The battery is an intricate part of fundamental motorcycle operation.
Whether you’re on an old vintage-goldie or a high-tech modern moto-masterpiece, the battery is critical to starting the bike and powering your headlights, gauge displays, and your ECU and fuel injection systems when applicable.
The battery can perform these essential functions thanks to a charging system that charges the battery while riding; multiple problems might be the culprit behind why your motorcycle battery won’t charge, and here are the 11 most common:
1. Battery Terminal Connectors Are Loose or Poorly Connected
This is always the first thing I check since I’ve seen too many good riders and wrenchers on the verge of mental discombobulation when they realize it was just a loose screw way too late in the game.
One of the most common and easily correctable reasons a motorcycle battery won’t charge while riding is because of a loose or inadequate terminal connection.
The terminals are the two small metal components that extend out from either side of the bike’s battery.
If a motorcycle has a faulty terminal connection, your battery won’t replenish sufficiently since the charging system energizes the battery through its terminals via the battery cables.
If your terminals are loose, the good news is this is about the easiest thing to fix on a bike, period. A few quarter-inch turns until it’s tightened to spec and you’re back to charging while cruising.
2. A Wire Ground Has a Short
A short in your bike’s ground wire can be difficult to pinpoint, but it’s certainly a common reason a battery has trouble charging. A faulty wire ground on a motorcycle can first manifest as the intermittent failure of various electrical components, but it doesn’t always stop there; you could end up with a dead bike that won’t turn over.
If your motorcycle has faulty ground affecting the charging system, your battery won’t charge while you’re riding.
In other cases, you might notice the battery’s charge being higher and lower than spec.
If you suspect faulty wire grounds are the reason your motorcycle battery won’t charge while riding, start by using your owner’s manual to locate and inspect the condition of all your wire grounds. If a shorted-out wire is preventing your battery from charging, it’s a cheap and straightforward replacement, which is why it’s high on the list of early troubleshooting.
3. Corroded or Contaminated Battery Terminals
If the terminals are corroded from exposure to moisture or harmful riding conditions, that rust forms a seal between the terminals and the cable the stator uses to charge the battery.
If the corrosion is light, you might be able to salvage the battery by cleaning it, following the safest procedures possible, first removing the battery from the bike.
4. Battery Sulfation; the Buildup of Lead-Acid Sulfate Crystals
Our chemically inclined readers saw this one coming; the buildup of battery acid crystals seals the terminal and prevents it from charging during use in the same way corrosion does.
A sulfated battery can not only prevent the battery from charging while you’re riding the motorcycle, but it also results in power loss and dips in engine performance.
You might notice your battery is completely dead after a long rip, or it could just be that you’re seeing longer charging times. Either way, sulfation will absolutely interfere with your bike battery’s charging process.
Sulfation isn’t necessarily indicative of a deeper problem—all batteries incur sulfate crystal buildup slowly every time they’re used. That said, this buildup starts to incur much more rapidly if the battery is overcharging or not getting charged enough.
Letting a battery sit unused in a discharged state will also accelerate how sulfate can accumulate.
The best way to prevent sulfation is to use a high-frequency-pulse-oriented desulfation charger while the battery is sitting. As my description implies, these chargers use frequencies to dissolve sulfate crystals. It also dissolves the new sulfate crystals as they attempt to form, preventing more buildup. Get rid of the sulfation, and your battery will go back to charging while the bike is in use.
5. The Bike Has a Faulty Stator
Your stator is the next component to inspect if your terminals are connected and clean and your wires are grounded. The stator on a motorcycle does half the job of a car alternator; a stator has a more straightforward operation.
The stator’s job is to charge the bike’s battery while the motorcycle is riding, making it a go-to troubleshooting step on a motorcycle battery that won’t charge while the bike is being used.
If the stator fails, and all parts fail eventually, even on the best-made bikes, you’ll be powering your bike solely on whatever voltage is left after cranking her ignition. A bike battery simply can’t power a bike without constant recharging, which it gets from the stator.
If a bad stator is a reason your bike’s battery won’t charge while riding, the only real fix is to replace the stator, preferably with an OEM-suggested one.
6. Your Regulator/Rectifier is Malfunctioning
Your motorcycle has a part called the Regulator/Rectifier, which does the other half of a car alternator’s job. As the name implies, it regulates the battery’s voltage and charging by rectifying the AC generated by the engine during use into a DC—only the latter of which the battery can hold.
If your bike’s R/R is failing, not only will your bike’s battery have a hard time charging, but it might also explode from overcharging since nothing’s regulating the current. Even if it simply fails to convert the AC to DC, the battery can’t store the power, so your motorcycle battery depletes from standard operation.
7. Aftermarket Modifications and Add-Ons are Overworking the Bike’s Battery
Now I’m not here to judge y’all moto-maniacs for stinging out your bikes with performance upgrades and aftermarket flare. That said, the simple fact is that, while individually they may be putting a nominal strain on your battery’s voltage, the combination of phone chargers, LED fog lights, a day-care asking headlamp rig, under-glow, heated grips, heated seats, and a sound system upgrade all strain the bike’s battery during operation.
Suppose your aftermarket accessories work together to drain the battery faster than your charging system can convert power to charge it. In that case, your bike’s battery will undoubtedly have a hard time juicing during your joyride.
8. The Battery Itself is Bad
Another potential cause of a motorcycle battery that won’t charge while riding is that the battery itself has gone wrong. No battery lasts forever; bike batteries are no different.
The average shelf life of a motorcycle battery is between two and four years, though batteries can fail sooner depending on accessories, electronic groundings, etc.
Once a battery starts to fail, it loses its ability to hold a charge, meaning that while you’re cranking that ignition and running them high beams, your battery is being depleted. Eventually, it discharges entirely and never comes back to life.
A quick peek at your bike’s battery will reveal that it has an expiration date labeled onto it. If you suspect your bike’s battery isn’t able to charge while you’re in the saddle, check the expiration date. It might simply be time for a freshie.
9. Battery Cable Vibrates Loose
A battery that stops charging while riding a newer motorcycle is due to engine vibration, which causes a battery cable to shake loose.
While this can happen on old and new bikes alike, the latest motorcycles have a safety program that kills the bike if the battery cable comes unplugged. This is a safety precaution in place that prevents the loose cable from hitting a ground wire and causing a spark that could fry your bike’s electronics… or maybe worse.
If your battery died out of nowhere while you were riding the bike, it might be that the battery isn’t charging. It could be that a battery cable vibrated loose, triggering the bike’s automated shut-off response.
10. Battery Specifications Are Incorrect
If you’ve got the wrong size battery in your bike, it’ll cause interference with the charging process, which could lead to the battery not charging while you’re riding the motorcycle.
Some riders assume motorcycle batteries are universal, but that’s simply not the case. There are different sized batteries, but there are also different material types of motorcycle batteries as well. For example, a bigger-sized bagger or luxury cruiser often needs a bigger battery than a sports bike or naked cafes.
Some riders will try swapping a perfect battery from one bike to another and scratch their heads when the machine doesn’t take charge after a long ride. Check the owner’s manual for your specific make-year-model motorcycle battery.
That said, and we touched on this a bit in an earlier section about aftermarket electronic upgrades, some riders deck the wheels with bells of glory. If you’re running excessive electronic gear, you might need to go up a size in the battery. You’ll have to consult a tech who’s well-versed in your specific model motorcycle to make sure that it’s safe.
11. Owner Neglection of Motorcycle or Battery Upkeep
Now we’re not trying to ruffle any feathers here; the fact is that the most common reason a moto-battery stops holding a charge while the bike is in use is due to owner negligence. This doesn’t have to mean you’re neglecting the bike; you might be sorting it indoors and watching your riding manners all day long. But if you’re storing your bike indoors for long periods without use, the battery needs to be on a tender or a trickle charger.
Let me explain:
As we mentioned earlier, there are different batteries in different types of bikes. The motorcycle’s electronic systems are tailored for interacting with a specific battery spec. The plan that charges your bike while riding varies from moto to moto regarding discharging rate and depth, charging requirements, and electronic loading.
While the materials used vary from battery to battery, the leading cause of battery death is active material depletion. The fastest three ways to deplete the material and damage the battery so it doesn’t charge while you’re riding are:
- Only riding short distances prevents the charging system from restoring the battery to complete after each ride depletes its material.
- Failing to employ a battery tender or trickle charger; when storing a motorcycle for long periods of inactivity, the battery has to be maintained with the same attention to the protocol as the engine, chrome, finish, tires, fluids, fuel, etc.
- Overloading the battery during operation either by using the wrong size or with excessive aftermarket upgrades, as addressed in previous sections.
All three of these common battery depletion causes are improper ownership upkeep. Your bike’s battery is a pivotal part of the operation. Treat with as much TLC as you do the rest of the bike.
Still, no matter how good you take care of a battery, things can go wrong with any battery, which is why we gave our readers this convenient list!