Can I jump start a motorcycle?

yes i do it often Ok, that answer works-- I've also done it on more than one occasion-- but there are some things to consider. I'll try not to get too technical, but a lot of people misunderstand so I want to be complete. First we have to look at lead acid batteries as are used on both cars and motorcycles. When charging, a lead acid battery heats up. If you try to charge it too fast, it will heat up too much and damage the battery. You've probably noticed that a car battery is a lot bigger than a motorcycle battery which means that a car battery can be charged faster than a motorcycle battery. Consequenty, the alternator voltage on your car is probably around 14 volts (the alternator voltage on my pickup is nearly 15 volts while some of my smaller cars are thirteen point something). Both because the battery can't be charged as quickly and because the alternator is much smaller on the motorcycle, the alternator voltage is much lower. How fast the battery charges depends on the amount of current going into it which is directly related to the difference in the battery voltage and the charging circuit voltage. A fully charged car or motorcycle battery is at about 12.6 V. Ok, that's the technical part. Even if you didn't understand what I just said, pay attention to what follows and you'll probably be ok. When your car is running, the electrical system is operating at a higher voltage to keep the battery charged. The electronics in your car is designed to handle the higher voltage. Electronics in your motorcycle may or may not be able to handle this higher voltage. When you jump start a motorcycle from a car, make sure the car isn't running to avoid damage to the electronics on your motorcycle. Older or more basic motorcycles may be ok because they don't have much in the way of electronics but on newer motorcycles-- especially if you have fuel injection or electronic ignition-- serious damage can occur if the car is running when you jump start the motorcycle. So, only jump start if you must and always jump start with the host car not running. Trust me on this. You don't need the potential heartache.