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Topic: Relay modification Headlamp and Marker lamp *pls review (Read 6399 times) previous topic - next topic

Relay modification Headlamp and Marker lamp *pls review

Reply #15 –
Quote from: TOM Renzo;395966
Note you might want to reconsider the relay locations under the hoods. Here is why!!!
Well, this looks like relay soaked in ocean water. I saw this just once, on the old car sitting on the water reservoir beach for many years (not in the water, just next to), so I'm not worry about this problem on most cars, if you put the relays on some good place.

And the answer to your previous question - Yes, I've measured the voltage drop on the car I modified for my good friend. He has '69 Caddy Eldorado and the volage drop on that car was over 2 volts when the lights were powered just by the battery. All connectors were clean, just for sure.
The difference in brightness after this mod is huge.

Relay modification Headlamp and Marker lamp *pls review

Reply #16 –
my 2c on voltage drop as well.

"when" the atlernator fails and it will", the voltage goes down and therefore the current goes up.
in short order those reliable wires become very questionable at 10 or 8 vdc.

under normal cirumstances i would agree the wire is good enough.
duirng cranking of the engine with auto lamps on,, and the car seems to be cranking sluggish or hard to start, those wires are suffering from irratic voltage drop during that event as well.  there are several events the could exceed the limitations of the wire but yes under normal operation and working conditions, the wire should be ok.

i do like reducing the power feed to the lights by 50% thier actual distance now though, its like a 12' run from the lights to the switch.  3 to 6 feet sounds tempting.

Relay modification Headlamp and Marker lamp *pls review

Reply #17 –
All approve of the two drawings ?

Relay modification Headlamp and Marker lamp *pls review

Reply #18 –
I noticed a temperature increase at the headlamp switch when I moved up to a higher wattage bulb in my Coupe.  I installed two relays, one for low and one for high beam using the low and high beam outputs from the multifunction switch to trigger the relays.  The temperature at the head light switch is still noticeably less and the light output increased.  I think it is a great modification for higher output bulbs.  I did this on my Bird as well when I converted it over to the H4 bulbs as the older style head light switches are notorious for over heating with the higher amperage loads from the newer light bulbs.

So I guess what I am overly tiredly babbling about is that I think this is a great sticky it!

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Relay modification Headlamp and Marker lamp *pls review

Reply #19 –
darren
You did what i drew up in the second layout but can you explain if you have auto lamps or not?

Relay modification Headlamp and Marker lamp *pls review

Reply #20 –
You know if the headlight switch is getting hotter with bulbs that draw more current???? Then the weak link as i point out many times before is the switch. So keep over designing circuits if you feel you must. And i find it hard to believe a voltage drop oe 2 Volts. Because i have only shown app .3 Voltage drop with a relay that slaves the switch. Be it as it may i will bail out of this discussion and hope to god i never have to shoot a trouble in one of these modified setups. Basically you guys are over thinking this and designing circuits that are way to complicated and not worth bothering with. That relay came out of a car at the show and was no where near the OCEAN. He had a headlight relay kit he bought and the under hood relays were corroded. Best place for the relays are in the cab or trunk. But i have a question??? If you use battery voltage from the cars battery to the relay to prevent voltage drop!!! Then what do you do if you have a trunk mount battery???  I find it very difficult to believe a 2 volt drop with the headlight switch fed with a number 12 Gauge multi strand wire. That wire can handle over 30AMPS + and a pair of headlights draws 12A. Very confusing to me. Thanks!!

 I installed two relays, one for low and one for high

WHY??? YOU ONLY NEED ONE RELAY FOR HIGH LOW!!! The 5 pr0ng relay has two positions!!!

Headlight Circuit- 14 GAUGE    

Headlight Switch To Fuse Block- 12 GAUGE
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Relay modification Headlamp and Marker lamp *pls review

Reply #21 –
Certainly your not pointing at me over complicating anything because if you are,,, you have your work cut out for you : )

I cant see anywhere that I over complicated any part of the structure, infact i show the very drawing you suggested ,, then went further to offer optional dual relays down stream of the M/F switch so the heat load on both the main and M/F switch is greatly relieved.

what is the issue you have with who's layout and why,, thats called progress which helps us all do a better / cleaner job.  thats all that matters at the end of the day.

maybe your just in one of those moods or something, either way i take no offence, i just need to know how your comments above are substatiated when the OP shows exactly what your endorsing.

Relay modification Headlamp and Marker lamp *pls review

Reply #22 –
No auto lamps, my car is the old style pull  on the headlight switch.  The stock head lights on my '83 were fairly low wattage, 50W for high beam and 35W for low beam.  The H4 bulbs I put in the new headlamp fixtures are 100/90 Hi/Lo.  So some simple math and the load on high beam with the old style lights was 190 Watts total.  The load with the new H4's is 400 Watts total.  Hell even on low beam the old lights were 70 Watts total and the new H4's are 180 Watts total.

Watts / Volts = Amps

Old Head Lights:
190/12 = 15.8A (Battery Voltage) or 190/14.4 = 13.2A (with the engine running and alternator charging)

New Head Lights:
400/12 = 33.3A (Battery Voltage) or 400/14.4 = 27.8A (with the engine running and alternator charging)

For me the stock wiring was marginal at best with the stock loads and with the added power of the newer lights I thought relays were a prudent move.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Relay modification Headlamp and Marker lamp *pls review

Reply #23 –
WOW this is what i mean!!!!

A 60-watt halogen bulb draws 5 amps of power @12 volts. Times 2 equals 10 amps of load. Most high beam lamps are 60 - 65 WATTS

Watts = VOLTAGE X CURRENT

So a pair of headlights running at app 14 VOLTS draws app 14 AMPS on high beams.

A pair of 100WATT lamps at 14 VOLTS would draw 16 AMPS  NOT 33.5 amps?????????


14 VOLTS X 8 AMPS = 102 WATTS X2 lamps = 16 AMPS of load.

With 4 headlights it would be 32 AMPS. So one 40 AMP relay would suffice!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Relay modification Headlamp and Marker lamp *pls review

Reply #24 –
Tom,

With my '83 all four of the headlights come on for high beam which I believe was standard on the four eyed cars.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Relay modification Headlamp and Marker lamp *pls review

Reply #25 –
and since most of this wire is in bundles and inside a corelon flex tube, 
and since most none of this wire has any rating for insulation or temp,

we have to assume "in raceway or wire way" and at 60degC.

that being said, you should also factor in low voltage conditions of approx 10v if you wish,, then you would conclude to the amperage and size the wire to that ampacity along with the fuse.

then  yes as i have agreed to also, the wire seems a tad marginal... under normal conditions, i still would not engineer most of these circuits like this.

these are just my thoughts, thats all.

since you have the pull switch, im sure you would not have headlamps if your MF switch failed.
tom makes a good point of catching the high beams at the main light switch with a slave relay.

maybe this is a fail safe solution for people without auto lamps...
slave the high beam like he said downstream of the main light switch
slave the lows downstream of the MF switch

again, the second relay would be opitonal in some peoples opinion.

tom
you made a statement,
are  you saying to use one slave relay (designed with one contact set NO and one contact set NC) downstream of the main light switch...
wire low beams off the NC contacts
wire the high beams off the NO contacts

when high beam is selected, the relay is energized and the hi beam contacts are picked to power Hi beam?
this specifically is what i wanted to talk to you about.
i thought when hi was chosen by the user,, low beams stayed on but the additional HI beam element also got power...
how can what i described above work if both elements are needing energized to achieve HI beam?

Relay modification Headlamp and Marker lamp *pls review

Reply #26 –
Ok first off older cars have 4 HIGH BEAMS. That is a given. But low beams are 2. With that going to a 100W lamp you have to times it by 4 as noted by aerocoupe. So with 4 high beams you need a heavier relay and or 2 if you want to split the system?? Either way the system as stock wiring was never designed for doubling the current. But normally the switch is wired with a number 12 wire. That can easily handle the load of 4 X 100 LAMPS ON HIGH BEAM. And yes NC and No is how the 5 pr0ng works. So with normally closed contacts as low and NO contacts as high only one relay is required. Hope i explained it OK. With a 4 eyes and 100W lamps you would benefit with 2 relays and split left and right. BUT 100 Watt lamps are illegal any way so with that we use Ballasts and HID which draws much less and gives more light. WOW what a discussion!!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Relay modification Headlamp and Marker lamp *pls review

Reply #27 –
I get it now,,

i guess i dont know how the bulbs work,,lol

tell me if i am wrong here..
low is selected and then when Hi is selected, low beams stay on but the second element is illuminated.
from what you are saying i am wrong.

what you are saying is Low is selected and then....
when high is selected,, lows are off and HI is on only?????????????

what say you >?

Relay modification Headlamp and Marker lamp *pls review

Reply #28 –
Quote from: jcassity;396357
tell me if i am wrong here..
low is selected and then when Hi is selected, low beams stay on but the second element is illuminated.
from what you are saying i am wrong.
Yep you are wrong.

Quote
what you are saying is Low is selected and then....
when high is selected,, lows are off and HI is on only?????????????
Yes this how they work. Only one bulb element is on at a time.

Relay modification Headlamp and Marker lamp *pls review

Reply #29 –
well,, learned me something new...
i had it wrong for along time.  If i had known that, i naturally would have wire both low/hi to the single relay like****someone**(tom) ** was sayin,, : )
makes perfect sense now to use one relay...lol  and pick it right after the main headlamp switch