Charging System Questions

I am now well equipped with TWO repair manuals and a full toolbox and
a Positive Mental Attitude. Time to go to work.......

I was watching the dimming of the headlight on my Kawie as I engaged
the starter. The headlight is hard-wired to the "ON" position and is
always illuminated when the key is turner to the run position.

That extra load will slow down the starter a bit, shorten the life of
the battery a bit, and slow down the recharging of the battery.

The charging circuit is designed the the headlight load to be there
continuously. Would anything be damaged if I added a switch in series
to leave the headlight off for continuous running? I know it's
illegal not to have a headlight as a running light, but my concern is
that the loss of the load would spike some voltages and then possibly
harm something expensive such as an electronic ignition system.

What say ye, would it hurt to disconnect the headlight for extended
running?

Thanks in advance,

Biker Dude

 

Generations of bikes, in other countries, have had headlights that
aren't permanently on, and have had no such problems.

No. It might even save you a few bucks a year in extended bulb life.

 

It's an 82. So the headlight is supposed to stay off whilst cranking
the starter? Best idea I've heard, will look at the wiring diagram to
locate the exact relay or timer that does this.

When the battery is a bit low it takes too much to energize both the
headlight and the starter.......

Will go to work on this.

Thanks,

Biker Dude

 

On US spec bikes I've owned and ridden, and now on modern EU-spec bikes
(one of which I own), pressing the starter button disengages the
headlight, yes.>

Fit a new battery.

 

I'm pretty sure I've got a Z650 one which will do the trick. I'd
willingly part with it for free as long as the postage is paid.

 

Well, yes, that's my feeling too.

Thinking of lights, the K11 managed to pop two tail light bulbs in the
space of a month recently. No apparent reason. It's been fine since,
but I've got a spare packed in the fairing stash box now. It's got a
warning light for rear filament failure: the last bike I remember that
had that was my old 1976 Yamaha XS650.

And the GN250 needs a new headlight bulb. The interior of the bulb is
all cloudy, like milk, and has a crack, so I assume bulb failure
rather than over-charging. I checked the charging rate, and it's spot
on.

 

Yeah, I wondered about that myself, and checked it over, but it all
seems OK, and it hasn't popped any bulbs in a while now.

 

Some original equipment stop/tail bulbs had a wire support in the middle of
the tail filament.

The last bulbs I bought was a box of 10 Lucas which don't have the support -
but I can remember a time I tried numerous suppliers for the supported
filament types without any success.

 

Oh yeah, I remember them....

 

It'd be pretty easy to cobble up a normally closed relay
for the headlight that opens when the solenoid for
the starter is energized.

 

I know it wasn't the original question but another aspect of this is
that old bikes of many brands didn't charge much at idle, if at all, so
if you were either repeatedly starting or running a non-magneto/battery
ignition type at idle, say while synch'ing carbs or some other
troubleshooting, it was pretty easy to run the battery down enough that
after a dozen or so starts with a fair battery you might have to boost
to start. On my friend's old CB750 which had lots of problems I used to
disconnect the headlight before working on it, but that was a bit of a
PITA. I had a two-dollar switch on a troublesome scooter of mine and if
the 750 had been my own bike, I would have just put a simple toggle
switch in series with the headlight. Some people might complain that
they'd forget to turn on the light after starting, but to me it's the
same as having a side-stand that isn't interlocked with the ignition,
pretty soon you acquire a rote mechanical routine of steps you do before
you ride off, personally I think anybody who does it a different way
every time without thinking will probably have more dangerous problems
when riding, those might be the same people who don't know when their
speedo cable broke or are surprised to be missing a brake at the bottom
of the first hill!

I have a half-baked theory about this. Really good hockey players
always seem to suit up with the same pattern, eg., left skate first or
what have you. I've never seen one step on the ice with bootlaces
undone. I think bikers who have a long record of safe riding are
similar, they will nearly always do the same thing in any given
situation, including preparing to set off.

 

I've got to say I *never* had that problem, and still don't with the old
Honda I steward.

If you have something like a 12A/h battery, which is what my 400 Four
has, and the bike starts easily, you can do an awful lot of cranking on
the starter motor (which draws the most current of any electrical
component) before flattening the battery.

That said, I do remember conking out in London on an old airhead BMW
because its battery was a bit aged and I was running around town all day
on the idle jets with the lights on, and it never got a proper charge.

 

My `01 shadow 750 has the same arrangement . As long as the ignition
switch is on ? the headlight is on.As soon as you push the start
button ? the headlight goes out UNTIL the engine catches and you
release the start button.

Putting a switch in series with the headlight isnt a biggy.It wont
increase the output voltage of the alternator /generator but it will
increase the ability of the charging circuit to recharge your battery
quicker.

Hope this helps
Ed

 

There is a potential problem with that scheme, the battery can drop to about
half voltage under cranking load and may cause the relay to drop out when
you least want it to.

Obviously the weaker the battery the more likely the relay to drop out, and
the more you need it not to.

If I was going to modify a bike so the headlamp was only on when the engine
was running, I'd add a second low power rectifier to the alternator's AC
output, this alone might not hold the relay on while idling at a standstill
in a traffic jam, there is also the issue of excessive output with permanent
magnet alternators, so I suspect a little bit of electronics would be needed
to make it work just right.

 

I could be wrong, but I think a typical arrangement would have the
normally closed relay power the solenoid when it opened and
broke the connection to the headlight.

If your 12 v. battery drops more than a couple volts, it's not
likely to do anything very useful when the solenoid kicks in
anyway.

See above.

 

They certainly exist - those little 2-stroke step-through's of the 70s &
80's used very precarious regulation systems, one I had, the battery (for
indicators, horn stoplight etc) was charged by a single diode from a tapping
on the AC lighting coil. The battery charging current was supposed to
regulate the AC lighting coil but obviously only did on alternate half
cycles - the regulation was flaky at best.

On one occasion I had the battery fuse blow, causing complete loss of
regulation on the AC lighting and instant blowing of every bulb on that
circuit - I was giving it some along an unlit country lane at the time!

 

|>> that the loss of the load would spike some voltages and then possibly
|>> harm something expensive such as an electronic ignition system.
|>
|>Adding a switch is unnecessary. As you say, the bike's charging system
|>is designed to have the headlight on all the time when the engine is
|>running and has enough capacity to charge the battery while running the
|>headlight.

Sometimes the battery voltage will drop to %20/12.0volts and some
even less at long intersection stop lights.
This is somewhat dependant on the ReserveCapacity/Ah high quality of
the battery, and a high quality "spaciality" m-cycle battery is pretty pricy
or rare these days.

My headlights draw 60x2=120 watts from an 8amp starting battery,
needless to say the alarm leeching doesn't help much either.

Adding an inline switch will confuse the ECU/ECM's or general
electronic ignition system's reading and cause an abnormal conflict
somewhere, unless you really know the bikes wiring....and other "fixes".

Good Luck

Bob

 

That'll be a short list, then ;-)