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With today's cars being almost exclusively automatic, you usually need to jumpstart a dead battery on the road.

What about motorcycles nowadays? Most are electric start with no kick starter.

Assuming you can access the battery, is it possible to jumpstart a modern bike? I know that some car computers/ignition systems don't like it, but what about bikes?
 

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Yes, indeed. And with fuel-injected bikes you can't even roll-start them unless enough battery juice is left to run the fuel pump. I'm headed off on a 200 mile round trip this PM and, as usual, my little compact jump-starter will be tucked away in my bike bag...just in case.
 

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Yep, I have one of those too.
Saved my butt a couple of times.
Saved some woman a tow last year.
 

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Yes and no, I'd be leery about having car running. For one there is no need, the car battery is more than enough amp, and because many alts can have up to 100 amp running through them when at full load and jumping tells charging system to go pretty high in the demand. Many bikes can have only around a 30 amp fuse as the main one and that should blow if you put in more than it. Many car alts typically fuse around 175-200 amp in the main charging leads now.

The bikes may not like the sometimes higher volt many cars can put out too, up to 15 now.

One issue is the computers often tie into car charging now and if the bike has say a shorted battery could it do damage to the car with it running? Some cars now won't even running jumpstart other cars, they sense something is whacky and will not output. Cars sense a lot of things based on battery volt and amp history now, if you risk dropping system volts low you can make the car act up with the entire system live, better not to look for trouble if you ask me.

Can't imagine in today's world people being still unlearned enough to connect cables up backwards on computer stuff but still you get some who haven't gone through a $1000 repair due to doing it on a modern car (or bike).

Now a big problem seems to be the jumping will commonly not work due to the thousands of Chinese cheap jumper cable sets that are not thick enough in gauge to carry enough power to properly do a jump.
 

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I for one hate those things, commonly they can be bad just like a battery if you don't keep them regularly charged and why add one more thing to have to mess with. If you are rescuing a bike a car is commonly there already and ready to go. I used to sell those boosters too and people came back trying to return them all day long when they went bad to not jump off and commonly you are broke down when you find out so double broke then. We kept one in the store where we sold them and quit after throwing several away before they could get any use out of them and finally I talked the store into not using them any longer and no problems then, we simply used the shop truck which was there anyway.
 

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I for one hate those things, commonly they can be bad just like a battery if you don't keep them regularly charged and why add one more thing to have to mess with. If you are rescuing a bike a car is commonly there already and ready to go. I used to sell those boosters too and people came back trying to return them all day long when they went bad to not jump off and commonly you are broke down when you find out so double broke then. We kept one in the store where we sold them and quit after throwing several away before they could get any use out of them and finally I talked the store into not using them any longer and no problems then, we simply used the shop truck which was there anyway.
Interesting. My experience has been exactly opposite, and universally satisfactory. Never once when I have used it has any other source of a jump been available.

So -- different strokes, different folks...
 

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The charging itself will at some point ruin them, they only recharge so many times and the amp amount they can boost drops with the passage of time. It's why I won't buy anything cordless, except for my 12 volt drill, which I converted to using car battery too when the batteries did the exact same thing as those jumper packs, go bad in a year of not using them. $70 apiece for batteries, no way. I hate lith ion batteries, they just get in my way.
 

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The battery on my bike, and a lot of bikes are not as easily accessible so connected something to it with it not being pre-prepared is not something your going to do quickly.
 

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You are incorrect.

The alternator on a car puts out way more amps than a motorcycle stator. The extra amps will blow the fuse. The car has to be off for it to be safe.
In order for the fuse to blow, the motorcycle electrical system would need to draw more amperage than the fuse is rated for.

Nothing in the electrical system would draw this much amperage through the fuse at any time unless there is a short.

The motorcycle battery and starter only draw the amperage needed, and of course you know that the starter is not protected by the main fuse.

This is simple basic DC circuits we are talking about here.

Amperage is determined by voltage divided by resistance (ohm`s law).

You could hook up to a million amp battery, and as long it is 12 volts there will be no damage.

I`m not just repeating what I have read on the internet.

I`m basing my comments on 45 years as a professional aircraft mechanic, and over 50 years working on cars and motorcycles.

You need to do some studying on DC circuits.
 

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No, I`m not incorrect, and I`m not just repeating what I have read on the internet.
Basing my comments on 45 years as a professional aircraft mechanic, and over 50 years working on cars and motorcycles.
In all that time, I have never once heard or seen a main fuse blown by jumpstarting a motorcycle as long as the cables are connected.

You need to do some studying on DC circuits.

The battery in the car can put out 500 amps, much more than the alternator in a car.
The fuse will not instantly be blown.
I assure you a 15amp fuse blows when you hook an 80amp alternator to it. Its literally the sole function of the main fuse.
 
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