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  Topic Review (Newest First)
09-22-2019 03:41 PM
Harkon
Quote:
Originally Posted by Blaine C View Post
With car running its more amps that the bike system was designed for...Can also destroy the ECU....(Seen it happen more than once)
The amps won't hurt the ECU. The ECU is damaged by high voltage and transients. Volts are like line pressure, amps are like how much you open the valve. All 12V systems have the same (approximately) line pressure. A tail light only opens the valve a little bit, a starter motor opens the valve a lot. At some point you open enough valves that the pressure starts to drop. A big battery has greater pressure or volume reserve than a smaller battery. Think water pumps, 2 pumps, both can deliver 100psi, but one pump can deliver 10gal/minute, and the other 50gal/minute, but both peak at 100psi. Neither will blow out a 100psi rated hose, but one can supply 5 times as much water as the other. In electricity, amps are like gal/min, and volts are like PSI. A battery is just an electron pump.


Like with water and hose, sparking, and arcing is like rapidly opening and closing a valve. This can, and will cause surges and pressure (voltage) spikes. Depending on the size of the pump and the amount and rate of open/close, surges can become significant. This is why whenever you jump vehicles, even car to car, both cars should be turned off at time of jumper cable connection, to avoid damage to sensitive electronics. It's not just bikes, many have damaged their vehicles automation system with sloppy boosting practice.


I want to be clear though, electricity and hydraulics are not all the same and only share similarities, and the above is illustrative and should be viewed as such. In order to completely understand electricity, one must come to understand the very properties of electrons. A vehicle electrical system is equal parts chemistry and physics.
09-22-2019 11:47 AM
enduro
Quote:
Originally Posted by Blaine C View Post
With car running its more amps that the bike system was designed for...Can also destroy the ECU....(Seen it happen more than once)
At a set voltage you can't force excess electricity into something, the load determines the current. Your bike battery alone is capable of over 100A. A car/truck works on a 12V system same as the bike, both systems are charged from 14.2-14.4V charging systems. Standard alternators output less than 100A, a high output alternator is capable of 100-150A output and so is your bike battery. If you charge off a non-running vehicle or just a bare auto battery it might be capable of providing over 1000A from a full size battery. Doesn't matter as the bike (the load) determines how much current it will use. You could have a dual battery system capable of over 2000A and it still isn't going to hurt the bike. You can't force excess current thru a load while holding the voltage constant, electrical laws prevent it.

At home you have a 200A service with multiple 20A receptacles, plug in a .004A (.5W) night light and it doesn't blow because 20A is available. It uses what it needs and you can't force more through it.
A running diesel truck with dual batteries can supply over 2000A from the batteries and additionally 150A from the alternator. Nothing electrical is turned on, you open the door and the little inside cab light comes on. It is not damaged even though over 2150A are available, because the voltage is held at 14V and the current (load) is determined by the light itself, constant voltage and constant load equals constant current.
09-22-2019 10:08 AM
Donnie Downer I was expecting something completely different

https://youtu.be/7ax-9yJs78Y
09-22-2019 09:22 AM
TennX AS mentioned be careful when jumping anything...as a young man I went to help a stranger ....battery blew up in my face...only thing that saved my eyes that time were my sunglasses.....
09-22-2019 08:46 AM
Blaine C
Quote:
Originally Posted by Harkon View Post
Right, they are both 12Vdc lead acid systems so there is nothing that could possibly damage one or the other. There is an established process by which one should connect and disconnect to minimize the possibility of injury.


I the case the car is running and the bike starts, you now have two charging systems of significantly different capacities possibly creating a conflict. There is a possibility the rectifier/regulator of the bike might be damaged if the jumper cables are not removed quickly upon starting. As the car battery has significant capacity to start a bike, and restart the car afterwards, it makes sense to me to take the extra precaution of leaving the car ignition off. Only as a precaution mind you.
With car running its more amps that the bike system was designed for...Can also destroy the ECU....(Seen it happen more than once)
09-21-2019 11:19 PM
skeeter69392 yup with the car off
jumped bikes,,atv,,lawnmowers no issues
09-21-2019 05:21 PM
Harkon
Quote:
Originally Posted by Mowoc View Post
I found this for those that are curious:

https://advrider.com/f/threads/will-...-system.66214/

Apparently its fine - the issue is not the over charging or even the running/non running. Its the spark from the dead/low battery igniting a hydrogen explosion and royally screwing your day up by throwing acid all over you.
Right, they are both 12Vdc lead acid systems so there is nothing that could possibly damage one or the other. There is an established process by which one should connect and disconnect to minimize the possibility of injury.


I the case the car is running and the bike starts, you now have two charging systems of significantly different capacities possibly creating a conflict. There is a possibility the rectifier/regulator of the bike might be damaged if the jumper cables are not removed quickly upon starting. As the car battery has significant capacity to start a bike, and restart the car afterwards, it makes sense to me to take the extra precaution of leaving the car ignition off. Only as a precaution mind you.
09-20-2019 06:53 PM
Mowoc I found this for those that are curious:

https://advrider.com/f/threads/will-...-system.66214/

Apparently its fine - the issue is not the over charging or even the running/non running. Its the spark from the dead/low battery igniting a hydrogen explosion and royally screwing your day up by throwing acid all over you.
09-20-2019 06:16 PM
Mowoc agreed.

My question really was what can be damaged. If its just the battery - fine. I can deal with that. Is there something else (solenoid, or switch) that can have issues?

It seems logical that the batter might have issues if there is a power surge since it is the ingress for the jump.

BTW, the guy just started the car - I didn't even see him jump in the car. It was literally as I was keying the bike and starting it. I got home and I am safe so that part is all good.
09-20-2019 05:46 PM
Harkon I would not leave the car running while trying to start a bike. If the car is not running there really isn't anything that can be damaged on the bike.
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