Don't jump start a bike off a car battery

[likearock4x4]

Originally Posted by 78_KZ750_Cafe

Whoa there tawd, where did you get your electrical engineering degree? Amperage is definately the main issue in jump starting a bike with a car system. The amps are the maximum flux of power, sort of like how fast water flows through a pipe. voltage is the electrical potential - the amount of water in the tank. running higher amperage through a system than what its designed for will eff it up pretty bad - push a lot more water through a pipe than the pipe can handle without bursting. that said, you CAN jump a bike with a car battery, just don't have the car running. The batteries current is limited but the alternators is much higher. you don't want the current from your alternator frying the circuits in your bike.

ummmmm.... the push is the voltage. the only way to push more water (current) is to increase the pressure or push (voltage) or to lower the resistance (increase the size of the pipe). If, with the same system, you don't increase the voltage, you won't increase the current.

I believe that the amperage rating on a system is the amount of amperage the system is capable of, not necessarily how much it pushes throught the system. (But, since I'm not an auto mechanic, I'm not sure.)

[Scruffy]

I jump start both 6 and 12 volt bikes off of car 12 volt batteries all the time. Yes, you CAN jump a 6 volt with a 12 volt, 6 volt wiring is twice as thick as 12 volt wiring (6 volt systems push/draw more amps). Just do so quickly. Have only ever popped one battery, and that was jumping a 12 volt with a 24 volt rig.
-Scruffy

[zedx11]

so, has anyone looked in their owners manual? or am I the only one that has one?

[Frankt07]

i havent looked. but thats cuz im a stubborn cuban redneck that knows it all

[nwujames]

last time i read my manual i was on the train - got so into it i missed my stop and got stuck on the express all the way in evanston. 1 hour later, i was late for dinner and knew a lot more about my bike

[78_KZ750_Cafe]

okay, so my metaphor didn't work out, I didn't want to go into a diatribe about Ohm's law, I'm lazy okay.

[CowboyBob]

It is definately the amperage at issue!!!!! And it will pop stuff real good...1/2 an amp can kill ya!!!! A static electricity or ESD in PC terms is 10K volts but has no amps....it hurts PC circuits due to they're extremely low volt requirements. The fuses in your car are rated for amps as are the ones in your bike...why...to [protect from too much amperage!!! If a charge of more amps than the circuit is rated for flows through it the fuse pops...if there is no fuse the wires get hot and melt their casing! I screwed up trying to hardwire a radar detector into a mustang I used to own and had to pull melting wires out from under the dash!!!! As far as voltage is concerned DC is worse to get shocked by than AC! If the car is running when you charge it you can definately fry stuff even if it is hooked up correctly as your alternator puts out about 45 amps or more depending on the vehicle you are jumping your bike with. My last Chevy pickup had an 85amp alternator.

[damarble]

^^^ QFT. It's the amps that get you every time.

[CowboyBob]

The reason you start the car whenjumping another car is to bost the available amperage...batteries are rated in CCA...Cold Cranking Amps! Your battery charger that you may use to trickle charge a battery or it may even have a jump start capability is rated by amps. Trickle chargers are low amp, the starting boost is generally 200 amps. As Scruffy said you can use 12 to 6 volt for jumping.

[Scruffy]

Bikes have owner's manuals? When did they start doing that?
-Scruffy

[CTRider]

Originally Posted by 78_KZ750_Cafe

okay, so my metaphor didn't work out, I didn't want to go into a diatribe about Ohm's law, I'm lazy okay.

It was sort of right. Instead it probably should have been:

Voltage: The amount of water running through the pipe. The amount can go up and down within certain limits, can regulated to a normal flow. In our example, the flow is constant.

Amps: The nozzle at the end which determines how much pressure will be released (the alternator). The flow of the water through the pipe is the same, but we can squeeze it (or boost it) as it comes out to make a more powerful blast. Enough to knock you on your butt, if desired.

Ohms: That is generated by the pipe itself. The pipe only lets so much water go through. A certain amount of water is needed based on pipe size in order to have a usuable amount of water at the end of the line. Too much water (current), and the pipe bursts. Too little, and the water will only dribble out.

However, even with a small amount of water flow (current) we can generate more pressure (amps) by using a more constricting nozzle.

[MotorBone]

Ohm's Law

Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.

( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) amperes or amps.

( E ) Voltage is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.

( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.

( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts.

[likearock4x4]

Originally Posted by MotorBone

Ohm's Law

Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.

( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) amperes or amps.

( E ) Voltage is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.

( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.

( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts.

Right on brother!!! You got it!!! To compare electrical with physical systems:

I = current flow in electrical systems, water flow in physical systems

E = voltage in electrical systems, and the pressure that is exerted on the water in physical systems

R = resistance to the flow in electrical and physical systems (i.e. the size of the pipe or how long the pipe is)

[kwakbloke]

Surely it doesn't matter what is being pushed out by the generator, it's the load at the end that draws the power? It's no different to using a Dodge Viper to jumpstart a Nissan Micra, surely?

12 volts is 12 volts no matter where it comes from.

[cARLCROM]

Kinda so's we all understand and agree on a few easy points,...

Voltage is ........a cool laid back Potential...... (pusher thing)
Amperage is .....actual hot stuff moving ...(hot, welds things)
Resistance .... ..fights against the "hot stuff" happening

Ergo, a dead (depleted) battery has low, or no internal resistance and can't stop the hot stuff from happening....repeat, ....ANY dead battery (no resistance), connected to good strong potential will allow the Hot stuff to happen, quickly and excessively! (An added bonus is hydrogen can be present (Hindenberg) to help in the explosion)

The hot stuff can weld and fuse all parts of the dead system. Yep, the electrical shock may be transmitted to any and everything on your bike....

It's much smarter to disconnect the dead battery from your system... and charge it "gently," then reconnect it for starting. Use a "limited" amperage source for a 24 hour charge/charging......
Addemdem: Starting off of a running automobile is worse. Can be very, very bad! The 12 volt charging system is set to run at 14.7 volts potential...

Boy can I jabber...LOL ....... I hope it helps you

Carl
KL-259 Super Sherpa
F-650GSA

[danallen636]

Originally Posted by tawd

You cant burn anything up by jumpstarting a motorcycle with a 12v system from a car. The car having a higher amperage charging system will NOT hurt anything. Voltage is whats important, not amperage.

actually amps do matter if you run to many amps though a smallish wire it can very easily fry it. i only know this because i used to install car audio systems

[175mph]

Jump started my bike dozen of time using car battery both ways with the car engine on and off... no problem at all, and she is still running....

[kwagner88]

As an electrical engineer, I can tell you with absolute certainty that it doesn't' matter one bit what the amp difference is between the two batteries. When you hook up jumpers, they are in PARALLEL which means that the only thing of importance is the voltage. I'm not trying to imply that strange things can't happen (kick-back is one of those strange occurances), but if they do. . .your battery was defective anyway.

[mysticalstorm]

ive jumped both bikes with my truck in the past and every time ive had to start the truck to get the bike to crank fast enough to start .. the kawi was when i was haven the carb troubles and it was a hard start and the honda was the first start after getting it .. both times the bike cranked but wouldnt start with the truck off and as soon as we started it .. presto the bikes started

[95ZX600R]

Breifly went throught this thread, not entirely sure if this has been said but:

A cars electrical system, or any electrical system, will only output as much amperage as is being drawn upon. That is to say, just because you're car has a 110amp alternator - it's usually not putting out anywhere near that. As load increases, alternator output increases as it needs to.

Cold cranking amps is the batterys rating of the max amps it will pump out from a cold start, without alternator assistance. Once your car is running it is no longer pulling power from the battery, it's running completely off the alternator. CCA are needed as a buffer to spin the starter until the crank starts spinning and thus the alternator.