So many questions about motorcycle functionality boil down to the electrical system. Come the electric vehicle revolution, we’ll have to be as good at diagnosing electrical systems as we are now at changing engine oil, rebuilding carburetors and swapping fuel filters.

If you have been riding a while, you probably have a good sense of what’s wrong with a given motorcycle by the sound and feel of the bike. That will only take you so far, though. When a bike is running wrong, or won’t start, and it “feels electrical,” what then?

I always recommend that riders start with the simple and cheap stuff and go from there. Even if your battery is relatively new, a battery can be bad from the factory. Knowing how to test one is key. A motorcycle’s electrical system revolves around the battery. It’s always best to test that first, so you can rule out problems one by one.

If you ride motorcycles and don’t already own a multimeter, it might be time to add that particular tool to your arsenal. Using one correctly is the best way to figure out whether your battery is good, and the problem lies elsewhere. Or, your battery is bad, and you’ve found your problem!

Modern motorcycles run on a 12-volt electrical system. That means your battery is a 12-volt battery. Too often, riders think that when their bike’s battery reads 12.0 volts, it’s fine. Unfortunately, that’s pretty far from the truth. At 12.0, your battery is half dead. Does that mean it will still start your bike? It depends on the bike.

Battery State of Charge Chart

Whether your bike has a traditional wet lead-acid battery, an Absorbed Glass Mat (AGM) or Lithium-ion, a twelve-volt system is a twelve-volt system. Without sufficient cranking amps to get that starter turning, you’re not going anywhere.

Here’s a great, quick video that will teach you to use a multimeter to test your bike’s battery:

What’s a Load Test?

If you’re wondering why you’d keep the multimeter on the battery through a start cycle, it makes a good “load test.” A load tester lets charge out of the battery in a measured way, and tests how well the charge bounces back. A motorcycle starter draws heavily from the battery. A battery can show plenty of volts on the multimeter at rest, but the moment a load is drawn, those numbers can plummet. Ever go to start your bike, find the dash lights up and lights turn on, but the moment you hit the starter, everything goes dim and all you hear is a faint clicking? Yup, your battery is dead. 

When Do I Need To Replace My Battery?

Some motorcycle batteries last most of a decade, and some die inside of three years. Completely discharging the battery is a great way to take years off its life. Some day you will find yourself in the above scenario, and instead of riding you will be recharging your battery. Use that time to shop for a new one. Recharging will get you home, but you’ve seriously crippled your battery by discharging it, and it will die on you again very soon.

Now that you’re armed with a little bit of knowledge about your bike’s electrical system, stay tuned for upcoming tutorials on how to add electrical accessories to your motorcycle.