Date: Tue, 3 Apr 2007 20:51:03 -0500
Reply-To: Matt Roberds <mattroberds@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Matt Roberds <mattroberds@COX.NET>
Subject: Re: Tail light upgrade question
In-Reply-To: <20070403220845.THUG16968.fed1rmmtai105.cox.net@fed1rmimpi01.cox.net>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
> From: neil <musomuso@GMAIL.COM>
> Date: Tue, 3 Apr 2007 09:49:23 -0700
>
> P.S. I will make sure bulb/socket contacts are clean!
Do this first and the lamps you have already will look even better. It
doesn't take much voltage drop to really kill the light output from the
lamps. It varies a little according to the size of the lamp, but one
"rule of thumb" is that a 5% drop from rated voltage is good for a 16%
drop in light output. A 10% voltage drop gets you a 30% drop in light
output. Your basic 1157 has design voltages of 12.8 V for the bright
filament and 14.0 V for the dim filament.
You can measure the voltage drop in the entire positive side of the
circuit directly with a voltmeter and maybe a long piece of wire.
Turn on the lights. Put the red probe of your voltmeter right on the
positive terminal post at the battery (and/or use the long piece of
wire to extend the red probe.) Put the black probe on the terminal
of the lamp socket you are interested in. If you sprung for the
superconductor wiring harness at rebuild time, the voltmeter will read
0.0 V. (You can also tell by the tanks of liquid nitrogen in the van
that you have to keep filling up.) If you have a plain old copper
wiring harness, you'll see some low voltage, preferably less than 0.5 V.
If it's a lot more than this, you should spend some quality time
cleaning up the connections at the battery, fuse box, headlight switch,
etc.
You can do the same thing on the negative side. This time, put the red
probe on the terminal of the lamp socket, and the black probe (maybe
extended with the wire) right on the negative terminal post of the
battery. This will probably be a lower reading but shouldn't be more
than maybe 0.3 V. If it's higher, start working on your ground jumpers
and ground straps.
> Can someone supply me with numbers (i.e. numbers found on bulbs at
> FLAPS) and/or wattages, for brighter brake, running, and rear turn
> signal light upgrade?
An 1156 (single filament) is rated at 12.8 V, 2.10 A, 26.9 W, 32 cp.
A 2396 gets you 12.8 V, 2.23 A, 28.5 W, 40 cp.
An 1157 (dual filament) is rated at 12.8 V, 2.10 A, 26.9 W, 32 cp bright
and 14.0 V, 0.59 A, 8.26 W, 3.0 cp dim. A 2357 gets you 12.8 V, 2.23 A,
28.5 W, 40 cp bright and 14.0 V, 0.59 A, 8.26 W, and 3.0 cp dim.
These numbers are from a catalog. I don't know what any of these might
do to your lenses; others here can comment better than I can.
You can get "krypton" or "halogen" versions of many of the standard
lamps. A Wagner Lighting catalog I have doesn't claim any increased
light output for these lamps, but it does claim longer life.
Here's something _not_ to use: LED clusters with normal lamp bases. The
reflectors and lenses of the fixture are designed for the filament shape
and location of an incandescent lamp. The LED chips end up nowhere near
the correct location. What usually happens is that you get a very bright
spot aimed directly behind the van, but almost nothing at any angle. The
certification tests (FMVSS 108/DOT/SAE/ECE) for these fixtures include
measuring the light output at several different angles and distances, not
just directly behind the fixture.
If you really want LED lamps, remove the stock VW tail lights and get
some purpose-built LED lamps that are meant to go on a trailer or a big
truck. These are designed to have sufficient light output at all
required angles and otherwise meet the regulations. As long as you
mount them reasonably vertically and not down in a deep recess, they'll
be legal.
Later you mentioned wanting to test some lamps, but your van is somewhat
disassembled at the moment. At the auto parts store, you can get some
battery terminals that have studs and wing nuts on them. Alternatively,
a worm gear hose clamp for about a 1/2" (13 mm) hose works well. Also get
a fuse holder and a 10 A fuse for it, some 1/4" (6 mm) female push-ons,
and maybe some ring terminals. With this stuff and some wire, you can
make up a test rig for wiring your rear lamps directly to the battery so
you can compare them. To connect to the battery, use the terminals with
studs and wing nuts, OR just put the bare end of the wire on the battery
post and crank the hose clamp down around the battery post. Then wire
up some 1/4" push-ons to suit the connectors on your rear lamps. The
fuse holder should be the first thing off of the positive post of the
battery - the fuse is NOT optional! A good battery can deliver about
one zillion amps if shorted and all that energy just loves to melt
things and start fires. Spending $2 on a fuse and holder is cheap
insurance.
Matt Roberds
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