ATV batteries are considered consumables that eventually go bad and must be replaced. But how do you know whether a battery has gone bad or it just needs a charge?
Here are the most common symptoms that could indicate that your ATV battery is beginning or has already gone bad.
1. Slow Engine Cranking
The battery’s primary purpose is to power the electrical starter that, in turn, starts the engine.
When the battery becomes weaker, you notice that the engine cranks slower until there isn’t enough power to start the engine.
While slow engine cranking can be an early sign of a battery going bad, it can also just be that the battery’s state of charge is too low, and it needs a proper charge with an external charger.
ATV batteries are prone to draining faster than the ATV charging system can keep up. Battery draining can happen due to overusing power-hungry accessories such as an electric winch or when an electrical issue causes a parasitic amperage draw that drains the battery overnight.
Note that it is normal if the engine cranks slower in cold weather. The engine is harder to turn due to the engine oil becoming thicker, and the cold also reduces the battery capacity, even in healthy batteries.
2. The Battery Warning Light Turns On
Another early sign that could indicate that the battery is starting to go bad is when the battery warning light turns on in the ATV instrument panel.
Modern ATVs typically don’t have a dedicated battery warning light but a check engine light combined with a diagnostic code that tells you the type of issue.
A battery warning light or check engine light with a “system power” diagnostic code tells you that the system voltage is too high or too low. Several issues could trigger this type of warning.
- A faulty stator.
- A faulty voltage regulator.
- Loose, damaged, or corroded wiring.
- A battery that is too drained and needs a charge.
- A battery that is damaged and needs to be replaced.
The easiest way to troubleshoot a battery warning light is to charge it with an external charger to see if it charges and test if it holds a charge.
3. The Battery Won’t Charge
Often, you’ll find that a proper charge with an external charger will bring the battery back to working order. But if the battery has gone bad, it may no longer be capable of taking a full charge.
A modern automatic charger usually refuses to charge a bad battery. When a battery becomes heavily sulfated or if a cell is dead, the charger notices in the initial stages of the charging process and won’t attempt to charge the battery.
If you use a conventional manual charger, the battery may seem to charge as usual, but when you test the voltage afterward, you find that it did not charge as it should.
Use a multimeter in the 20V DC setting or a volt-meter to read the battery voltage. The red lead connects to the volt (V) port and onto the positive battery terminal. The black lead connects to the COM port and goes to the negative battery terminal.
- A healthy battery, when charged overnight, should reach a state of charge of at least 12.4V. If it doesn’t, the battery is too sulfated and needs to be replaced.
- It has a dead cell if you cannot charge the battery above 10.5V.
- If the battery reads 0V, it has an internal short circuit.
Some modern chargers have a “Recondition” mode that is designed to remove some of the sulfation. This feature can be useful to restore a battery in the beginning stages of sulfation.
Note that some smart chargers refuse to charge an otherwise healthy battery that’s been drained overnight. A completely drained battery has not necessarily gone bad as long as you make sure to charge it immediately.
Check out this guide to troubleshoot a scenario when a battery won’t charge.
4. The Battery Won’t Hold a Charge
Often, you will find that a battery you suspect has gone bad seems to charge as normal but loses its charge after just a day or two. A bad battery can lose its charge even when disconnected from the ATV.
When a battery has finished charging, it holds a higher but temporary surface charge that goes away after a couple of hours. When you read the voltage, it may indicate a healthy level above 12.4V. But after a day or two just sitting on the bench, a rapid self-discharge rate may have caused the voltage to drop well below your previous reading.
Battery not holding a charge can happen when fluid levels are low on a serviceable battery (conventional lead-acid battery with removable caps).
When a sealed battery no longer holds a charge, it has likely gone beyond repair and needs replacement.
5. Bulging Battery Casing
Overcharging is when a battery is charged at too high of a voltage and can cause permanent damage to the battery. Typical signs of overcharging are when the batter loses its capacity, and the outer casing looks bloated with bulging sidewalls.
Bulging battery sidewalls are a sure sign it needs replacing, but you also need to find the source of the overcharging condition.
Using the wrong charger or wrong charge mode for the battery type can cause overcharge, but so can a defective voltage regulator.
6. Cracked Battery Casing
The battery’s outer casing is made from a rugged, impact-resistant plastic material that can handle most of the abuse rough ATV riding can throw at it.
But from time to time, the outer casing may crack, spilling out the internal fluid, which has an immediate negative effect on battery performance.
Inspect the battery to look for physical damage. You may need to disconnect and remove the battery for a good view.
With any signs of leaked battery fluids or cracks in the battery casing, you must replace the battery before using the ATV. If the leak is small, you may not find liquid battery acid but look for white residue in the battery tray from dried battery fluid.
7. Misshaped or Melted Battery Casing
A battery casing can melt and become misshaped if exposed to too high temperatures. That is why it needs to be installed at a safe distance from the exhaust system.
If the casing has defects near the battery terminal, it can be caused by a short and should qualify for a battery replacement.
8. Lose or Damaged Battery Terminals
The battery terminals should not show movement when you (gently) wiggle the wires.
While not very common, battery terminals may come loose from hard impacts or fatigue when a battery loose battery moves around in the battery compartment or tray.
Loose or damaged battery terminals are dangerous and can cause a short circuit, which can cause the battery to explode.
9. Discolored Battery Fluid
On a conventional serviceable lead-acid battery with removable battery caps, you can inspect the condition of the battery fluid.
Caution: Always wear eye protection when working on a battery.
If the fluid levels are low, you should top off with distilled water so that the level is between the max and min mark before charging.
The battery acid should be clear and colorless. A dark or brownish fluid in one or more cells indicates a bad battery and renders the battery useless.
Why Do ATV Batteries Go Bad?
While some ATV batteries go bad from overcharging, physical damage, high temperatures, or short circuits, the number one cause is an internal chemical process known as sulfation.
When a battery discharges, the chemical reaction that happens inside the battery creates a by-product known as sulfate (salts of sulfuric acid). The build-up of sulfate salts on the lead plates is called battery sulfation.
Charging the battery naturally reverses the sulfation process by turning most sulfate salts or crystals back into electrolytes (battery acid).
But some sulfate salt crystals remain on the lead plates, and as the battery ages, they begin to build up.
The battery gradually loses some of its capacity (its potential to reach a full charge) as the sulfate crystals increase in size and harden on the lead plates. The sulfation also increases the battery rate of self-discharge.
Sulfation can be kept at a minimum by ensuring the battery stays at full charge most of the time.
The sulfation process accelerates when a battery sits at a drained or low state of charge for extended periods, such as through winter storage.
That is why your best hedge against a bad battery is to leave it on a maintenance charge throughout winter storage and to top it off now and then through the riding season.
When a battery has become sulfated to a point where it can no longer hold a charge, your only option is to get a replacement battery.
How to Test if Your ATV Battery Is Bad
What do you do if you are still unsure whether your battery has gone bad or still has some life left?
If you have access to a standard multimeter, you can perform a so-called load test that indicates the battery’s remaining capacity.
Learn how to do this simple test and more in your guide on how to test an ATV battery.
What Happens When a Four-Wheeler Battery Dies?
A battery that doesn’t hold enough power to start the ATV is often called a “dead” battery. When an ATV battery drops below the recommended minimum operating voltage, it can no longer power the electric starter, and the engine will not start. However, the bike will run as usual if you get it to start.
When an ATV battery begins to die, you start seeing see signs like
- Dim headlights.
- Slow engine cranking and hard starts.
- Clicking sound and no engine cranking when you activate the starter.
- No lights in the dash.
- The battery warning light turns on.
You can often revive a dead battery if it doesn’t sit in a discharged state for too long.
Can an ATV Run With a Bad Battery?
An ATV will run and operate normally even if the battery is bad. The ATVs charging system provides enough electricity for crucial components such as the ignition, power steering, and lights to work normally. In a pinch, you can jump-start the bike and ride back home if you accidentally left the headlights on through the night on your camping trip.