Jumping battery from a car?

[masterh]

so I was having low power problem.

When I was driving in a same gear, it was speeding up slowly (so as rpm) and just works fine again. it died at stop light sometimes too.

anyways, the battery was low. so I hooked it up to car battery (done it before several time on this bike)

it was firing but if I don't rev, it kept dying. I felt like it wasn't getting enough gas.
the rpm couldn't go over 4000 in netural either.

anyways, after it died, it doesn't start ever again.

I spoked to the mechanic and he said maybe I fried the ecu.

I check the fuses but  those are fine.

Is it very stupid thing to hook up the battery to car's battery? (the car was running)

[Düb Lüv]

if you jumped your bike from a car that was running, you probably have some serious damage now. it would have been fine if the car wasn't running and just jumped. when a car is running the charging system can/will damage a motorcycle's electrical system.

[Howie]

Using a car battery to start your bike is fine, a running car, not so fine.  Chances are good  the ECU is OK though.  Did you check the 40 amp fuse for the voltage regulator?  It is mounted outside the fuse box.  Year and model will help us tell you where it is.  Also, try a known good battery.

[masterh]

I just checked the fuses that's in the box on the right side(I think there are 6~8)

it's 998
does it look like regular fuse? (like thsoe ones in the box)

Using a car battery to start your bike is fine, a running car, not so fine.  Chances are good  the ECU is OK though.  Did you check the 40 amp fuse for the voltage regulator?  It is mounted outside the fuse box.  Year and model will help us tell you where it is.  Also, try a known good battery.

[Bizzarrini]

Could jumping the bike from the battery of a running car also do any harm in a carbed bike? I tried it a couple of time with my old battery and never had any problems...

[ducpainter]

Could jumping the bike from the battery of a running car also do any harm in a carbed bike? I tried it a couple of time with my old battery and never had any problems...

IMO it depends on how you make the connections.

If you make all the connections at the weak battery first and then the last connection you make is the negative at the good battery I think you're fine running or not.

I believe it's the arcing that occurs when you connect the positive cable at the weak battery last that causes the damage.

howie will correct me I'm sure.

[64duc]

 Check your plugs first. Sounds like you might have fouled one and then the other.

[masterh]

yeah I checked the big fuse by the battery. it looks ok

I couldn't locate 2 fuses by the rear subframe though.

well, if I fried ECU, that would be $200 mistake since I can get used one for that price

Using a car battery to start your bike is fine, a running car, not so fine.  Chances are good  the ECU is OK though.  Did you check the 40 amp fuse for the voltage regulator?  It is mounted outside the fuse box.  Year and model will help us tell you where it is.  Also, try a known good battery.

[mitt]

In my opinion, as long as you connect things correctly, you could start / run your bike from a running mack truck.   It is a 12V (or 14V if running) voltage source, that feeds current to loads.  Your bike is a "fixed load", for example, say 40A.  If you have a voltage source that can provide 50A, or 100A, the bike will only draw the 40A it needs.  Now, if the bikes battery can only provide 25A, but the bike wants 40A if available, then I could see an abnormal situation, and possible damage, but that seems like a poor design.

I like to think of it like you are plugging an appliance into a house that has a 200A main, or 400A main, it will work in both.  Maybe I am missing something though.

I have run my bike without a battery, just using my running pickup and jumper cables.

mitt

[Howie]

Most of the time you can get away with using a running car to start your bike.  There is a chance of a voltage spike if you disconnect while the car is still running, but highly unlikely since the battery should take care of that.  It is more a matter of good practice not to run the car since a car battery is more than capable of starting the bike, so why take the chance?

[suzyj]

I like to think of it like you are plugging an appliance into a house that has a 200A main, or 400A main, it will work in both.  Maybe I am missing something though.

It depends on the state of charge of both batteries, and whether the car is running.

Worst case, if you've got a really flat (10V) battery on the bike, and a car running with a large well charged battery at 14V, you'll get a big voltage across the jumper cables, so will push a lot of current into the bike battery.  It could be many tens of amps, depending on how heavy the jumper leads are, and how you connect the two.

Better to connect to a non-running car, as then the voltage difference (and thus the current) isn't quite as big.