Charging system ideas?

[dntemp_ca]

Are there any electronic gurus out there that have a fix for the anemic charging system on our XS11's? I had a 750 Ducati in the '70's and they had a weak charging system also. An owners' club member came up with replacing the regulator/rectifier diodes by pressing in new Sylvania diodes. I did that and the charging system improved markedly. I was wondering if that's possible on the XS11 regulator/rectifier?

[stevec5000]

New Rectifier/Regulator

Last week the battery on my XS1100 died, like it does
at the beginning of summer every two years. I replaced
the battery but then found that my alternator would
not charge the battery with the headlight on. With the
light off everything seemed fine, output voltage went
up to 14.5 volts like it should but when the light was
switched on the voltage dropped to 12 volts and
wouldn't go any higher no matter how high the engine
speed. The alternator coils ohmed out OK so I
concluded that the bad battery must have damaged the
rectifier diodes by overheating or something.
I connected an external rectifier bridge to see if
that would solve the problem and it seemed to work
normally. The rectifier and regulator sections of the
stock unit are actually two separate units inside one
housing that share only the ground wire so either part
can be replaced individually by wiring up the needed
part on the outside. Having two circuits wired
together was quite a cludge though so I decided to
make a new unit with modern components. Three years
ago there was a web page by SLHanson that showed how
to wire in a new regulator if the stock one fails. The
web page isn't there now but I saved a copy that I
printed out. He used a Wells VR751 external regulator
module for a VW/Audi alternator. It only has 2 wires
to hookup and I bought one at the time. They used to
be available from Checker, AutoZone, etc. but are not
stocked anymore since they haven't sold any for 15
years so I ordered it from Wells but don't remember
what it costs. Instead of buying a complete regulator
I could have built one from individual parts but used
this unit that I already had on hand. The new
regulator wires in series with the field coil but on
the battery side, not the ground side like the
original, so all you do is disconnect the wires in the
white plug from the coil and rearrange them.
In my case I wanted to add a new rectifier diode
bridge too. It takes a 3-phase bridge which is not too
common and has to be ordered so I used 2 readily
available full wave bridges from the electronics store
instead. They are part # MB356, 35A, 600volt from
Circuit Specialists in Mesa, AZ for $3.50 each and
probably have higher ratings than the stock part. To
use 2 individual bridges all you have to do is wire
the plus and minus terminals together and connect the
3 alternator coil output white wires to 3 of the ac
inputs on the bridges. To make a neater installation I
cut out an aluminum panel to mount the parts on that
fits nicely under the side cover on my XS1100. I also
put an 8 terminal screw type terminal strip on one
side of the panel to connect all the wires to. That
way I was able to get rid of the broken white
alternator connector with it's burned contacts by
cutting the old one off and crimping terminals on the
wires to connect to the terminal strip. I put some
heat sink grease under the 2 bridge rectifiers for
better heat transfer, since they get hot. Their
terminals are flat and can be soldered or they will
accept spade type push on terminals. I had some pieces
of wire from an old washer or some other appliance
that had push on connectors on all the ends that I
used to make the connections by cutting them to length
and crimping a screw terminal on the other end that
goes to the terminal strip. To make sure the housing
of the regulator module was properly grounded I
connected a black wire from one of it's mounting
screws to the ground terminal on the T.S.
Now the alternator works normally again at a cost of
less than $10.00 to build a new one. It only took
about an hour to build and allowed me to clean up the
alternator connectors and I also added a new blade
type fuse holder to the battery.
It still doesn't charge at idle, same as before, but I
found that I have about 1.0 volt being dropped in the
wiring that goes up to the ign. switch from the
battery fuse and back to the other fuses so I'm going
to look into that next. Maybe a Harley style ign.
switch on the side panel?
I took a picture of the completed unit in case anyone
wants to see what it looks like.

[TopCatGr58]

Hey Steve,

This looks like a great tech tip, if you could write it up in more common English for us NON-Electricians, with some diagrams/pictures to show exactly how to put it together and exactly what wires to put where, what parts to get, etc.!?!?!

And send it all to the moderator for the Forum for posting!! Mine works for now, but I had to replace it many years ago when I burned mine up with too many aux. lights running!!!
Thanks, T.C.

[dntemp_ca]

I have a 78E. My headlight is on all the time, day or night. There is a headlight ON/OFF switch on the right handlebar, but it does nothing. I know....'lights on for safety'....but it sure ruins a ride when you push the starter and nothing happens.

Great write-up, Steve. Agree it would be a great tech tip.

[NoVaXS]

Headlight on

Dennis,

I have an E, which I've only had for a short time. When my headlight switch is "on" the headlight is on whether or not the engine is running. When the switch is "off" the headlight is only on when the engine is running.

I've assumed this situation was by design, although the previous owner was quick (and a bit daffy) with a wrench, so he might have modified it in some way.

I keep the switch in the "off" position, but I also have a portable trickle charger harness semi-permanently hooked to the battery and stored under the non-locking side cover, so I don't know how much good the switch in "off" position is doing.

Hope this helps,
Brian

[TopCatGr58]

Off Topic

Hey there Brian/NoVaXS,

I see you live in Falls Church, I'm down here in Portsmouth, Va. Are you planning on going to the XSEast2003 Rally in Pa. Memorial Day Weekend?? A few of us are going to be going up Saturday AM(May24), will be meeting in Leesburg on Hwy15. Welcome to the Forum and the XS11 gang. Drop me a line if you are interested!

Apologies for the Off Topic post!!!! T.C.