How to Jumpstart a Motorcycle with a Car

This article reveals how to jumpstart a motorcycle with a car without damaging the motorcycle. Yes, it can be dangerous to jumpstart motorcycles with car batteries, and even manufacturers discourage it.

how to jumpstart a motorcycle with a car

It is dangerous to jumpstart a motor vehicle, including a motorcycle, with electrical cables. The reason is that invariable final connections cause a spark, and it may result in an explosion and not just flames.

Besides, a lead-acid battery in typical internal combustion vehicles produces hydrogen gas during the work cycle. Not being careful can result in burns, and it is worse when the spark is closer to fuel or hydrogen gas.

Can you jumpstart a motorcycle with a car?

Yes, you can jumpstart a motorcycle with a car battery. A typical car battery has a higher amperage than a motorcycle battery, making it possible to jumpstart your motorcycle using a car battery. However, you must not make it a habit to jumpstart your motorbike using a car battery always; it must be during emergencies only. Note that this practice can damage or degrade your motorcycle components and void the warranty on the battery.

How to Jumpstart a Motorcycle with a Car

Regardless of the dangers, you can jumpstart your bike safely with a car battery. What you require is a jumper cable to jumpstart the motorcycle with your car.

Below are the steps regarding how to jumpstart a motorcycle with a car:

  1. Disable Ignitions

First, turn off the ignitions on the car and motorcycle. It is important to disable ignitions on both motor vehicles to prevent ruining the voltage regulator or motorcycle battery.

  1. Connect a Red Jumper Cable to Positive Terminal on Motorcycle

Next, connect one of the red jumper cable clamps to the positive terminal of the battery of your motorcycle. The red jumper cable clamps must be connected to the red positive terminal on the motorcycle battery.

Make sure the black clamps on both sides of the jumper cable do not touch anything.

  1. Connect Red Clamp to Positive Post on Car

Now, connect the other red clamp to the car battery’s positive post. Note that positive goes to positive.

  1. Connect Black Clamp Near Car’s Negative Post

On the car battery, connect the near the car to the negative post. Note that the negative posts in most new cars sit several inches away from the battery. So, you can use it to connect the clamp if it’s available.

After connecting the black clamp near the negative post of the car, the jumper cable is energized, and you must handle it cautiously.

  1. Connect Black Clamp Near the Motorcycle

Now, connect the black clamp near your motorbike to an unpainted area on the motorcycle frame. It should be away from the fuel lines, fuel tank, and motorcycle battery.

The connection might cause a spark due to the difference in voltage between the motorcycle and car. It is normal for it to spark, and you should keep following these instructions to avoid an explosion or fire.

  1. Don’t Turn On Car’s Ignition

Make sure not to turn on the car ignition. Otherwise, the cable connections can damage or degrade the electronic system.

Some persons start their car, but only if the jumper cable is connected properly and the battery condition is excellent.

  1. Start Your Motorcycle

Start your motorcycle normally, but crank less than 15 seconds because motorcycle starters are designed lightly and not cranking for longer periods.

If the motorcycle does not start within or after 15 seconds of cranking it, something is not OK. Do not crank the bike again. Check other systems in the motorcycle as the starter cools.

Is your stop/run switch on? How about your fuel level? If everything seems okay, start the bike again after the starter cools.

  1. Disconnect the Clamps

When the motorcycle starts, disconnect the black clamp on the motorcycle and car. Next, disconnect the red clamps on the motorcycle and car. After disconnection, the cable is not energized anymore.

What Happens if You Jump Start a Motorcycle with a Car?

Typically, when you start a motorcycle with a good motorcycle battery, the voltage drops the battery voltage to 12V or less due to the load. So, you are not supposed to crank the motorcycle longer than 15 seconds, or it burns the starter.

However, when you start a motorcycle with a good car battery, the car battery does not drop below 13V or thereabout on a small load of a motorcycle you crank. Except your battery is shorted and the jumper cords smoke, you’d notice that the motorcycle cranks excessively. If you crank for a longer period, it damages the motorcycle.

If you power the car, the alternator sources more current needed by the motorcycle, such that the motorcycle does not pull the 14 or thereabout volt. Meanwhile, at 14 volts, your starter coils heat up and may fail.

In this case, put off the car and use the car battery to jumpstart the motorcycle. Cranks are one-second bursts with a few seconds of calm in between.

When hooking the cables, start with the positive (+) and negative (-) on the bike, then negative on your car, and positive. Typically, cars have bigger batteries and more room to avoid shorting things. Make sure to look for smoke on any part and try.

Do you start the car when jumpstarting the motorcycle?

It is not advisable but OK to start or leave the car running when jumpstarting a motorcycle. It may ruin or degrade the motorcycle voltage regulator or battery. A decently charged car battery can jumpstart a motorcycle easily (depending on the car and motorcycle).

Most motorcycles and cars feature a 12V charging system. So, just hook up the jumper cables after turning off the car and start the motorbike. If the car is running, the alternator puts out 14.4V @ 100+ amps that can damage the ECM and Regulator/Rectifier assembly. This is a possibility though, but some bikes can put out 14V, so it is no problem for those.

Amperage is not a big a factor as people make it out to be. Think about it like this: you can wire a tiny 12v LED to a car battery, the same battery that can crank a high compression V8. The lack of an electrical connection does mot imply the delivery of full amperage.

A fully charged car battery should measure at 12.6 volts or more. When the car engine is running, it should be 13.7 to 14.7 volts. If you do not have a multimeter to read the battery voltage, test your electrical system by starting the car and turning on the headlights.

But hey, I have jumped motorcycles with a running car a few times without issue. After the first few times, get a mobile jump/charge kit.

An old school bike that runs on 6v electrical systems may be fried by a 12v car system. However, this is generally long gone. You can jump lots of 12v bikes off a car without sweat.

If you fear some cable could burn from ‘too many amps’ going through it, there is a protection in your bike built in for it. You may call it the fuse box. If anything is burning from too many amps, it will be one of the fuses, which is what they are built for.

Final Thoughts

After jumpstarting a motorcycle with a car, allow it to run up to 30 minutes at highway speeds before it can start with its battery. Nevertheless, it will not charge fully; you can charge it after the ride.

Alternatively, you can charge your motorcycle battery instead of jump-starting it.

Lastly, if the motorcycle has a 6V-charging system, do not jumpstart with a 12V car. Instead, you can bump start it. Meanwhile, should you buy a motorcycle or a car?

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