How Does a UTV Charge the Battery?

One of the most common problems with UTVs and offroad vehicles that would keep them from starting is a battery issue. Over the years my wife and I have tried out a few different types of off-road vehicles and learned very quickly that one of the main maintenance issues is keeping the battery charged.

So How does a UTV charge the battery?

A UTV charges the battery using a system consisting of :

  • A Stator
  • A Rotor
  • And a Regulator Rectifier

It is basically a set of magnets moving past a copper wire array creating an electromagnetic field that generates electricity.

How the Stator/Rotor works:

The stator and rotor work similarly to an alternator except that they are built into the inside of the engine casing. The stator is disc-shaped with iron core outer spokes that are wrapped in copper wire and is stationary.

The rotor is an array of magnets built-in to the flywheel. As the engine crankshaft turns the flywheel, the magnets of the rotor spin around the stator’s spokes of copper wire coils and generate an electric alternating current.

Regulator Rectifier:

That alternating current (AC voltage) is pushed to a Regulator Rectifier. The rectifier converts the AC energy into direct current (DC Voltage) so that it can power your battery and other electronic components like your lights, ignition, and other electronics. The regulator keeps the DC voltage within its required range of 13.8-14.5 volts for safe operation.

Higher RPM’s Charge: 

Because the stator (or ‘magneto system’ as it’s sometimes referred to) is in a 1:1 ratio with the crankshaft, the charging system does not do a very good job at lower RPMs like at idle. Your UTV isn’t charging/maintaining the battery while it’s just sitting there running, only while you are out driving getting the RPMs higher.

Stator instead of Alternator: 

The alternator in your car or truck works in a different ratio than 1:1 because it uses pulleys and belts which give it the ability to push out a lot more electricity. Alternators need airflow and do not operate well with water or debris so that’s why your UTV has a fully encased stator instead.

Battery Drainage:

 Almost any battery that is left plugged into its intended device (even if it’s not being used) will slowly drain over time. Since you use your car/truck on a regular basis, it’s constantly charging itself but as most UTV owners park their Side by Sides for long periods of time the battery is slowly drained.

Check out our recommend trickle charging solutions further down this article.

Do Side by Sides/UTVs Have Alternators?

Most UTVs do not have an alternator as they take advantage of the stator system described above but there is always that one kid in class that just doesn’t fit in.

Enter the Roxor by Mahindra. This Jeep-looking vehicle has multiple reasons that make me scratch my head and ask: “How is this still a side by side?” but one of the main ones is the power plant

Long story short, to be classified as a UTV or Side by Side the engine has to be less than a 1000CCs and the Roxor is using a four-cylinder, 2500cc, turbocharged diesel. Because of this more automotive-style power plant, the Roxor has an alternator. Okay, so there’s not just one odd one out as a few of the diesel-option UTVs are also using alternators.

I believe that the reason for the stator vs the alternator in most UTVs is that Side by Sides adapt a lot of technology from quads and motorcycles as opposed to sand rails or 4x4s and motorcycle-style engines have stators where most larger four-wheel drives have alternators.

Examples of UTV’s with Alternators:

  • Mahindra Roxor Turbo Diesel 
  • John Deere GATOR 825i Gas & UTV Gator Xuv 855D Diesel
  • Kubota RTV-X900, RTV-X1100C, RTV-X1120, RTV-X1140 Diesel 
  • Caterpillar CUV102D & CUV105D  Diesel 

To replace an alternator can be about $70+, but if you want to convert from a stator to an alternator, it can cost around $600 – $2,300 for an alternator kit depending on your UTV Make and Model,

If you have a Polaris RZR and want an alternator there are a couple of companies that make an alternator add-on kit for $2,300. Here is a link to one such kit on Amazon.

Side by Side Battery Charger

I highly recommend getting a trickle charger for your UTV during the offseason. Anytime you know you’re going to park your side by side for 30 days or longer you need to put it on a maintenance charge.

No matter what charger you use, you don’t want to exceed a 2 amp charge. Most automotive battery chargers have a 2/10/50 setting selector so you could just use what you may already have in the garage.

The ideal setup is a battery charger that puts out a small number of amps, is always connected via a quick connect harness, and has built-in electronics that charge the battery only when it is necessary avoiding overcharge.

I recommend the Battery Tender Junior, click here to go see one on Amazon.

Another great option would be the NOCO Genius G3500.

Installing a Second Battery on a UTV

So you have a UTV and don’t want just the stock feel? You’re wanting to add a few light bars, a winch, and a stereo that shakes the ground beneath you? Well, I’m guessing after about one aftermarket install you will start to notice the drain on your electrical system.

Stators just don’t put out as much electricity as alternators, period. So one way to get around battery drain from too many accessories being used (especially while parked) is to install a second battery.

The battery itself will be in the $50 – $200 range and you will want to mount it near the existing primary battery. I recommend getting a match to your existing battery, preferably AGM deep cycle and not lead-acid. (In the event of a rollover, I don’t want a lead-acid battery in my UTV.) A great option for both batteries would be the Odyssey PC925 at around $185. Click here to get one on Amazon.

To really get the most out of having two batteries you will want to install a smart battery isolator. A company called TrueAm creates smart isolators that act as a bridge between the two batteries and your UTV.

When the UTV is running and the charging system reaches 13.4 volts the True Smart Battery Isolator kicks in and connects the two batteries so that they can both charge together. The True unit has a blue LED that will light up to show this is happening.

When the voltage drops below 12.9 volts the True isolator separates the two batteries preventing your primary ‘start’ battery from being drained by accessories powered by the second battery.

TrueAm sells a full kit that includes the smart isolator, all necessary install cables, and a voltmeter gauge that shows the current voltage of both batteries for $130. Check it out on Amazon by clicking here.

Another dual battery option is a kit from a company called Genesis Offroad. Their kit includes everything you need including a battery, a smart isolator, and all the necessary wiring for $339. The requirements of this kit are that you have a Polaris RZR 900 or 1000 that is 2014 or newer and you already have a non-stock battery like an Odyssey PC925 or the XS Power PS550.

If you need to add switches for all those new electrical accessories and also want somewhere to install that new voltmeter into your dash, then you may want to consider adding a switch panel like this one also on Amazon for $40. 

How to Jump a UTV/RZR Battery

The first rule of UTV battery jumping is we do not jump from a car or truck. And the second rule of UTV battery jumping is that we do NOT use a car or truck to jump from. It’s that important… so don’t do it.

Using a regular vehicle for the jump could really mess up the UTVs battery and/or electrical system. (If you have absolutely no other choice than to use a car, then follow the instructions below but do NOT start the car which is step 6)

Two major safety notes:

  • Creating sparks at a battery post can cause an explosion. Batteries not working properly can emit dangerous hydrogen gas.
  • During the jumper cable installation, make sure you do not let the cables touch each other as this creates a short circuit and can damage the battery. Also, the sparks can ignite any flammable sources.

Steps for Jump-Starting a UTV from Another UTV/ATV

  1. Park the good battery vehicle as close as possible to make the connection.
  2. Hook a red jumper cable to the dead batteries positive terminal.
  3. Hook the other side of that red jumper cable to the good batteries positive terminal.
  4. Hook the black jumper cable to the good batteries negative terminal.
  5. Now attach the other end of that black jumper cable to a good grounding point. (do not hook it to the dead batteries negative post as sparks could cause a hydrogen gas explosion)
  6. Start the engine of the good battery vehicle and get the RPMs high enough for the charging system to provide power.
  7. Now start the dead battery UTV.
  8. Unhook the cables in reverse order for safety. (Step 5, then 4,3,2)

A very safe and somewhat convenient option is a portable jump starter.

Not that different from a portable power bank for your cell phone, a portable jump starter is just a small battery that comes with accessories like cables with alligator clips to hook up to a dead battery and other optional cables to charge smaller devices that utilize USB cables.

Click here for a great jump starter by NOCO for $100 that can jump-start a battery 20 times on a single charge.

Can’t reach the battery terminals very easily for the emergency jump start? A company called UTV Stereo has a jump post that is like an extension cord for your battery terminals. Check it out here.

If a killer sound system is your thing I highly recommend you check out UTV Stereo’s website as that is their specialty.

How to Test a UTV Charging System

First, check the battery by hooking up a multimeter to it to ensure that you’re between 12.5 and 13.5 volts.

You can do a load test by simply hooking up a load tester to the terminals to simulate a load on the battery. With this test, you don’t want the battery to drop below 10 volts. If the battery can’t handle a load, it’s probably time to replace it.

Another way to do this test would be to hook up the multimeter to the battery and while checking voltage start your UTV. Make sure you watch the display on the multimeter while it’s cranking to see what the lowest voltage it drops to is and again you don’t want it to drop to 10 volts or lower.

To perform a system charging test leave your multimeter hooked up to the battery and start your UTV. You will have to rev the engine up to 5,000 RPMs and at that point, the meter should read between 13.8 volts and 15 volts DC.

If the volts don’t increase very much on this test it’s okay, it just means the rectifier regulator is doing its job regulating the amount of voltage put back into the battery.

Another good test of your UTV’s electrical system is called a parasitic amperage draw. It measures the amount of current that is leaving the battery when the machine is in the ‘off’ state.

To perform this test you have to unhook your battery’s negative cable and put your multimeter ‘in series’ by connecting the leads from the multimeter to the black cable you just unhooked from the negative terminal and the other multimeter lead to the negative terminal of the battery. If your eyes have just gone crossed, see the picture below.

The positive lead on your multimeter needs to be connected to the fused side of the multimeter and switch the meter to measure amps DC. With the UTV off you don’t want to be registering more than 8 to 10 milliamps.

If you are having larger draw numbers then you can start to unhook any potential aftermarket accessories or just remove their fuses to see what may be causing that draw.

A word of caution, while you have your multimeter hooked up in series to your UTV, do NOT start the UTV or it will damage the multimeter.

Charging Tips

  • Make sure battery connections are tight.
  • Keep the terminals clean with a baking soda and water mix.
  • Keep the battery on a trickle or maintenance charger.
  • Don’t charge using any more than 2 amps

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