Jump starting a dead battery

Albrecht via MotorcycleKB.com schreef:

So far, so good.

What makes you think that *all* RRs have a 100 Ohm/1000 Ohm inside?

Here you go a bit astray. One phase shunting was done in the
seventies.

The 'silicon control rectifier' is named Thyristor.
Zener diodes are used reverse mounted (blocking) and start conducting
in the 'wrong way' when the voltage across them reaches the specific
threshold they are designed for..
Thyristors do almost the same, but start reverse conducting only
when a trigger signal is given to them (zeners have two leads,
thyristors have three leads, one being the trigger connector).
The zeners each trigger a Thyristor, and can be very small
because the trigger signal is usually in the milliAmps range.

Above you describe my electric disaster Suzi GT250 (1970).
That had a permanent magnet three phase generator of which
only a single phase was shunted, so it kept on puttting Amps
in my battery, even when the battery was full.
Only one leg 'shunted' and the other legs kept on pumping
electrons. Not so many as before, but still too much to handle
for the battery. Yes, half of the normal output. The diagram was
different and I cannot scribble that here, but effectively they
shunted 1.5 of the three windings, by changing a full
bridge rectifier into a half-bridge rectifier.

My later Kawa and Honda (around 1985) all had a three phase
permanent magnet generator, and all three phases were
shunt to ground when the voltage got above threshold.
The voltage sensor was a seperate wire, basically monitoring
the battery voltage.

It is important to realize that the center of the generator
in a star configuration (where the three coils are connected
to eachother) is NOT connected to ground. It electrically
'floats'.
It means that the 12V (and over) is generated by two coils
in series. Over and over again.

The regulator thyristors carry the full load of the generator
when the voltage gets too high, shorting two coils at a time,
(two thyristors in series, both conducting) no matter if the
Voltage is positive or negative.
Thyristors work like switches. When 'open' they behave
as diode (current one way only) but when 'closed' they
behave as a contact, and current can flow in both directions.
When closed, then no output from the generator
(momentarily) until the trigger signal (too high a
voltage) is withdrawn AND the current 'goes through zero'.
The latter is when the voltage reverses, which will happen
at an AC generator.
Was the generator a DC thing (battery) then even
when the trigger signal was withdrawn the thyristor
would continue conducting until the battery is flat.

This is too much generalizing. There could be motorcycle
RR's that can you can mount in a car without a problem.

Returning to the original situation: jump starting with
a car.
The RR (motorcycle) wont shunt the car because the
thyristors are connected to the car via the reverse(!)
rectifier diodes that block current towards the motorcycle
regulator.

I think that is exactly what I said above.

Most of what you wrote is correct. Are you p*issed off now?

Rob.

 

This is my experience in a related issue. I had trouble with an AGM
battery (MK brand) refusing to hold a charge over a (0 deg F) cold
night.
In my case, the bike in question is a 2004 Kawasaki Vulcan 1600
cruiser. I did successfully jump-start off my Chevy K1500 @ truck
engine running, and judging by the sluggish rotation rate of the bike
starter I would say that I was DEFINITELY not over-juicing the bike
and its battery. This was in spite of an AWG #4 jumper cable.
I had gotten the MK battery "on my own", and the failure caused
me to replace it with the OEM make, by Sumitomo. The difference:
the Sumitomo STZ16-BS is "flooded technology", meaning classic
liquid electrolyte and not gel or AGM (absorptive glass matting).
I reckon that thermal contraction could have ripped some of the
AGM off the sponge anode in the MK, but obviously this cannot
happen with liquid electrolyte. Incidentally, the Sumitomo battery
has hydrogen storage bladders, etc, so that it truly functions as
"maintenance free".
Hope that helps!

Raymond A. Byrnes, Jr.
B.S.E.E., M.S., Ph.D.

 

The amusing thing about this is that it implies a certain stalker-like
behaviour on B12's part.