MainePorsche

Guys,

I've done Search but could only find a comment from 2004 that stated he found the headlight amperage to be 'over' 20A when on even after the motor raised them.
Would anyone know the amperage for the headlights when illuminating with an incandescent bulb ?

Thanks in Advance.
Craig

MainePorsche

Remembered my physics. 100 watt bulb will take about 8.3A in a 12V system.

FLYVMO

Stock fuses are 7.5 A per side for low beam, and 15 A for the headlight motor. So if 20A was measured for headlights only, then there is some serious draw somewhere or significantly brighter bulbs must be installed. Possibly it was total draw measured including the tail lights and side markers?

Cheers!
Carl

MainePorsche

Carl,
That makes absolute electrical sense for an 80watt bulb. He must have had those other lights on when measuring.

Alan

Of course it depends on the bulb... And remember you don't have a 12v system when the engine is running. Stock H5 bulbs are 45W low beam (65W high beam). So close to 4A per side for low beam - there is a 7.5A fuse per side.

On initial turn on when the filaments are cold the current will actually be much higher - closer to 40A for a very short period until the filaments reach working temperature, too fast for a normal fuse to react (for the same reason). A fast reading meter with a peak current feature might well capture that. (This is for much less than 1 sec)

Alan

MainePorsche

Interesting.
Alan, does the current to the lights and motor flow THROUGH the relay, or does the Head Light relay just switch the circuit with the current to run the appliance coming from outside the relay ? I ask this for if there is this brief (msec) high amperage involved with the bulbs, might this high amperage ware on the relay over time ? If the appliance current runs through the relay, activating the headlight motor will compound this high amperage exposure too.
Your thoughts...

MainePorsche

Bump for Alan and other Wise Ones.

Alan

There is a different pair of relays for the motor - these are integrated into the headlamp "relay" but they are quite separate from the other 2 relays for the headlamp bulbs (On/Off and Hi/Lo). So the headlamp relay actually has 4 relays integrated into it (only 3 - a single motor relay for the non-reversing pre S4 systems.

Alan

vanster

I take it that an 8" H4 with a 100w high beam bulb ( Low 55w) is going to suck a lot of amps, but since you are motoring along at speed you should be generating enough to not be a problem?

MainePorsche

No, it's not really a problem. I just want to go with more efficient illumination in terms of my alternator output. I'd rather exhaust 2.5 amps with a LED than 8 amps with a 100w incandescent.

Alan

Except you will need new fuses at 8A - and you will be dropping significant voltage over the wiring so you will never really get full power at the bulbs - unless you go to local relays also.

Alan