Trying to identify the reason why your ATV battery keeps draining can be quite frustrating. This guide will tell you how to troubleshoot the issue.

You may be out riding all day and everything seems to be working correctly. Then you park the ATV for the night, and in the next morning, the battery is completely dead. When you turn the key, you get no reaction what so ever. Except maybe a clicking sound from the starter.

This behavior is very common when you have an ATV battery that keeps going dead.

But depending on what is causing your battery drainage, your bike may behave differently. It can lose all of its power in just a matter of hours. Or you may even be experiencing a battery that is being drained when you are out riding.

In the latter case, there is usually a completely different cause for your problems than with the first. I will cover both situations in this post.

Thankfully there is a lot of relatively straightforward troubleshooting you can perform yourself to identify and even fix whatever is causing you problems.

Sometimes the error is cheap and easy to fix. Other times it can be more of a challenge and require purchasing some parts. I recommend going through this list of common issues before you start throwing money at the ATV like buying a new battery or other parts.

Where to begin?

To be able to isolate what is causing the problems you need to observe how the bike is behaving in different situations. When does it drain? When you are riding or when it is just sitting in storage? How long does it take for it to drain?

By doing this you can quickly rule out a lot of the possible causes, and you won’t need to waste time and money on the wrong things.

Begin with the step below that matches your bikes behavior the best. Under each listed cause, I describe how the ATV will be behaving, how to troubleshoot and possibly how to fix the issue.

Sometimes you will be able to locate the drain right away, and other times it takes a couple of tries before you succeed.

1. Bad or old battery – not holding a charge even when not connected to the ATV

All batteries will die at some point. Some sooner than others, depending on the type of battery,  how it’s used and how it’s maintained.

Because of the small size and rough handling an ATV battery needs to endure, it will generally not last as long as a car battery.

To test if your battery holds a charge, simply disconnect both terminals and fully charge the battery. Use a multimeter to measure the voltage.

If it still loses its charge over a day or two, you likely have a bad battery. Notice that this behavior may be due to internal sulfation, which sometimes can be fixed. More on that further down.

If the battery does not discharge when left disconnected, the issue is likely not the battery itself. If so, it’s more likely something on the ATV that is causing it to drain or causing it not to charge as it is supposed to.

Load test

A better way to test if your battery is bad is by performing a so-called load test.

Ideally, you would want a load-tester to perform this test, but you can also perform it if you have a multimeter with a min/max function. This will not give accurate results but it should give you a decent clue.

This test tells you if the battery can hold a high enough voltage level under heavy load. 9.6 volts is the magic number here. If your battery drops below this level under heavy load it needs replacing.

  1. Start by charging the battery. To perform this test you want to make sure the open circuit voltage available at the battery is above 12.4V (at least 75% charged). To check this you simply put your meter to DC voltage setting and connect the leads to the battery. Red to the negative terminal and black to the negative.If you can’t reach above 12.4 volts by charging, your battery is likely too sulfated. If you can’t get it to charge over 10.5 volts you likely have a bad cell.

    Normal voltage reading with the engine turned off.

  2. Push the min/max button to start recording the voltage.
  3. Push the starter on the ATV. This will draw a lot of current from the battery for a short period of time. It doesn’t matter whether the bike starts or not.
  4. Turn off the bike and have a look at your readings. If your lower reading is below 9.6 volts your battery is bad. It does no longer hold a sufficient capacity.

2. Low fluid levels in the battery

If your battery is of the lead-acid type (not gel batteries) you want to check that the fluid levels are correct. This is a quick and easy job that should be done early on in your testing and definitely before you discard the battery.

When the electrolyte levels are too low, the battery will not function as it should and may not take, or hold a charge. This will be true whether the bike is being used or if it is parked.

Be aware that this tip only applies if your battery has removable covers over the battery cell-ports. Batteries that do not feature this possibility are usually labeled maintenance free and simply needs to be replaced when they stop working well.

Do not try to open a battery that is not made to be opened!

  • Before you remove the covers, I recommend you clean the battery thoroughly by wiping with a rag sprayed with an ammonia-based window cleaner. You do not want any debris falling into the ports as this may reduce the capacity or even damage the battery.
  • After cleaning and drying the top of the battery you can use a screwdriver to pry open the covers or unscrew them, depending on what type of covers you have.
  • Use a flashlight to inspect each individual cell. The plates need to be covered with electrolyte and the levels should be equal in each cell.
  • Top-off with distilled water until you reach the maximum safe level, which is when the fluid is barely touching the bottom of the filler tubes.
  • If the plates have been exposed to air, the exposed area will likely be damaged by severe sulfation. But often times they can be brought back to life, although with a slightly reduced capacity, simply by making sure fluid levels are correct.
  • If the levels are low, you should check if the battery has any visible leaks as this will require the battery to be replaced.
  • When the levels are correct you should recharge the battery and check that it holds its charge.

3. Defect new battery

Even new batteries can be bad.

If you’ve done the tests and concluded that all systems are working properly and that your problems must be caused by an old or bad battery that cannot be revived, you are left with having to purchase a new battery.

But from time to time you may find that the issue keeps persisting even right away or shortly after you’ve replaced the old battery with a new one.

This may indicate that you have not really identified the actual cause of your issues, but it may also be that you’ve received a faulty battery.

Even new batteries may short out, leaving them useless. To test this, perform a load test on the new battery as described in the step for old batteries above.

Your dealer should also be able to help you do this test to rule out any issues with the newly purchased battery.

When it comes to batteries the whole “you get what you pay for” is usually very true. Especially for ATV batteries that need to handle a lot of abuse from bouncing around, risking damage to the internal components. Get a good quality battery to save yourself for a lot of frustrations.

Make sure the ratings on your new battery is as good or better than the original battery. Compare amp hour ratings and cold cranking amps. You are likely able to find a better capacity battery of the same size as the original battery.

4. A loose or corroded connection of the ground cable

Another possible issue witch is quick and easy to address will be to make sure the main ground cable that goes from the battery to the frame of the bike is well attached in both ends, is not damaged and that the terminals are not attacked by corrosion.

A bad or corroded connected connection will prevent the charging system from topping off the battery when you are riding and may even cause a small drain of the battery on its own.

Simply removing any corrosion from the terminal or fastening any loose connections may be adequate to fix this issue.

So make sure your grounding is in good health before you invest time and money in other possible issues.

5. The battery is sulfated

As mentioned earlier, if your charger tells you that your battery is fully charged, but you don’t get a reading of 12.4 volts or above when you test with a volt-meter, your battery is likely sulfated.

When your battery is sulfated it not only loses its ability to hold a full charge, it also leads to self-discharging quicker than it should. The sulfation may also give a false voltage reading, tricking the charger to mistakenly believing the battery is fully charged when it’s actually not.

I won’t go into the details, but sulfation is a natural by-product from the chemical process going on inside an acid-lead battery when it’s discharging. Normally the process will be reversed when the battery gets charged again, where the sulfation is transformed back into electrolyte.

But under some circumstances, the sulfation will harden and build-up on the plates inside the battery. This hardened sulfation will not be reversed into electrolyte under normal charging.

You can never prevent sulfation completely, but it will happen prematurely when:

  • The battery sits too long between charges. It’s a good idea to snap on a battery tender if it’s more than a few days between every time you use your ATV.

    The Ctek Multi XS 3600 is a cheap charger/tender that works well.

  • The battery is not being charged to full capacity whenever it’s being charged. This is common on vehicles that use load-hungry accessories like a winch on an ATV, where the charging system cannot keep up. A charging system not functioning properly will have the same effect on the battery. Periodically you should use a charger to attain full saturation. This may take as much as 16 hours.
  • Electrolyte levels are low, make sure they are topped off to correct levels as the plates sulfate when being exposed to air.
  • The battery is being stored for longer periods of time with only a low or partial charge. Always store the battery fully charged, and preferably keep it connected to a battery tender to maintain a constant energy input.
  • The battery is left drained/discharged, even only for a few days.

Often times a battery with hardened sulfate can be salvaged by performing a specific charging cycle. This will be described in a post of its own later on.

6. Something is drawing a current and draining the battery overnight

If your battery is in good health and holds it’s charge when not connected to the ATV, but it’s being drained overnight when connected and the ATV is just sitting with everything in off-position, it means that something is drawing current.

This is known as “parasitic amperage draw”.

You will need to do some testing to diagnose and locate the circuit that is responsible for the draining of your battery.

The test is called a parasitic drain test and is something any home mechanic should learn how to perform.

Notice that checking voltage and checking for amps are two completely different things and requires different testing procedures. Mistaking a voltage reading for the amperage draw is a common rookie mistake that people do.

While doing this test do not make the same mistake as I one time did by sending a high current directly through the meter.

Doing something foolish like starting the ATV or even turning on the lights when the meter is connected will send a current much greater than it is designed to handle through the meter. This will in best case blow a fuse or may even fry your device.

Before we go into the actual testing you should know that most modern ATVs today will always have very small amperage draw, even when the key is turned off. This is due to electronics that always needs some power to maintain different memory functions like the clock in your display, the memory of your Ecu and so on.

The maximum amperage draw with the key turned off should be found in your specific bikes user manual, but it should generally be less than about 50mA (0.05A).

This draw is perfectly normal and is irrelevant to the issue that is causing your battery to drain overnight.

To perform the test you will need a multimeter with the possibility to measure amperage draw. For this test to work, the meter should be able to read draw of at least 2-3A. Most multimeters are rated with a 10A or a 20 A capacity.

First, you will need to determine whether you have a parasitic amperage draw or not.

  1. Start with a fully charged battery.
    It should read at least 12.4 volts. Measure this by putting your multimeter in the 20 V DC section of the scale. If you have an auto-ranging meter just put the meter in V. With the bike turned off, put the black lead into the COM port and to the negative terminal of your battery, and the red lead to the voltage port and to the positive terminal. If the voltage is too low, fully charge the battery and let it sit for at least 30 mins before you move on.
  2. Make sure nothing is turned on.
    The key should be in the off position. Wait for 1-2 minutes after you turned off the key.
    On some bikes, the ECU needs this time to go into “sleep mode”.
  3. Disconnect the negative terminal/cable from the battery.
    This test will actually work just as fine whether you choose to disconnect the negative or the positive cable from the battery. But with the positive cable disconnected you risk shorting it against anything metal near the battery. This may in the worst case lead to serious damage to your bikes electronics. That’s why I recommend that you perform this test by disconnecting the negative cable.
  4. Setup your multimeter for the test.
    The black lead/probe should be in the COM port, and the red lead/probe should be in the amp port. This port will be marked with either 10A or 20A, depending on your meters rated capacity. Initially, do not use the mA port as this may damage your meter when performing this test. Turn the wheel on your meter to the DC 10A/20A position.

    Proper settings for measuring amperage draw on the multimeter.

  5. Connect the red probe to the disconnected negative battery cable.
  6. Connect the black probe to the negative battery post.
    This will use the multimeter to complete the circuit and measure how many amps are going through the circuit.
  7. Take note of what readings you get.
    The reading in the display of your multimeter is the amperage being drawn from your battery. This value should be under the rated maximum draw of about 0.05A. If you are over this value you have a parasitic amperage draw. If so, you generally will have a reading of at least 1A. If you get no reading, try switching the red lead to the mA port and measure again. Any large parasitic draw should be clearly visible.

If you did measure a parasitic amperage draw you should now continue with the steps underneath to diagnose what circuit and further what specific device that is responsible for your problems.

  1. Keep the multimeter connected as described above
  2. Disconnect any accessories that can be operated even when the key is off
    If your ATV is stock, there isn’t anything on your machine that should draw current when your key is off, except the memory functions mentioned above. If you have installed any accessories that will operate even when the key is off, you should disconnect these first to see if this eliminates the draw. This could be cell-phone chargers, heated grips, winch, GPS etc. If your winch has a wireless remote, look for an on/off switch. Because if it’s left on it will continue to search for a signal until the battery is drained even when the bike is not in use. Use the multimeter as described above to see if the draw disappears when the accessory is disconnected. If not, move on to the next step.
  3. Locate the ATVs fuse panel
    Notice that some ATVs have more than one panel. You want to locate all of them.

    Front fuse panel on a Polaris Sportsman XP 1000

  4. Systematically pull out fuses one by one
    This should be done until you see the amperage draw reading in you multimeter drop down to under the specified maximum value. This will be the circuit where your issue is located.
  5. Partial drop
    If you have more than one issue drawing current from your battery you may experience just a partial drop when pulling one fuse. For example, your reading may drop down from 2A to 1A when you pull a specific fuse, and not down to under 0.05A. This indicates that you have more than one issue on your bike. Leave this fuse out and continue pulling and putting back fuses one by one until you locate the other circuit drawing a current.
  6. Also, pull out relays in the same matter.
    If the readings did not drop under the rated maximum levels by pulling fuses you should also try pulling relays one by one. A defect relay may fail to disengage and may cause a constant drain.
  7. Reconnect the negative terminal to the battery
  8. Use the leads of the multimeter to jump the fuse terminals where you’ve found you have an issue.
    The fuse should be left removed. You should get about the same reading as you did when you measured at the battery.
  9. Take a look at your user manuals wiring diagram to identify which devices are protected by this specific fuse.
    These are the devices you need to inspect further. If you don’t have the wiring diagram available, you can try starting the bike and test witch functions that are not working with the fuse removed.
  10. Disconnect each device on the circuit, one by one. Check with the meter. When the amperage draw drops significantly, you have located your problem.
  11. Identify the problem.
    The fault can be in the device itself. But you should also take a look at the wiring, connections, and switches. Are any connections bad, or do you notice any wear or damage to the wiring, creating an electric bleed that will draw a current? Examine closely where the wires are secured to the frame or where it may be rubbing against other components. Is your 12V accessory plug full of mud? This would cause a drain, you’d be surprised how often this happens.
  12. If you didn’t find the cause of your amperage draw by pulling fuses or relays, the draw can be caused by a short in something that is wired directly.
    Try disconnecting the starter or voltage regulator to see if this resolves your problem. Also look for powered cables that have come loose enabling them to bump against the frame when riding, creating a short.

7. Charging system not working properly – bad stator or voltage regulator

When the engine is running, the ATV should get all the electricity it needs to operate properly from the bikes charging system. There should be no need to drain power from the battery.

The stator should generate enough power to not only operate all of the electronic functions of the bike, but there should also be enough of a surplus to charge the battery that has been drained a bit from starting the bike.

But sometimes these systems go bad. There are some ways you can test if your bikes stator is functioning as it should.

Reading current voltage using the bikes Diagnostic mode

To begin with, you can enter your bikes “diagnostic mode” if it has one, to get a reading of the current voltage. Consult your owners manual on how to do this.

If your bike doesn’t have this feature you can achieve the same readings by manually measuring the voltage on the battery with a multimeter.

Start the bike when the engine is cold. It should be minimum 13,5V when the bike is idling and rise to 14-14,5V when you rev the engine a little.

Then drive the bike for some minutes to heat up the engine and test again. Your readings should not change from your cold engine readings.

Low or no readings could indicate a bad stator. High readings could indicate a bad voltage regulator.

But before you conclude on what your issue is and start buying parts, I recommend you do some further testing.

Testing the performance of the stator and voltage regulator with a multimeter

This method is written based on a Polaris XP ATVs but should work fine on any ATV Note that some of the components may have a slightly different location and appearance.

This test does, however, require some more technical experience than the others in this article. So if your comfort level has been reached just by adjusting the air pressure in the tires or changing a light bulb, you should probably ask a friend for some help with this one.

  1. Start with the bike turned off.
  2. Remove the side cover where the stator is located, usually on the left side.
  3. There should be three yellow cables coming out from the engine in this area that goes up to the ECU, located in front on top of the radiator. The cables may be in different colors, but yellow is most common. If you are not sure, see if you can get a hold of the wiring diagram for your specific bike.
  4. The wires will run into one flat plug on the side of the motor. Unplug this connection.

    Yellow cables coming from the stator on a Polaris.

  5. With the bike still off, measure the ohms between all 3 wires. Measure between wire 1 and 2, then 1 and 3 and finally between 2 and 3.You should read no more than 3 ohms of resistance.
  6. Next, you want to test all 3 wires for continuity to ground. Many multimeters have this function, or you can use a continuity tester with a test light. None of the cables should be in continuity with the ground, so you should not get any reading (no beep) while performing this test.
  7. Then you should start the bike to let it warm up to normal operating temperature. Repeat the test in step 6. If all the numbers remain the same as your previous reading then your stator is likely working as it should.
  8. Next, it’s the voltage regulators turn. Plug everything back in and start the engine. There should be a red and a black cable coming out of the regulator. Check the voltage readings at the red cable coming out of the voltage regulator. You should get a reading of about 14-14,5 volts.
  9. If you do get a reading of 14-14,5 volts, go to the battery and test the voltage there. Ideally, you should get the same reading as you did in step 8. If not you have a broken wire or a bad connection at either end of the cable.

A bad voltage regulator or ECM on EFI bikes

If you performed the above test (step 8) and you get a reading above 14-14,5V at the battery, your bike is overcharging. This usually indicates that your voltage regulator is defected and needs replacing.

But often the voltage regulator breaks because of a faulty stator. If the testing indicates that the stator is working fine, you can start by replacing the voltage regulator.

Regular voltage regulators you can usually find relatively cheap on eBay. ECM’s are a bit more pricey. It’s worth checking if there is issued a recall on your bike as many early ECM were known to fail and were replaced for free by the manufacturer.

Overcharging is not good for your bike and can fry different electrical components and ruin your battery by boiling the electrolyte fluids in it.

If you’ve been riding with over-charging for some time your battery may already be boiled dry and this may be why the battery is being drained.

After fixing your charging system you could try reviving the battery by adding distilled water up to correct levels, but there is no guarantee this will work. If it doesn’t, you need to also get a new battery.

8. When riding you use more electricity than the charging system can deliver

Even if you’ve gone through all of the steps in this guide and have not found anything that indicates that something is wrong, you still may experience that the battery drains while you are riding.

This cause is actually more common than you may think, especially if you use a lot of power-hungry accessories like a winch, a GPS-navigation or a phone charger.

The purpose of the battery on an ATV is to power the starter motor when you start the bike, and to supply the needed electricity for functions that are being used when the engine is not running. On ATVs, this generally boils down to anything that has a memory function, or if you have connected a phone charger, GPS or maybe a booming sound system to your bike.

When the engine is running, all of the electric power the bike needs is delivered from the stator. But when you use more electricity than the charging system can deliver, the bike is forced to use from the power being stored in the battery.

The charging system on an ATV has nowhere near the power output you have on a car. This is because a car uses a belt-driven alternator, while an ATV uses a much less powerful stator system.

Alternators are not used on ATVs because they have more moving parts leaving them more prone to being damaged from the dirt, water and rough handling it will have to handle in a quad. The stator is protected by being embedded in the engine itself.

On early ATV’s this was never an issue, as they did not need much electricity to function properly. But over the years the bikes have been fitted with more and more power consuming features and electronics like power steering, electronic engine controls, displays and navigation systems. All of which needs it’s share of electricity to function properly. The manufacturers have done a great job of developing the stator system so it will perform optimally. But even so, it sometimes cannot deliver enough power to prevent the battery from being drained even when riding.

9. Battery draining when plowing

This is a specific example of using more power than the charging system can handle. I gave this a heading of its own because it is the most common reason to why the battery is being drained while riding.

However, with just a few simple adjustments to how you ride you may be able to eliminate this issue altogether.

Plowing requires you to raise and lower the plow repeatedly by using the winch. And the winch is as you may already know one of the most power-hungry accessories you may have on an ATV. It will drain your battery in no time if used excessively over a short period of time.

Here are a few tips you can implement to prevent your battery from draining when plowing:

  • Always plow in low range gear if your bike has this option. This will increase the RPM’s (revolutions per minute) of your engine compared to driving at the same speed in the high gear range. Higher RPM’s means the flywheel that is generating your electric power spins faster and gives a higher output. This keeps the voltage regulator operating at full capacity, reducing the need to use power from the battery to a minimum. As an added bonus riding in lower gears will decrease wear on your ATVs drive belt.
  • Make sure your battery is in good shape and not too old. When the battery gets older it loses some of its capacity. And when plowing you need all the capacity you can get. Consider replacing it with a new one if it’s starting to age. Get one with as high amperage hours as you can fit.
  • Get a battery tender to top off your battery between each time you plow. This is a cheap and easy way to make sure the bike is in top shape and ready to go every time you need it.
  • If you still need more power, consider adding a second battery to power the plow. This requires you to charge the battery between each time you plow as the bikes charging system is not designed to handle this amount of amperage hours.
  • Reduce the bikes overall electric power consumption by replacing headlights and taillights with LED bulbs as this draws less current. Every little bit helps.
  • This is a more fun alternative to using a battery tender: Go for winter rides between each time you ride to give the bike a chance to recharge the battery on its own. For people who use their bikes for casual riding throughout the winter, battery-drainage when plowing is usually not a problem. It is usually those who only start the bike, plow and park the bike again who eventually run into problems.

10. Driving in extremely cold conditions

The performance of lead-acid batteries will suffer if you ride in extreme temperatures. In freezing weather the capacity will drop by about 20%, end when you hit -30 Celcius (-22 Fahrenheit) it will be down by about 50%. So one may say the temperature “drains” the battery even before you start using it.