Date: Thu, 4 Dec 2008 18:04:19 -0800
Reply-To: David Marshall <mailinglist@FASTFORWARD.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Marshall <mailinglist@FASTFORWARD.CA>
Subject: Re: Headlight Upgrade
In-Reply-To: <2cb866ef0812041701i10c380c1p9edf0d34e535ccc7@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
In short the more current you have the more voltage you will loose due to
resistance in the wires. Install fat wires with fat bulbs and you're
set with brighter lights.
In long we can use Ohm's law:
V = I x R
P = I x V
Where:
V - volts
I
- current
R - resistance
P - watts
So your 100W bulb
(really 200W as two lights) is rated 200W @ 13.8V so current is:
200W = I x 13.8V
Current is 14.5 amps
Wire has
resistance as is a part of the equation. The larger the wire the
less resistance to current flow. So say for example 18 gauge wire
from the battery thru the fuse panel and what have you to the lights is
0.01 ohms (not correct but good for the example) and the installing a 10
gauge (fatter wire) wire from the alternator to the lights is 0.001
ohms
The formula for power loss is PowerLoss = Current^2 x
Resistance
Those lights need 14.5 amps, squared is 210.25 so
210.25 x .01 for the 18 gauge = 2.1 Volt loss
210.25 x .001
for the 10 gauge = 0.21 Volt loss
David Marshall
VW
Adventure Driver and BMW Adventure Rider
http://www.hasenwerk.ca
On Thu, December 4, 2008 17:01,
Jonathan Poole wrote:
>
> I know that many on the list
have made these improvements but I thought
> someone may still be
interested in the improvement and specifically the
> voltage
increase at the headlights that I achieved through the use of
>
Frank
> Condelli's relay kit and by running a 10 gauge power
supply from the
> starter
> to run the headlights.
>
> Before the above listed changes I was getting about 11.9
volts at the
> headlights with the engine idling. After the
changes I get about 13.1
> volts
> at the headlight with
the motor idling.
>
> This upgrade plus putting in the
100/80 watt bulbs and aiming all 4 of my
> headlights (south
african grill setup) has resulted in a dramatic
> improvement of
night driving visibility. I had a shop aim my headlights
> last
year but they did a very poor job and the lights were way off.
>
> Before these changes driving under low beams only was a strain
due to poor
> aiming and dim lights. It wasn't as bad as my old
6v beetle used to be
> but
> in some situations I think it
could be considered dangerous or at least
> annoying. Another
benefit of this modification is that my batteries
> (house
> and starting) maintain a higher voltage since the headlights pull
from the
> alternator instead of the batteries. There is still a
drop when the
> lights
> are on but it is lower.
>
> relay kit and bulbs:
>
http://frankcondelli.com/hdltrela.htm
>
> aiming
guide:
> http://www.danielsternlighting.com/tech/aim/aim.html
>
> I picked up 25' feet (more than is actually needed) of
stranded 10 guage
> wire at the local Lowe's and misc crimp on
connectors at the local auto
> parts store. I ran the wire
without dropping the gas tank. Getting the
> wire over the gas
tank involved sticking a coat hanger over the top of the
> tank
space and then taping the wire to the hanger and pulling the wire
> through to the other side of the tank.
>
>
> Jonathan Poole
> '83 AC Westy
>
>
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