Jump Bike with Car Battery?

Question

Why do people claim that you should never give your bike a jump with your car battery ,I would like to know the reason

Answer 1

george b and Firecracker gave accurate answers, I've been using car batteries to jump start motorcycles for ions without a problem. Even if a car battery puts out 10,000 amps, the amperage has to go through the "main fuse" before it gets to the ignition switch and touch any electrical part of the bike. Main fuses on bikes are usually 30 amps. The fuse would blow before any damage is done. As for fuel injected bikes, the computers are very sensitive. To much amperage would fry them. Jap bikes have a special feature to prevent someone from hot wiring the bike (by-pass the ignition switch). Inside the ignition switch is a resistor which steps down the amperage to less than 5 amps. If to much amperage were to be sent to the computer, it wouldn't operate. So the resistor is an added saftey feature if you were to remove the main fuse and connecct the terminals directly.

Answer 2

It's the amperage, but not because it's bad for the bike. You could have a million amp 12 volt source and the bike wouldn't care. The bad thing is that, if your bike battery is dead, putting a car battery to it can send a lot of charging current into the bike battery. They're not made to take too much charge. Just don't have the car engine running when you jump. Then you won't be putting more than 13 volts across the bike battery and won't jolt it so bad.

Answer 3

I don't know why people are telling you its not good for the bike. I have been a professional machanic for 25 years and have done it and seen it done many times with no problems. Sure a car battery is capable of supplying alot more amperage, but, its still 12 volts. the systems on the bike only use what they are designed to use. For instance, you could hook up a light to one battery or 1000 batteries (in parallel) the light wouldn't burn out, just stay lit a lot longer.
Unless you have some sort of existing short or other electrical problem it will nto be or cause a problem.

1/12/07
Well, Mr. Nomad first you said it was amperage, then you quote an article that says voltage spikes, which is it?
I'm saying that CORRECTLY done there will be NO voltage spikes and NO problems from excess amperage.

Answer 4

george b says the same thing I did last time.
Big battery or small, it's still a battery. 13.8V is still 13.8V. The biggest problem with jump starting a motorcycle is getting at those small terminals. Like anything motorcycle, being careful is important. I've jumped a bunch.
At least notAminiVANmama is honest.

I had a Suzuki with a garden tractor battery.
I put a larger battery in my truck, lots of people do. No ill effects, all good. If you can jump start a small car, you can jump start a motorcycle.

Edit, 1-12: You begin with the bike's ignition OFF. Spike across open switch? NOT happening. I'm not a (paid) mechanic. I just own old stuff.

Answer 5

Yup. Too much amperage. You wouldn't believe how many electrical systems on PWC's we've replaced over the years because people don't check the batteries before they go to the lake and try to jump start them with their car/truck.

Most motorcyclists have enough sense to know better. ;)

A battery tender is worth it's weight in gold...

Edit:

Ahhh... if I had a nickle for every time those so called veteran mechanics gave me or a customer bum information. Keep it up guys, it just makes my cash register go cha-ching!

Copied from the Oct 2003 issue of Motorcycle Cruiser Magazine;

Charging the battery is going to take some time. You may be tempted to try and jump-start your bike from your car or a buddy's bike. It can be done, and in the past I've certainly done it. However, many late-model motorcycles, particularly those that are fuel injected, utilize some sort of microprocessor. Computers are highly sensitive to voltage spikes, and nothing causes a spike like a jump-start. If you're unsure about the jump-starting procedure for your bike, play it safe and sit this dance out, at least until you can verify that jump-starting your bike is safe.
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Do your own research, there's plenty of info on the web and some practical experience at your local dealerships.

Answer 6

if you are going to jump a bike with a car than do it while the cars engine is not running to minimise the amps, ive seen some fry and some with no problems.

Answer 7

I really dont know the reason...sorry. But I do know my hubby keeps a battery jumper made just for bikes.

Answer 8

probally cause a car battery has at least 300 amp in it and a bike battery has about 100..... it would like using a tazer to start a heart... it could work but could cause a lot more problems then it is worth....

Answer 9

simple.............amperage...a car battery is way to high ....it will fry your stator in your charging system