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Settle an aurguement
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My battery died the other day and my neighbor asked why I didn't get a jump
instead of walking home to get the trailer and tow it home.
I said the general consensus is that jumping a motorcycle from a car is a
"bad idea". Now he is an electriction and said 12volts is 12 volts and
there will be no problem.
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First, just because he is an electrician does not mean he knows about
automotive charging systems. He probably specializes in some field. What
is his specialty in the trade?
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I seem to recall a discussion about this awhile back and some point was made
about the load put on the stator or some other component.
Can anyone help me out here? I hate it when he pulls the "I'm an
electriction, therefore I know what I am talking about" attitude.
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Get a degree in electrical engineering and you can own him.
He's right-- it won't hurt anything, so long as you don't start the car, the
car's battery won't do anything bad to your bike. However, if the car's
alternator is spinning and putting out a lot of charging current the voltage
*can* overwhelm your bike's regulator.
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The load i.e. bike's starter motor, electronic gizmos etc. determine
the level of current drawn from the nurse source whether or not its
motor is running. To the bike a 12 Vdc source is a 12 Vdc source. I
seriously doubt that the 13 or 14 Volts the car's system generates with
the alternator running is any higher than when the bike's own
alternator is running. Even if it is, the voltage is certainly not
outside the range of the bike regulator's ability to handle it.
The biggest thing to watch for is that the batteries are of equal
voltage. Some bikes use batteries that operate at voltages lower than
12 Vdc. Hooking up to such would be a badddd idea.
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Jumping off a car battery is fine, IF the car is not running.
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And even if it IS running.
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I disagree. If the car battery is not fully charged, after the bike
starts, it will be charging both the flat mc battery, as well as the
partially charged car battery. Since the charging system is going to be
overtaxed simply by charging the flat mc battery (charging systems are
designed to keep the battery at full charge, not to re-charge from a deep
discharge), adding a second load to the system is going to be double
jeopardy.
It's really not even a good idea to push-start a flat battery, the best
idea is to keep the batteries charged up in the garage. When the battery
gets deeply discharged to the point where it will not start the bike, its
life has been severely shortened anyway, so why subject the charging system
to the abuse of re-charging a battery that is on its way to being useless?
Brian did the right thing. Take the flat battery home and use a charger.
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He may be forgetting (or not understanding) that a car's alternator can
dump a significant amount of AC onto the DC system which a car's battery
will mostly shunt. However, I think that most older motorcycle
regulator/rectifier units aren't designed to withstand any amount of
reverse voltage over maybe 15 ~ 20V so smacking them with a few tens of
volts of AC will cause them to be damaged in short order especially since
they may not have reverse polarity protection built into the units.
Jumping a bike with a 12V system from a non-running car with a 12V system
should not cause a problem unless the leads become reversed.
- Nate >>
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he sounds like a real Joule. But let's not get all amped over this
question, even if it is downright re-volting. Ohm my, let's see, I seem
to remember a discussion currently about leaving the motor OFF while
jumping a bike, otherwise you'll blow a fuse, really.
Shocking isn't it?
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There is good ground in Watt you say, Ready Kilo-Watt would not be pleased
in such treatment of the cycle. The electromotive potential to damage the
rectifier regulator is great. Electrician's attitude has too much
resistance.
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I've done it.
I just didn't have the car running.
But then you have a Honda stator.
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Anyone who prefaces his opinion with "I'm , I know what I'm talking
about," is likely afraid his opinion cannot rest on its own merits.
And, yeah, "Settle an argument?" Ha. As if. See what you started? :-)
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he's right.... i usually don't start the vehicles engines, but jumping from
a vehicle is perfectly safe and fine...
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I used to have a bike which needed jumped regularly while I tried to figure
out why the battery wouldn't hold much of a charge. I had a spare car
battery laying around the garage and I would jumper cable from that battery
to the bike battery and fire it up that way all the time. 12V being 12V
seemed to work in that situation.
I would use a car battery actually IN the car to do it again, but I wouldn't
have the car running while I did it I suppose. But 12V is 12V works for me
as long as the cars charging system isn't trying to fire the 12V's at the
same time.
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Shouldn't be an issue. As long as the voltages are the same.
Think of a 15amp alternator as a 15 amp wall outlet. Think of the
bike as an 8 amp load. This leaves 7 amps not drawn on the alternator.
The alternator only supplies the current demanded by said load up to
a maximum value.
Also the cars battery acts as a huge current reserve pool. The alternators
output probably doesn't even change much jumping a bike.
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