Jumping A Motorcycle with a Car: Should you do it?

Being stranded on the side of the road with a dead motorcycle battery is not a situation any motorcyclist wants to find themselves in.  The temptation to wave a passing motorist down for a jump may sound like a good idea but there are some things to consider before you do so. 

First of all, jumping a motorcycle battery with a car battery is a safe and effective practice in theory. Many people who know a bit about car and motorcycle batteries don’t even give it a second thought. That’s because they know that motorcycle and car batteries operate at an output of about 12.6-14v in normal conditions; which, means the voltage is close enough for them to be viable jumping options for one another.

Still, not everything that works out in theory will work out under practical circumstances. There are very important factors to take into consideration before you try to jump a motorcycle battery with a car. 

Alternator Rating

Something that may give you pause before attempting this type of jump is the alternator power output rating. A car with a 100A alternator is capable of giving out 100 amps of power when the alternator shaft is running at a rate of about 6,000RPMs. A motorcycle with a 350 watt alternator is capable of outputting about 30 amps max. 

This difference in output rating could have a disastrous effect when the car battery is put in parallel to the motorcycles alternator charging system. The battery can become damaged and so too can its electrical systems if you are not very careful. The amperage of the car – the strength of the electrical current – may be way too much for your motorcycle’s electrical system to handle.

More than Circuiting

While the circuiting between a motorcycle and a car will match up for a jump, there are other factors at play. These factors could make this kind of charge dangerous. For instance faulty wiring in the bike’s electrical system could spark major issues when being fed with a significant electrical current.

If any of the electrical wires on the motorcycle are corroded the jump may not even work in the first place. Furthermore, a jump from a car may lead to a shorted starter armature in your motorcycle. This is a problem that is a lot more serious than a dead battery.

What you Should Know

In the end, you should only rely on a jump from a car if you are in a really desperate situation. In most cases a jump from a car to a motorcycle would probably work fine but if something is just slightly amiss you could have a much greater problem on your hands. If you are in a position where you must jump a motorcycle from a car, make sure to turn the car off first.

Companies like Matco make high output portable chargers that can jump motorcycles in a safer manner. So if you have the opportunity to avoid using a car to jump your motorcycle, you should definitely play it safe and take it.