Posted by . on May 16, 2010, 8:23 pm
> > So he decided to wind as many turns of copper wire onto the cores
> > as possible,
> heh heh... Maximizing inductive impedance, so output would decrease as
> rpm increased
That's a point I hadn't thought of.
I suppose that experienced electrical engineers who design motorcycle
alternators and rectifier regulators have all sorts of RPM vs. power
output curves for their products and they know what the optimum RPM
and battery capacity is for a *balanced* system.
> Was this back before the days of solid state voltage regulators?
Depends on what you call "solid state." Triumph was using large zener
diodes mounted in radial finned heat sinks in the 1960's and some
Suzukis were also using zeners in little tin boxes that weren't nearly
so obvious.
> Ummm... nevermind, the GT750 did not predate solid state voltage
> regulators.
The GT750 had an electromechanical regulator like a car of the 1950's.
> > The Multifire unit needed 30 amps at low RPM and the current draw
> > decreased as engine RPM increased...
> That explains it. I've worked with engineers that put in lots of extra
> effort, to turn separate problems into interesting interacting
> solutions... I usually had to wait for them to wander off and get
> interested in something else, so I could finally fix the problems they
> caused.
Yup. This particular EE had no practical experience at all, but he had
a lot of ideas that he thought were great.
I wired up the systems he described, but I also set up a stock
ignition points plate just in case his electronic wizardry failed.
We wound up using the points ignition and were running a total loss
battery ignition system on the day of qualifying after mysterious
short circuits caused
the electronic ignition to crap out sporadically...
Posted by No Spam on May 16, 2010, 3:29 pm
I tried to cancel my previous reply to this post... here is something
a little more concise.
> ...the point I was trying to make is that the
> motorcycle's alternator would try to *charge* the partly discharged
> car battery *and* the discharged motorcycle battery, and that
> current would be too much for the alternator windings and the RR
> diodes to handle.
>
The current the motorcycle alternator can produce is limited by the
relatively weak magnetic field the windings are rotating in. The
motorcycle battery has such a low internal resistance that it can draw
far more current than any motorcycle alternator could possibly
produce. Adding another battery into the circuit will have no affect
on the current produced, at all. In fact, a motorcycle battery rated
for a lowly 150 amps of starting current can draw more charging
current than most car alternators can produce from their stronger, but
still limited, magnetic fields.
regards,
Joe
Posted by No Spam on May 16, 2010, 4:09 pm
>
> Also, can I jump start a bike from a car battery - just to be 100%
> sure it isn't the battery. But I am fairly sure it isnt the
> problem.
>
Yes, you can.
Problems can arise when people jump start a motorcycle from a whole
car, rather than an isolated car battery. If the car engine is
running, the car voltage regulator is sensing the state of charge on
the car battery. The state of charge of the motorcycle battery, at the
far end of the jumper cables and through what may be poor connections,
has little or no affect on the car's voltage regulator.
If the car was just started, it's voltage regulator will be passing 15
Volts of charging current, to bring the car battery back up to full
charge. If your problem stems from something other than a weak
battery, your already charged battery could be heavily boiled and
ruined in as little as 30 seconds.
As long as the car engine is not running, this isn't a problem.
regards,
Joe
Posted by The Older Gentleman on May 16, 2010, 5:09 pm
> If the car was just started, it's voltage regulator will be passing 15
> Volts of charging current, to bring the car battery back up to full
> charge. If your problem stems from something other than a weak
> battery, your already charged battery could be heavily boiled and
> ruined in as little as 30 seconds.
Bikes charge at around 13.5v, according to my mutlimeter.
>
> As long as the car engine is not running, this isn't a problem.
Whch is how I always do it.
--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
Posted by paul c on May 16, 2010, 5:38 pm
No Spam wrote:
>
>> Also, can I jump start a bike from a car battery - just to be 100%
>> sure it isn't the battery. But I am fairly sure it isnt the
>> problem.
>>
>
> Yes, you can.
>
> Problems can arise when people jump start a motorcycle from a whole
> car, rather than an isolated car battery. If the car engine is
> running, the car voltage regulator is sensing the state of charge on
> the car battery. The state of charge of the motorcycle battery, at the
> far end of the jumper cables and through what may be poor connections,
> has little or no affect on the car's voltage regulator.
>
> If the car was just started, it's voltage regulator will be passing 15
> Volts of charging current, to bring the car battery back up to full
> charge. If your problem stems from something other than a weak
> battery, your already charged battery could be heavily boiled and
> ruined in as little as 30 seconds.
>
> As long as the car engine is not running, this isn't a problem.
>
> regards,
> Joe
Nice posts, thanks.
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> > as possible,
> heh heh... Maximizing inductive impedance, so output would decrease as
> rpm increased