re: She cannah take tha' mooch pawr-r-r, Cahptain!

["Tony Sims" <simstony@domain.elided>]

David writes:

>Esteemed ALFA Colleagues,
>
>Correct me if I'm wrong (surely someone will) but by the description of the
>circuit it seems to me that
>the only current carried by the high beam circuit is coil current for the
>relays which should be mA.
>The bulk of the current is carried buy the individual wires, fuses and
>relays for the headlights and Aux
>lights themselves. If this is the case there should never be an instance of
>blowing the high beam circuit.
>I agree with whomever suggested 10 AWG wire for 30 Amps but 100W/12V=8.3 A +
>75W/12V=6.25 A
>for a total of 14.58 A per 20 Amp fuse and 12AWG wire,  all worst case @
>12V, sound reasonable?
>Now, with 12 AWG wire easily good for 20 A there is no problem in this setup
>other than for some reason
>the relay coil current appears to be exceeding 20 Amps ????
>Unless there is a short or some sort of miswire. The only fuses that might
>blow are the two feeding the lamps
>but they shouldn't unless there is the aforementioned fault.
>I've heard no mention of them blowing, only the main headlamp circuit.
>Wiring Check!

This one's prettty much over, but for those who missed the note in my second
post, the car in question was not an Alfa, it was one of my other cars.  I
should have made that clear up front, because I know many people were trying
to refer to Alfa wiring diagrams.

This car had no fuse in the critical part of the high-beam circuit
(battery-relay-lamps) before I revised the wiring, leading to a meltdown of
the original 32 year old 14awg when one H1 bulb was connected with +/-
reversed (don't ask).  Now it has 2 fuses, one in each line feeding power from
the battery to the relays for the low- and high-beam power circuits.  The
switch signal for the new low-beam relay comes from the original power wire
that ran from the headlight switch to the lamps.  The original high-beam power
circuit had a relay.

The fuse that is blowing is the one between the battery and the high-beam
relay.  I've received numerous messages about this issue, and it's clear I
need to revise my original installation of the main power circuit for the high
beams, because it's not sufficient for the 350 watts I'm asking of it.

It am going to split it so there is a separate main power circuit for left and
right high-beams, and I'm going to upgrade the ground (earth) side because my
first attempt was shy of sufficient.  I'll have it down to a little under 15
amps per side, which as noted above will be fine with 12awg wire and the 20
amp fuses.  In the short term I just unplugged the H1 lamps and am getting by
with "only" the 75w high-beam in the H4's.

Tony
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