Can a motorcycle battery jump start a car?

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A motorcycle battery can be used to jump-start your car when your car’s battery is low.  This question has been asked many times and I was so curious that I decided to try it.

Can a motorcycle battery be used to jump-start a car? A motorcycle battery can be used to jump start a vehicle if it is not in use.  Connect both the positive and the negative ends of the jumper cables with the batteries.  Have one person rev the motorcycle to around 4000 rpm’s and have the second person try to start the car.

You can also check the following things to help you start your motorcycle battery: the size of the engine, the cold cranking amps, the temperature and whether the car is starting in short bursts.

If you’re trying to start a car with a battery that has been removed from a motorcycle then it will probably work under certain circumstances, such as if the engine is warm.  The chances of it starting with the motorcycle battery are higher if the car’s engine is smaller.

How to Jumpstart a Car With A Motorcycle Battery

If you want to start your car using the motorcycle battery, ensure the motorcycle is on. If the motorcycle is in motion, there is more current available to charge the car battery.

You may find it helpful to have someone help you.  The first person should rev the motorcycle to around 4,000 rpm’s while the motorcycle is in neutral and sustain it to that rpm.  The second person should try to crank the engine. With some luck and good timing, the bike should start.

There are many people out there who say that revving the motorcycle won’t help, but they’re misled. It will make actually make a big difference because you’ll be creating a higher amount of current, and with the jumper cables hooked up correctly, that excess current will be transferred to the car battery and help start the car.

Some people don’t understand that a motorcycle battery is less powerful than a car battery which is why revving the motorcycle to get the higher current to the car battery is important.

If you happen to be stuck with just a motorcycle battery but no motorcycle, you’re in luck because it’s still possible to jump start a car battery from an isolated motorcycle battery if it is warm outside. If it’s too cold then you might only be able to start a small engine.

A motorcycle battery that is fully charged will produce around 12.6 volts when it is turned off. If the motorcycle is not connected, this could be enough to jump-start the battery.

But you’ll have better luck with a motorcycle battery that’s connected to a motorcycle; while it’s running, the motorcycle battery and charging system will have between 13.5-15 volts, which makes a huge difference when trying to start a second vehicle from it.

Cold Cranking Amps Are Required To Jumpstart A Car From A Motorbike Battery

Every automotive battery designed for powering a vehicle will have a Cold Cranking Amps, or CCA.  Cold cranking amps is a measurement of the power output of that battery at 0°F for 30 seconds.  Car batteries are usually rated with higher CCA’s because their engines are bigger and they need more amps to turn the crankshaft.

Every car has a specification in its owners manual of how many CCA’s the battery should have in order to start the car, but that’s for regular year-round use. It is possible that for a one-time use you can get away with having less CCA’s than what is listed.

Depending on the engine size, an average car battery will have 200-700 cold cranking amperes.  But be sure that when you buy a replacement battery you get one that has equal or greater CCA’s than the manufacturer recommends, or you might have another dead battery sooner than you would like.

Smaller car batteries generally take between 200-400 CCA while V8’s with larger batteries are closer to the 700 CCA range.  Buying a battery with much higher CCA than your original battery had is just fine, just make sure it doesn’t have less CCA’s than the original battery.

The average motorcycle has between 200 – 400 CCA as well which is why it is completely possible to jump start a car using a motorcycle battery. This is also why you’ll have better luck with jump starting smaller cars compared to bigger cars, though jump starting bigger cars is completely possible using a motorcycle battery.

Comparison of the number of cylinders on a car and a motorcycle

The number of cylinders of the car that you’re trying to start makes a huge difference on whether you’ll be able to crank it over using the battery from a motorcycle.  A large V8 will require twice the effort to turn it over than a small 4-cylinder car.

You have a good chance of getting the car started if there are only four pistons you need to push up and downward along the cylinder walls.  For a motorcycle battery, less friction is better.

No matter how many cylinders you have on your motorcycle, they will not affect the ability to start the car. The stator, which is the only part of the motorcycle that has any bearing on whether the bike can start the car, is the most important.

The motorcycle stator outputs a certain voltage and current to recharge its own battery, so that’s the current that the car will see when you put the jumper cables on. Your chances of starting your car are greater if you have a larger stator. Click here for more information about an article I wrote. It explains in detail what a stator is.

According to my experience, I have not seen a bike battery start a V8 motor.  However, I have seen it start a 4 cylinder engine. To produce enough current to drive 8 pistons up or down, a motorcycle battery must have very high cold cranking amps.

The temperature of the car engine

It shouldn’t surprise you that a warmer engine will start more easily than a cold one. Because of friction, a warmer engine will start more easily. Colder engines are more likely to have friction and require more current to start the engine in order to turn.

The fuel lines in the car’s engine will heat up and combust faster if it is warm.  This will allow you to start the car using as little as possible current from your motorcycle battery.

A motorcycle battery could only start a big engine if it was really hot.  Otherwise, I think you would only be able to start smaller car engines if it’s cold outside.

Don’t Make This A Regular Habit

Motorcycle batteries were not intended for cars, but motorcycles.  There are a lot less plates inside a motorcycle battery because they don’t have to push out as much current in order to start a motorcycle engine.

Trying to start a car engine with a motorcycle battery isn’t good for the motorcycle battery because it draws a much larger amount of current than it was intended to. That quick discharge of a high volume of current isn’t healthy for a small battery, especially because motorcycle batteries aren’t intended for deep cycling.

This should only be done in an emergency.  Then, you will need to visit an auto parts shop to get the right battery for your vehicle.  Using this method won’t really create any safety risks, it’s just not advised for the long-term health of the motorcycle battery.

Make small, slow turns of the engine.

One key point to remember when you’re trying to start your car with a motorcycle battery is to try and start the car in short bursts. While trying to start the car, don’t hold the key and crank for a long time, you’ll discharge all the current very quickly.

Turn the key in short bursts and if it doesn’t start right up like it normally does then let it sit for a few more minutes while revving the motorcycle engine and try again.  I’ve done it and seen it work firsthand.

Similar Questions

Can a car’s battery jump start a motorbike? A car running can jump-start a motorcycle.  This works great and I’ve done it dozens of times.  Because the motorcycle battery usually is tucked up by the frame be sure you don’t touch the positive terminal to the motorcycle frame or you’ll get quite a shock and some sparks.

How long can a bike sit still before its battery runs out? A typical motorcycle battery will eventually die within 2-4 months of not being used.  Older batteries last for 3-5 months on average. You can find more information about this topic in our article on batteries.

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