I bought my brother's 2004 Sportsman 500 HO and he said the only issue was a "battery drain" problem that he couldn't figure out. The machine is otherwise in mint condition, well cared for with very low miles. During his ownership, it would frequently sit for several months at a time without being ridden. He replaced the battery once about 2 years ago.

I keep the battery on a tender and it will usually start right up on the first try. However, if it sits for even 2 days (without the tender hooked up), the battery won't hold enough charge to start the ATV. In addition, I noticed when I was using my ATV mounted sprayer that the battery light would come on after a few minutes of use. I checked all the battery connections and all the connections to the starter solenoid (including the frame ground) and everything looked good.

I have yet to load test the battery but I do know that when my brother replaced the battery 2 years, it didn't fix the problem.

Any suggestions?

 

Check while idling that the battery is receiving 14 volts with a volt meter. If not could have a bad regulator/rectifier draining the battery down,loose wiring at the regulator Or depending on which model Sportsman 500 you have, some were equipped with an ecm instead of the regulator and were under a recall. Easy to see which one you have. Reg/rectifiers at the front of the atv close to the radiator under the front panel. The ecm is a finned module mounted close to the ignition coil.Even replacements can go out. Controls charging and fan operation. Plus not a bad idea to have the current battery load tested also.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse Huge ATV Recall by Polaris - Sportsman and Scrambler

 

Thanks for the quick reply. I hadn't even considering using the pull starter so I have been jumping it with my other ATV or leaving sit on the tender for a few hours! The pull starter works just fine.

The battery has 14.4v when running. I let it run for a few minutes and then shut it off. The battery had 12.5v (it had not been on the tender for about a week). I tried to start it with the key and it wouldn't work. The solenoid makes a rapid clicking sound but does not send power to the starter.

I talked to my brother and he said the battery is about 1 year old and the starter solenoid is 6 months old. He replaced both trying to troubleshoot the problem. His theory is that the battery doesn't charge unless engine is running at high RPM's and that winch use really drains the battery. He used the ATV for utility purposes with lots of idling and winch use.

Seems like something else is going on the me. I plan to load test the battery tomorrow.

 

Update - battery failed the load test. It only had 29 cca's at 12.58 volts.

The real question is why? Battery is fairly new and this ATV has gone through several batteries in the past few years. When my brother owned the ATV it did sit unused for long periods of time so I suppose that could be the issue.

I cleaned all the contacts on the battery, solenoid and starter. I also tried the "tap the starter with a hammer" trick and it didn't help - now I know why since the battery was only putting out 29 amps. I will get a new battery and see what happens I guess.

 

Batteries can go out at any time. Main thing on any battery is to have it on a maintainer when not in use. You can get years out of most batteries and will pay for the cost of the maintainer. Plus if you need a new starter and bendix here's a cheap place. Easier just to replace than to tear into it,clean and replace the brush kit. DB Electrical - Sportsman