Jump Starting
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Joined: Jul 2009
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From: Straight Jacket Memories and Sedative Highs
So why do you think a jump pack is ok, but not jump starting?
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Joined: Aug 2008
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on an alternator, the output is variable and controllable. the stator has residual magnetism and will produce a startup field into the field coils. if you remember the older cars, the charge light or gauge did not always indicated charge until engine speed came up.
the regulator would send battery voltage to the stator and the increased current increased the magnetic flux or strength which induced more current in the field coils so the alternator can vary its charge rate.
the BIG issue with disconnecting the alternator is that there is a large voltage spike produced and this spike could blow out the rectified diodes, the older mechanical regulator did better but still the influx could damage other systems like radios and such, but back then not much of that.
the pmg is fixed. its output is largely fixed to speed. since the pmg is very low at idle speeds, a disconnect usually does no harm but the potential is still there. so what happens to the excess when not needed at speed since there is no field forcing???
there are many style regulators out there and the newer switch mode is the latest and greatest. the regulator basically operated like a very fast switch that holds a set value usually controlled by a zener diode. there is a protection circuit that kicks in when the pmg voltage climbs too high and it shunts current to ground. this circuit usually is idle under normal riding conditions as demand keeps things in check since it was engineered to do so.
the newer switch mode is $$$$$ but is more efficient, most all newer electronics use it, gone the heavy transformers. it has a timer circuit that controls when it turns on according to demand. it can turn on for full wave form or part of the wave form which then controls output.
the regulator would send battery voltage to the stator and the increased current increased the magnetic flux or strength which induced more current in the field coils so the alternator can vary its charge rate.
the BIG issue with disconnecting the alternator is that there is a large voltage spike produced and this spike could blow out the rectified diodes, the older mechanical regulator did better but still the influx could damage other systems like radios and such, but back then not much of that.
the pmg is fixed. its output is largely fixed to speed. since the pmg is very low at idle speeds, a disconnect usually does no harm but the potential is still there. so what happens to the excess when not needed at speed since there is no field forcing???
there are many style regulators out there and the newer switch mode is the latest and greatest. the regulator basically operated like a very fast switch that holds a set value usually controlled by a zener diode. there is a protection circuit that kicks in when the pmg voltage climbs too high and it shunts current to ground. this circuit usually is idle under normal riding conditions as demand keeps things in check since it was engineered to do so.
the newer switch mode is $$$$$ but is more efficient, most all newer electronics use it, gone the heavy transformers. it has a timer circuit that controls when it turns on according to demand. it can turn on for full wave form or part of the wave form which then controls output.
Banned
Joined: Jul 2009
Posts: 7,406
Likes: 834
From: Straight Jacket Memories and Sedative Highs
Jump packs are lighter and quicker than a 2nd battery.
some people will add 2nd battery to sxs with diode so it is only used for starting. Not sure if they do that in trucks.
some people will add 2nd battery to sxs with diode so it is only used for starting. Not sure if they do that in trucks.
Outstanding HDF Member
Joined: Feb 2015
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From: Arkansas
Personally I figure jump starting is ok if the battery is good but the ignition switch was left on, best way to do it is positive on battery and negative on a ground, bad batteries will tear up the Voltage Regulator before they take out the stator, bad VR usually takes out the stator. I have a couple of the jumper packs, they work well.
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