The horror stories usually involved a running "donor battery & charging system" sending transients down to unprotected motorcycle charging system (the battery normally acts like a huge capacitor (electrical charge storage).
When it battery is fully discharged, it can have shorted cells (low resistance) or if just discharged only, (high resistance) that a charger has to "force" it's way through, but with nothing controlling voltage rise, transients from the donor vehicle will pass unabated into the low capacity "cooking" unprotected motorcycle charging ckt...
If you must jump start, do not have the donor car/truck running...only the fully charged battery and good jumper clamps and cables, connect, "waggle" the connections so they are good and tight, wait a minute or more before attempting to start the bike. If unable to start and you see your HD headlamp dim to 1/2 or go out when you hit the start button, it will not start (9V left for EFI, ICM/ECM...your battery is toast...and you do not want to run the bike like that. Forcing the stator/charging ckt to provide all the power for the systems and feeding the internally shorted battery is inviting trouble...
When it battery is fully discharged, it can have shorted cells (low resistance) or if just discharged only, (high resistance) that a charger has to "force" it's way through, but with nothing controlling voltage rise, transients from the donor vehicle will pass unabated into the low capacity "cooking" unprotected motorcycle charging ckt...
If you must jump start, do not have the donor car/truck running...only the fully charged battery and good jumper clamps and cables, connect, "waggle" the connections so they are good and tight, wait a minute or more before attempting to start the bike. If unable to start and you see your HD headlamp dim to 1/2 or go out when you hit the start button, it will not start (9V left for EFI, ICM/ECM...your battery is toast...and you do not want to run the bike like that. Forcing the stator/charging ckt to provide all the power for the systems and feeding the internally shorted battery is inviting trouble...
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