. Because filaments aren't solid state (it takes time to heat up to produce light and cool down to stop producing lights), it is possible that the bulbs stay illuminated at a slightly lesser "apparent" voltage. This apparent voltage could be equivalent to or greater than the voltage applied prior to the relay conversion.

Latching relays, or a solid-state relay are the way to go if you want to completely remove the possibility of relay chatter.
Click to expand...

This is all all possible, but chattering is generally just a problem during the switching events (like contact bounce). If they chatter all the time, then you could actually measure a lower DC voltage at the bulb. My guess is that you would see or hear something if it was much of a problem.

And every car in the past couple of decades has had lots of relays. Now all of the modules are designed to withstand certain levels of voltage dropout, but I still think something like an ECU or even a radio would be more susceptible to these transients than a light bulb.
 
Well, i wired my relays the exact way, and all i get is clicking.
I hear the relay clicking, trying to work, but nothing happens.
Very frustrating, i can wire a relay, and i understand how they work.
 
HarrisonTX said:
Well, i wired my relays the exact way, and all i get is clicking.
I hear the relay clicking, trying to work, but nothing happens.
Very frustrating, i can wire a relay, and i understand how they work.
Click to expand...

Did you wire them according to my wiring diagram posted or another way? You don't wire them in the "normal" fashion for this application due to the ground and power both being switched.
 
The battery direct sounds like a great idea. I have a bag of isolated pass thru studs i bought at frieghtliner that are used to get power and ground into the Medium duty cabs i plan to use for various projects on my 79....ie: large battery direct wire for bass tube....etc. With the isolated studs one can make one hole in the firewall and hook several items to said stud with each circuit having its own individual protection ie: fuse...CB....etc.
I hate stacking two circuits into one acc or batt hole is gm's fuse panel as as a general rule of thumb a fuse is designed to handle 66 percent of the load leaving a 33 percent cushion on said circuit...before melt down.

DW
 
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