what charges the battery on a four wheeler

The stator generates AC voltage, then the rectifier/regulator converts it to DC and regulates it to around 13.5-14.5V to charge the battery. If you're only seeing 12.2V at idle, that's weak. Could be a bad regulator or a stator with shorted windings. I'd check AC voltage from the stator first—should be 20-30V AC at idle. If that's good, then the regulator is likely shot.

I had the same issue on my Polaris. Turned out the ground wire from the regulator was corroded. Cleaned it up and voltage jumped to 14V. Also check the battery connections—loose or dirty terminals can mess up charging. Don't just throw parts at it.

Actually, a low voltage at idle might be normal if the engine isn't spinning fast enough. Rev it to 3000-4000 RPM and measure again. My Suzuki needs about 3000 RPM before the stator puts out enough to charge. If still low at higher RPM, then start testing components.

On my Rancher, the stator went bad after water got in during a mud ride. Unplug the connector from the regulator and measure resistance between each of the three stator wires (if it's three-phase). Should be around 0.5-1.0 ohm. Also check for shorts to ground. Found mine open after a flooded crossing.

I disagree a bit with the first reply. Most ATVs don't charge much at idle—the charging system is designed to work at riding RPMs. So don't panic if your idle voltage is 12.2V. But if it's below 13V at 3000 RPM, that's a problem. I'd also check the battery itself—could be sulfated from sitting.

Before diving into electrical tests, load test the battery. A bad cell will show decent voltage but won't hold charge. Auto parts stores often do free tests. I had a battery that read 12.6V but dropped to 10V under load. Replaced it and the charging system was fine.

On my old Bombardier, the regulator was mounted near the exhaust and overheated, causing intermittent charging. I moved it to a cooler spot and it worked better. Check that your regulator has good airflow and isn't caked with mud. That's a common overlooked issue.

Make sure you're using a multimeter set to DC voltage. Some people mistake AC readings. Also, some ATVs have a separate charging coil for the battery vs the lights. If your headlights are dim, it might be a coil issue. What year and model exactly?

I just went through this on a 2004 Kodiak. Turned out the rectifier had a blown diode. You can test diodes with a multimeter in diode mode. Should have one-way conduction. If it passes both ways, it's shorted. Bought a cheap aftermarket regulator and it's been fine for two seasons.

Be careful with aftermarket regulators—some cheap ones don't regulate well and can overcharge. I toasted a battery that way. Stick with OEM or reputable brands like Rick's Electric. Also check the wiring harness for rubs or breaks near the frame. A broken wire will give intermittent charging.

If you're not comfortable testing with a multimeter, you can also do a simple test: start the ATV, disconnect the battery positive while running. If it dies, the stator or regulator is bad. But that's old-school and risky on modern EFI machines. Better to get a meter.

I had a loose connector at the stator. Pushed it in and problem solved. The connector was hidden under the frame. So check all plug connections. Sometimes a little dielectric grease helps keep corrosion out. Also check the fuse—a blown charging fuse will stop everything.

On the topic of mods, does adding a winch or lights drain the battery faster? Yes, if the stator can't keep up. My stock stator only puts out 200W, and I added a winch and light bar. Had to upgrade to a higher output stator. Look up your machine's charging capacity.

Before buying parts, you can also check if the battery is being charged by the alternator or generator? It's a permanent magnet alternator on most ATVs. No brushes or belts. So if the magnets are weak, stator output drops. Rare, but possible on older machines.

One thing nobody mentioned: the voltage regulator might be grounded through its mounting bolts. If those bolts are rusty or painted, there's no ground. Clean the mounting surface and add a separate ground wire. That fixed my charging issue instantly.

Second that on the ground. I spent a week chasing a charging problem on a Sportsman only to find the regulator mount was painted. Sanded it down, slapped some conductive grease, and boom—14.2V at idle. Always check grounds first.

I had a similar problem and it was the battery itself. The new battery I bought was defective. So if you replaced the battery recently, that might be the culprit. Try jumping from a known good battery and see if voltage climbs when revved.

On a budget? You can buy a cheap oscilloscope or use a multimeter with frequency setting to check stator output. But honestly, a simple resistance check and AC voltage test will find 90% of issues. Don't overthink it.

I half agree with the first reply—12.2V at idle could be fine, but if it doesn't climb above 13V at 3000 RPM, something's wrong. Also check the battery's resting voltage after sitting overnight. If it's below 12.4V, it's either not charging or the battery is going bad.

last advice: buy a service manual for your specific model. Wiring diagrams and test specs save hours. I wasted money on a stator I didn't need because I guessed wrong. The manual told me exactly what voltages to expect at each connector. Best $30 I ever spent.