A sad fact in a motorcycle’s life is that motorcycle battery issues are generally only addressed when it is too late (i.e. the battery is already dead and/or you are stuck on the side of the road). However, there are some signs a battery is dying and needs some attention.
1) It is more than “4-ish” years old. Batteries have a finite life, so try to keep track of when your last battery was installed (check for date stamp on battery). Good preventative maintenance is simply to change a battery when it gets close to the end of its serviceable life.
2) You have been regularly letting your bike sit for long periods without running it (a motorcycle battery will lose about 1% of its charge per day when not run). Batteries need to be used to stay healthy. If you are guilty of not riding, take your motorcycle out for a long ride, including a nice stretch at highway speed. This might remedy the problem; otherwise, you may need to replace.
3) You have discharged your motorcycle battery completely several times. Batteries can really only handle this a couple times before being unable to take a full charge again.
4) If you go to start your engine and it “struggles” more than usual, it is possible your battery is not holding a sufficient charge (hovering too low in the acceptable range). This sort of “test” really requires “knowing” your bike. We think of motorcycle batteries as being 12V, but they actually hold more and more is required to start the bike. For example, a fully charged battery at rest should be between 12.6 and 12.75 volts. If a battery reads 12 volts at rest, it is almost fully depleted. The full range of the battery is from just over 14 volts (when being charged by the bike running at high RPMs) down to 10.5 volts (under heavy load, for example, when the lights are on and the bike is being started).
5) Use a multi-meter and test your battery’s voltage range. You can test the bike while it is off to see if the battery sits around 12.6 volts at rest, or you can run the bike and test voltages through a range of RPMs. As RPMs increase, the battery voltage should increase closer to 14 volts temporarily as the battery is being charged. Keep in mind though that if the voltage doesn’t increase at higher RPMs, this could point to an issue with the alternator. It is actually the alternator’s job to charge the battery.
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