Jump Starting a Dead Battery

Assuming that you have, or can get, a set of jumper cables when you find that your motorcycle battery is dead, getting the bike started is no big deal. But you can cause harm if you do it wrong.

A few tips here are NEVER use a charger with a boost feature to get your bike started. It will usually damage a radio if your bike has one. Always use a slow charge of a low amperage to charge a motorcycle battery (less than 10 amps) preferably around 2 amps would be ideal.

Connecting batteries in series is what you do when you pop a couple of cells into your flashlight. That is, you put the positive terminal of one battery into contact with the negative terminal of another. The result is that the voltage provided is the sum of the voltages of both batteries. This is NOT THE WAY to connect motorcycle batteries!!!

When you connect batteries in parallel, by placing the positive terminal of one into contact with the positive terminal of the other and the same with the negative terminals, then the voltage that results remains the same, but the amount of current that can be produced is raised. You need current to power your starter.

Always be sure that the batteries you will be connecting together are of the same voltage.

Always connect the same polarity terminals together when jumping a battery.


If you connect the opposite polarity terminals together your battery can EXPLODE!

Always wear eye protection when jumping a battery!


Batteries can explode from another cause as well: a charging battery creates hydrogen gas.

Make sure the vent tube on your battery is connected properly.

Make sure you are in a well ventilated environment - preferably outside.

Do NOT SMOKE while charging or jumping a battery as the hydrogen gas that is emitted from a battery is explosive.

Lay out your jumper cable so that the connectors are not touching each other. Then, connect the positive (red) lead of the cable closest to your dead battery to the positive terminal on that battery followed by connecting the negative lead (black) to your negative battery terminal. Be sure that these connections are firm , wiggle them a little in order to let the teeth (if any) on the jumper leads cut into the terminal metal posts.

Always start by making the connections on your dead battery.


Why? Because you cannot kill a dead battery! (If the loose ends of the jumper cable were to touch each other.)

It might be better if you connected the negative lead to some part of your bike frame rather than to the negative battery terminal in order to keep any potential sparks away from generated hydrogen gas. However, there cannot be a spark from a dead battery, connecting the leads to the dead battery does not yet create a circuit, and in the next step you will take pains to avoid a spark with the live battery.

Next, connect the positive (red) lead of the other end of the jumper cable to the functional battery's positive terminal. Again, wiggle the connection to encourage a good 'bite' of metal to metal. If you are unable to gain access to the battery terminals on the donor vehicle, (many are very inconveniently located), you can connect the positive jumper lead to the starter solenoid lead closest to the battery.

Finally, connect the remaining (black) lead to some part of the frame of the donor vehicle. Since the negative terminal of all modern vehicles have their negative battery terminal connected to the frame of the vehicle (called a ground), this is the same as connecting to the negative terminal of the battery. However, since this last connection establishes a live circuit, it is possible for there to be a spark when the connection is made. You want any spark that might occur to be as far away from the battery as is reasonably possible.

Though MOST vehicles today use a negative ground, you must check to be sure that is the case before you connect the jumper cables to the donor battery. You can still use it even if that vehicle uses a positive ground, but you must remember to connect positive to positive and negative to negative.


Generally speaking, it does not matter if the vehicle engine is running or not when you do this. The battery will be producing the proper voltage and current to do the job, and not so much that you might do harm.

If your battery is dead because it has developed an internal short, you can easily kill the donor battery when connecting it if the donor vehicle is not running at the time, but

If it is running and your battery is shorted you can damage the donor vehicle's voltage regulator or alternator system when you connect the jumper cables.


If the donor vehicle is not running when you connect the jumper cables,

DO NOT START THE DONOR VEHICLE while it is connected to your motorcycle battery.


While the starting current drain is not going to be a problem, the subsequent charging current to replenish the battery could be more than your motorcycle battery can handle.

You do not have to be in a hurry while the jumper cables are connected. Indeed, so long as those cables are connected the donor battery is charging your motorcycle battery. After a couple of minutes the charge might be sufficient for you to be able to start your bike using just your own battery. In any event, it is now time to start your motorcycle. It is usually best to simply leave the jumper cable in place when you start the motorcycle.

Let your motorcycle run about 15 seconds while the jumper cable remains in place. Then, remove the negative (black) lead from the donor vehicle's frame (assuming it was a normal negative-ground system). Again, this step could cause a spark, but because the connection is away from the battery, it poses no danger.

Now disconnect the positive (red) lead from the donor battery terminal. You must be very careful not to let the jumper cable leads touch each other at this time. To do so WILL KILL YOUR MOTORCYCLE BATTERY, possibly permanently!

Disconnect the jumper leads from your motorcycle battery (in any order - there cannot be a spark from doing so.)

Let the motorcycle idle (high - over 1,000 RPM) for a few minutes before you attempt to ride off into the sunset to give its charging system a chance to restore your battery.

Thank the person who donated the use of their battery to get you going again. You could have killed that battery if you had done it wrong, so he took some risk for you as well as provided his courtesy.