Will it run without a battery?

[earlfor]

It isnt the battery capacity that is the problem. Of course you can jump start your bike from a 5000 amp hour ships battery if you want to. It makes no difference. The "doner" vehicle should not be running. The problem comes from two charging systems trying simultaneously to regulate one battery. The weaker system will be destroyed. In this case, that means the bike electricals. I realize in theory this doesnt happen, however in the case of bikes, I most certainly can.

I've replaced many stators and R/R for people that didnt believe it was true. LOL

A "legend" it is NOT.

In any event, with most car batteries having a cranking capacity of 700 to 1000 amps or more, there is NO reason at all for the car to be running when jump starting a motorcycle.


Earl

i am not sure where the urban legend of killing the bikes charging system when jumpstarting from a running car came from but its just that.
i have jumpstarted many bikes including suzuki gs from a running van with a 300a leece neville truck alternator.
never did any damage.the way most folks damage things is reverse polarity.
and the bike doesnt care if it starts from a 14 ah yb14a2 or a 300ah 8d semi battery.
just remember you can crank the starter long enough to overheat it on a larger battery or a jumpstarter.the relatively small battery in a bike limits this.
i hope this puts this often heard misinformation to rest onece and for all.

 

[snakebite]

never heard of such a thing
of course the cars system will likely hold the voltage at the regulator setpoint during the jump. the bikes regulator will sense voltage at the similar setpoint and simply not deliver anything not needed to maintain 13.8-14.2 v dc.
you have likely replaced lots of gs stator/rr simply because lots of em fail.
not due to jumpstarting.
except for idiots who cant tell black from red or + -

The problem comes from two charging systems trying simultaneously to regulate one battery. The weaker system will be destroyed. In this case, that means the bike electricals. I realize in theory this doesnt happen, however in the case of bikes, I most certainly can.

A "legend" it is NOT.

In any event, with most car batteries having a cranking capacity of 700 to 1000 amps or more, there is NO reason at all for the car to be running when jump starting a motorcycle.


Earl

i am not sure where the urban legend of killing the bikes charging system when jumpstarting from a running car came from but its just that.
i have jumpstarted many bikes including suzuki gs from a running van with a 300a leece neville truck alternator.
never did any damage.the way most folks damage things is reverse polarity.
and the bike doesnt care if it starts from a 14 ah yb14a2 or a 300ah 8d semi battery.
just remember you can crank the starter long enough to overheat it on a larger battery or a jumpstarter.the relatively small battery in a bike limits this.
i hope this puts this often heard misinformation to rest onece and for all.

 

[earlfor]

I wonder why some auto manufacturers specify that if jump starting their cars, the vehicle providing the jumpstart should not be running.

Its your money, so its not a difficulty for me.

Earl

never heard of such a thing
of course the cars system will likely hold the voltage at the regulator setpoint during the jump. the bikes regulator will sense voltage at the similar setpoint and simply not deliver anything not needed to maintain 13.8-14.2 v dc.
you have likely replaced lots of gs stator/rr simply because lots of em fail.
not due to jumpstarting.
except for idiots who cant tell black from red or + -

The problem comes from two charging systems trying simultaneously to regulate one battery. The weaker system will be destroyed. In this case, that means the bike electricals. I realize in theory this doesnt happen, however in the case of bikes, I most certainly can.

A "legend" it is NOT.

In any event, with most car batteries having a cranking capacity of 700 to 1000 amps or more, there is NO reason at all for the car to be running when jump starting a motorcycle.


Earl

i am not sure where the urban legend of killing the bikes charging system when jumpstarting from a running car came from but its just that.
i have jumpstarted many bikes including suzuki gs from a running van with a 300a leece neville truck alternator.
never did any damage.the way most folks damage things is reverse polarity.
and the bike doesnt care if it starts from a 14 ah yb14a2 or a 300ah 8d semi battery.
just remember you can crank the starter long enough to overheat it on a larger battery or a jumpstarter.the relatively small battery in a bike limits this.
i hope this puts this often heard misinformation to rest onece and for all.

 

[redliner1973]

I have also seen a NUMBER of occasions where a perfectly working GS charging system gets blown out after someone leaves the ACC on or something to run down the battery and gets it jumped from a running auto.

the bikes regulator will sense voltage at the similar setpoint and simply not deliver anything not needed to maintain 13.8-14.2 v dc.

true, but the problem is so much current is being pushed back into the regulator and stator. The regulator diodes short, power goes directly to the stator, and with no where else to go, the stator heats up and burns out. each component is fighting for the battery, and the auto, with its much-higher charging amperage, usually wins. The reason this does not happen with teh engine NOT running, is no matter how big the battery, the battery voltage is lower than the motorcycles charging current. The current therefore flows out to the MC and the jumper battery.

While this may not have happened the last time you jumped a vehicle, eventually, it will happen, not might, but when. And contrary to what you might think, most all of us here that have had a stator blow out from jumping from a running auto, were competent enough to attach the right leads to the right posts....

 

[snakebite]

look at the schematic and tell me how you can force current back thru the scr's used in a rr.
think of them as switchable diodes.
they conduct one way.
unless you exceed their prv.
not gonna happen jumping from a running car.
shindengen has used the same rr design since the 70's. they supply the lions share of rr for jap bikes.
i have seen a few hitachi too.
if this damage was gonna happen it would have meant a pile of dead rr here.
from all jap bikes.
not just gs.