Re: GPZ500 No Spark!


"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.

When charging a dead motorcycle battery from a variable voltage
charger, you want to crank the voltage up to about 20 to 25 volts to
see if *anything* happens. If you see a charge on the ammeter, reduce
the voltage to about 15 or 16 volts to get the
*slow charge* rate on the sticker on top of the battery.


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.

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.

When people do this parallel setup with cars, which is the
normal way it is done, then the guy with the good car always
starts his engine first and runs it a high revs, so that his generator
helps his own battery.

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.

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.

There are some hairbrained schemes around to supposedly "unsulphate"
lead acid battery plates. Most of these are -highly- dangerous if they
involve any sort of fast-charging of the battery and you would certainly
remove the battery from the motorcycle and set it OUTSIDE on a
concrete slab, with protection erected around it, in case it exploded.
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.

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.

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.

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.

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.


The most I've seen a half-charged car battery draw from a battery charger
with an ammeter on it is about 20amps. The motorcycle headlight and all
lights on the bike probably draw this amount. And I think such a scenario
is speculative anyway, how many people are going to have a half-charged
car battery in a car?

Much more dangerous is that most motorcycles do not have handy charging
posts and I've seen people pull all kinds of stunts with screwdrivers and
such to try to charge a motorcycle battery off jumper cables. If you short
across the battery terminals even for a second, you will almost certainly
blow
diodes.

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.

Ted


.

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