Re: GPZ500 No Spark!

Ted Mittelstaedt wrote:
"FB" <flying_booger@xxxxxxxxx> wrote in message
news:1148317618.114777.204800@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

oldgeezer wrote:

In the parallel situation, if the bike battery it is 'empty' and so old
that it cannot hold much charge, it will drain your car battery fast.
Your car battery will output many amps to your bike battery trying
to charge it.

No, that's not true at all. If you jumper your car battery to the
motorcyle battery and the car engine isn't running, the car battery
voltage will be somewhere between 11.9 volts (dead battery) and 12.8
volts (fully charged *resting* battery).

So, a "dead" motorcycle battery will only get about 0.9 volts from a
fully charged resting car battery and the charge rate (if any charge
takes place) will be at a very low rate.

<snip>
Correct. Unless the bike batt is totally shorted (which is
very unlikely). To be sure: unhook the bike batt first.
Remember: MonkeyBoy tried to find out why sparks were weak.
Hooking up a fresh battery could tell: bike battery is
not good (either empty/shorted/sulphated, which would
be the next step to determine), or --if sparks still were weak--
problem is somewhere else.

A car starter pulls many hundreds of amps from a car battery during
starting and that does not warp car battery plates. If a motorcycle
battery pulled this much power off a car battery it would explode
because it could not dissapate the heat fast enough.

Correct. This is the case when the bike batt is sulphated.
Remember that a bike battery has an internal resistance
that is about 6 times the internal resistance of a car batt
and when it is sulphated it is even higher than that, so
many amps will dissipate much energy inside that
bike battery.
To be sure: unhook the bike battery first.

You could end up with warped plates in the car battery because
of the high current it then puts out.

Plate warping and lead shedding occur with a battery is charged at too
high a rate. That would never happen to a resting car battery while
hooked across a dead motorcycle battery.
True if bike battery has not enough charge but is internally okay.
I stand corrected here, warping is unlikely.

The reason for running the car's engine is to use the excess voltage to
charge the
battery in the *assisted vehicle*, as a fully charged resting battery
would take about 24 hours to equalize its charge with the dead battery
*if anything happened at all.
I made the wrong assumption.

Really dead batteries need to be *shocked* into life with higher
voltage than you imagine. Refer to what I said about variable voltage
charging.

You cannot "shock" a "really dead" battery into life. If a wet cell battery
is
really dead - which is defined as it won't take a charge anymore and
will not provide power - the plates have sulphated and are ruined.
Yup.

There are some hairbrained schemes around to supposedly "unsulphate"
lead acid battery plates. Most of these are -highly- dangerous ..
<snip>
A battery is cheap compared to trying to clean up a motorcycle that has
been showered with battery acid. And even if it works, what you end up
with is a motorcycle battery that has lost -significant- capacity, it may
be alive enough to start the engine if the engine starts easily on the
first couple revolutions, but if it gets cold or hot it will probably go
dead.
Correct. Not worth to try it. I hate to think about acid splatting
all over the area, or over myself.

Check how fast the bike battery starts bubbling when you have it
on the charger. If it bubbles within a few minutes, it cannot hold
charge and you have to buy a new one.

The only reason I can imagine for a battery to begin bubbling
immediately would be if there were shorted plates.

If a battery is fully charged and it starts bubbling it's being overcharged,
which happens if the voltage regulator is screwed up.
Yes, and it will be overcharged soon when it is sulphated or has
shorted plates..
This is plain experience. I never gave this much thought. Begin
with a battery that reads 12.1 Volts, Hook it up to a charger. Soon
bubbling to me means 'battery defect, go buy a new one'.

There is a lot of misinformation about what can happen if you jump
start a motorcycle using a car battery and nobody else seems to realize
what will happen except me.

I've heard this one before.
Unlike FB I do not know everything. I've been maintaining bikes
for over 40 years now, before that helped my father in his
bike repair shop and I am still learning.

I will say this over and over and over.

The danger is to the motorcycle's alternator and the rectifier diodes.
Since motorcycles do not have a generator switch like an airplane, the
alternator is connected to the battery through the rectifier regulator
at all times.
I cannot remember any generator switch in the F104G, but it was
1968 when I started such a crate on the run-up for the last time,
but FB is correct, the generator of the bike is connected at all
times..

If you jump start the motorcycle with a car battery that is, say,
half-charged, the motorcycle alternator will then try to charge the car
battery *and* the dead motorcycle battery.

This could lead to a damged alternator stator or blown diodes.
See? I am still learning. Never thought about this possibility. But I
also never jump started a bike too. Never needed to, because it
was always obvious that the battery was defect.

So, the absolute best way to solve the dead motorcycle battery problem
is to charge the motorcycle battery, do the capacity test you described
with a headlight across the battery terminals, and, if the battery
fails that test, replace the battery with a fully charged new battery
and go from there.


Frankly if the battery has been let set for 6 months without a trickle
charger
it's sulphated, and has lost significant capacity, just replace the damn
thing.
Which is exactly what MonkeyBoy should do.

Some weeks ago I helped on my neighbors daughter's moped.
It had been left alone during winter. Battery sulphated.
Because it was monday and all motorbike shops closed,
from the telephone diary I picked an address that sells
'motor electronics'. They came up with the same Yuasa I have
in my bike. I normally pay around 50 Euros for them.
The motor-electronics shop charged 35 Euros.
So MonkeyBoy should shop around.

Rob.

.

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