boschelreg.htm-22
NOTE: I put this article on this website because a
FEW people asked for it. I suspect few will modify the
METAL CAN electronic regulators. You can purchase an
adjustable voltage regulator quite reasonably from
http://www.RockyPointCycle.com. BUT...the BOSCH and Wehrle
METAL CAN Electronic Regulators, which are essentially identical,
ARE relatively easy to modify, so, go ahead if you wish-to!
YES, there are metal can regulators that have a Wehrle label on top, the one I have
seen is stamped with a model E 1051 B/14V. Made in Germany.
These regulators have a similar circuit to the Bosch regulator which is what the
following procedure is specifically for. This Wehrle metal can regulator
has the same sort of circuitry and adjustment control inside. It might
even have been made by Bosch. The exact same procedure is involved....and
the same hole drilling, etc.
This is a how-to article, the purpose is to make your Bosch ELECTRONIC metal can unit 'adjustable'. This is NOT for the similar but larger mechanical Bosch regulator...see BOSCH METAL CAN MECHANICAL VOLTAGE REGULATOR. That is a hyperlink to that article. Elsewhere's on this website will be found an article on increasing the voltage output of the Wehrle electronic regulator. Yep, another hyperlink.
This article applies to BMW Airhead Motorcycles, but is also applicable to any other vehicles that use these models of metal can voltage regulators.
There are numerous ways to increase the
voltage, which is the usual desire, including adding a tiny
diode, but the method described below makes it fully adjustable.
Don't
attempt this if you can't work on small parts and use a
small soldering iron comfortably. You MAY not need the soldering
iron.
Parts needed:
1. One rubber grommet....no special size, from Radio
Shack or ? One with a 3/8" mounting
hole is fine, so is one of 1/4" or 5/16". The 3/8" or even
a 1/2" might be better if you are not good at making measurements on where
to drill....so
read this procedure through. You don't HAVE TO have this part,
but you probably will want it. You will also want a common black plastic
body plug that fits the center hole...or, you could use tape.
A plug is
nicer. RTV cement is nice to
seal the plug so it stays in place.
2. A few Q-tips and some acetone or similar strong
solvent.
3. Small jewelers screwdriver.
4. Drill bits.
5. 100 ohm potentiometer...in case you ruin the existing
one; then you'll need a small soldering iron and bit of 60/40
electronics solder. A
potentiometer is a small variable resistor used in electronics, and
if you need one, it would need
to
mechanically and electrically fit the existing regulator, many common types
fit just fine, some with very minor work. If you are careful, you will NOT
need this part....and in any event, Radio Shack or most any local
shop will have them.
The electronic metal can voltage regulator consists of a number of
transistors,
diodes, resistors & capacitors, the purpose of which are not
important to this article.
Modification:
1. Remove the regulator from the bike. There are two
allen head screws, and a plug to
disconnect. You don't have to remove any battery connections.
2. Remove the tape from the regulator that keeps the
top can from coming off.
3. Gently wiggle the top can off the base, these can be on tight,
so work slowly.
4. Inside you will find a printed circuit board with all
the components mounted upside down...that is,
underneath the board. On the end of the board
OPPOSITE the plug/socket end, you will find a small
electronic device called a pot (short for
potentiometer). This is the factory adjustment
control. Every one I have seen is always sealed with a drop of a hard to
remove white paint.
5. Try to remove or at least release the paint with repeated soakings of a
q-tip in something like acetone, or paint remover
(?). This can take some
time. If you are successful, the pot will be usable as
is, and can be adjustable. If you are not
successful,
you can try VERY GENTLY prying a tiny bit at the
paint, to free up the lower adjustment fingers metal
ring. Do NOT pry much. If you ruin the pot, it will
have to be replaced, with any common 100 ohm
pot that fits, or can be made
to fit. I have found it best to CAREFULLY unsolder the three
legs of the
pot and remove it, and soak it in acetone for a short
while....which ALSO gives me SAFE access to
ENLARGE the very tiny hole for the adjustment, that
is stock, on
the board. If you are VERY careful you
could leave the pot in place and drill out that hole by
hand...just don't ruin the pot. **You don't HAVE to drill
the tiny hole larger, but you will need a VERY TINY jewelers screwdriver for the adjustment, if
you
do not....so I DO recommend drilling the
board hole larger. What size? Whatever you wish, to
match your jeweler's screwdriver that FITS THE POT SLOT.
6. Assuming the pot is operational, or the replacement
is installed, and the circuit board existing hole is enlarged for access by a
proper sized jewelers screwdriver, you have an
optional step now: That is to drill the thin metal
cover in the
appropriate place, and install a rubber
grommet. The purpose of the rubber grommet is to
keep you from shorting the pot metal to the regulator
cover metal when adjusting the voltage regulator. You don't have to
have the hole and
grommet, you can set the regulator without the cover on.
I vastly prefer the hole/grommet, for convenience. Elsewhere's on the website is information on generically measuring the set point
of regulators. testingvoltageregulators.htm
At the end of THIS article you are reading is a bit of information on adjusting, via a simple method. I suggest you disregard, after reading, the above hyperlinked article and that you DO drill the hole! I also suggest you don't try to do the bench test information at the end of the article, unless you are the nerdy technical type with an adjustable supply, ETC.
You WILL find
the hole convenient!... for future adjustments...if you change the battery to a
type needing a different voltage, ETC.! NOTE that if you use the
grommet, it is nice to seal it's hole with something. I use a common black
plastic auto-body plug, that fits into the center hole, and I use a wee bit of
silicon rubber...that stuff in a squeeze tube. Easy to remove and readjust
whenever you might like to.
7. Be sure all is assembled correctly if you removed the pot.
Re-check your work. Install the cover, be sure your
jewelers screwdriver will fit the tiny pot slot and
operate the pot. If you are worried about the pot
being OK, you could use an
ohmmeter on the pot and prove that the pot is
about 100 ohms between the ends, and that the wiper, with respect
to either end, works properly, before re-installing the metal
cover.
8. Reinstall the cover tape and install the regulator on your bike and plug it
in.
9. Adjustment of the regulator is, of course, by the jewelers
screwdriver, making SURE the metal of the jewelers
screwdriver canNOT contact the metal can. The
screwdriver MUST be the right size, or you will ruin
the pot. Be gentle in any
downward pressure.
10. The voltage setting depends on your usage of the
bike, and the type of battery, and the temperature
of the regulator when making the adjustment. The
regulator is temperature compensated and DESIGNED to INcrease its voltage
ver
slightly as the
temperature of THE REGULATOR goes down.
Some guidelines:
I will assume here a 70°F day, engine started and regulator
adjusted within a FEW minutes (so the regulator has
NOT warmed up from engine heat), and that the battery is
fully charged to begin with...with only the starting-up
drain, and the bike at perhaps 3500-4000 rpm for a
minute or so....or, the battery voltage is no
longer rising from recharging the battery:
For common flooded
batteries, a good compromise between water usage and charging is 14.1 optimum, range 13.7-14.3
For other temperatures at the regulator can when you adjust it:
For 47°F 13.8-14.4
For 93°F 13.6-14.2
For 117°F 13.5-14.1
Those doing commuting, stop and go and city driving
probably should use the higher end of the above ranges, or
even 0.2 volt more.
NOTE: It appears that the sealed AGM/VRLA types of batteries may like a slightly higher voltage. I am presently suggesting 14.5 volts at 70°F. Stop and go commuters could try as high as 14.9 at 70°F....but that is really an absolute LIMIT.
NOTE!!! All voltage
readings are taken AT the BATTERY terminals themselves!!, and NOT
from your fairing
voltmeter!!! You must have an accurate digital voltmeter.
Your battery connections must be clean, solid, etc.
Bench Test method for those having an adjustable power source, and
wanting a 'bench' test:
Keep in mind that this is NOT a test ON the bike, but with the
regulator on your workbench....seems self-evident, but have had some confused
readers!
I use an old headlight lamp as a load, but almost any
lamp or 5 to 20 ohm resistor will work (power resistor of
10 watt rating is OK for short term testing). Frankly,
it is FAR easier to use the lamp!
Before you start here, keep in mind that
you should start connecting things with the power source turned
OFF, and you should recheck the connections several times BEFORE
turning on the power source. DO NOT connect anything
wrongly!
Connect one
side of the lamp to the terminal marked DF, and the
other side of the lamp to the power source negative. Connect the D+ terminal to the power source positive.
Connect the power source negative to the D- terminal.
Connect the digital voltmeter to D+ and D-, trying to make a good
connection that does NOT include any voltage drops from other
connections at those points.
Raise the voltage VERY slowly. As the voltage rises, the lamp
will start lighting up. Continue to raise the voltage very slowly. The
lamp will suddenly go OUT. Note the voltage
AS CLOSELY as you can JUST BEFORE THE LAMP
GOES SUDDENLY OUT. Retry SEVERAL times, lowering the voltage and start raising it
again, slowly. You must be careful and accurate as
possible. Your adjustable supply may increase in voltage
when the lamp goes out, so try to get the exact voltage when the
lamp is as close as possible to going out, but hasn't, yet. Adjust the pot to where you want the voltage, install the regulator into the motorcycle as
noted, and make final adjustments if you have to.
Revisions:
01/16/2010: all prior rev. included. Minor cleanup
05/18/2011: Revise to show that the Wehrle are the same,
plus a few minor updates and clarifications.
© Copyright, 2011, R. Fleischer