From: The Older Gentleman on
.. <an.gleann.mor(a)gmail.com> wrote:

> On May 16, 10:00 am, No Spam <nos...(a)dont.bother.gov> wrote:
> > "." <an.gleann....(a)gmail.com> wrote:
> >
> > > But the alternator might be damaged when using a partly discharged car
> > > battery to jump start it.
> >
> > Not hardly, unless the voltage regulator and the rectifier diodes are
> > shorted. They isolate the alternator windings from reverse current.
>
> While that's true, 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.
>
> Other items that could be damaged are the plastic connectors from the
> alternator and the RR to the motorcycle wire harness. They *melt*
> under heavy load.

Might, could... It's never happened to me, or anyone I know.


--
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
From: Rob Kleinschmidt on
On May 16, 10:29 am, totallydeadmail...(a)yahoo.co.uk (The Older
Gentleman) wrote:
> . <an.gleann....(a)gmail.com> wrote:

> > Other items that could be damaged are the plastic connectors from the
> > alternator and the RR to the motorcycle wire harness. They *melt*
> > under heavy load.
>
> Might, could... It's never happened to me, or anyone I know.

"Heavy load" as in starting the motorcycle ?

If one were to connect an automotive battery to
an already shorted system, bad stuff might happen.
Only thing I might worry about would be a system
with a totally dead battery.

Since the system isn't shorted and the battery still has
a charge, I personally would go ahead and jump it.
Others should make their own decision.

From: The Older Gentleman on
Rob Kleinschmidt <Rkleinsch1216128(a)aol.com> wrote:

> Only thing I might worry about would be a system
> with a totally dead battery.

*Shrug*

I left the parking lights on overnight on my Triumph Street Triple
a few weeks ago, and jumped it off the Subaru. No worries.


--
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
From: The Older Gentleman on
No Spam <nospam(a)dont.bother.gov> wrote:

> "." <an.gleann.mor(a)gmail.com> wrote in
> news:a1a87efb-06b2-4801-9540-0135e7e928c8(a)11g2000prw.googlegroups.com:
>
> >
> > ...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 alternator can produce is limited by the internal
> resistance of the alternator windings, not the internal resistance of
> the battery. Any motorcycle starting battery can draw far more charging
> current than the motorcycle can produce. In fact, a motorcycle starting
> battery can draw more charging current than most car alternators can
> produce. Regardless of whether the motorcycle battery is rated for a
> lowly 150 amps of starting current or 450 amps, it's still more than the
> 90 to 120 amps a car alternator is limited to.
>

So he's talking bollocks, is he?



--
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
From: No Spam on
I tried to cancel my previous reply to this post... here is something
a little more concise.

"." <an.gleann.mor(a)gmail.com> wrote in
news:a1a87efb-06b2-4801-9540-0135e7e928c8(a)11g2000prw.googlegroups.com:

> ...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