4 reasons why you shouldn’t start your motorcycle during the winter to keep your battery charged up

The longer I work in the motorcycle biz, the more I encounter myths about motorcycling that people believe without questioning. One came as a question, which was, “Should I start my motorcycle during the winter to keep the battery charged up?”

The question is based on a false assumption. People believe that because idling a car can slowly charge up the battery, that idling a motorcycle would do the same, but that’s not the case. Not only will idling a motorcycle in the winter not recharge the battery, but it could also damage your engine and other components. You should never start your motorcycle in the winter for the sole purpose of recharging your battery, and here’s why:

1) Starting your motorcycle in the winter doesn’t recharge your motorcycle battery

A motorcycle’s charging system doesn’t work like a car’s charging system. Idling a car might be enough to recharge the battery, but idling a motorcycle will not.

How can we prove this? Grab a multimeter and check the voltage of a healthy battery in a motorcycle at idle, wait few minutes and then check it again. The voltage will be the same, meaning idling the motorcycle hasn’t done anything to recharge the battery.

How do we know that motorcycles only charge at higher RPMs? With your multimeter still monitoring the voltage on your motorcycle battery, and your motor running, twist the throttle to rev up your engine. When your motorcycle engine’s RPMs go over a certain amount (which varies based on your motorcycle) the voltage on your battery will begin to increase. That’s the engine speed (or RPM) your motorcycle engine has to sustain in order to charge the battery. When you’re riding around the city it’s not a problem, but when you’re revving up your motorcycle for half an hour in front of your house, neighbors aren’t going to be impressed.

Your motorcycle idling might be a welcome sound (to you) in the winter, but leaving it idling won’t actually charge your battery like going on a ride would.

2) Starting your motorcycle in the winter is bad for the life of your engine and other components

After learning your motorcycle won’t recharge at idle, you might be thinking, “No problem, I’ll just start my motorcycle up and rev up the engine and keep it revved up. That will charge the battery up!” Uh, yes, kind of, but there’s more to it than that.

Your motorcycle engine’s lubrication system might have been designed by geniuses, but they were counting on you to be a little smart too. The engineers who developed your motorcycle weren’t designing it to be used in sub-freezing temperatures. Your engine’s lubrication system is not working fully until your motor is fully warmed up. Your engine’s lubrication system relies on building up oil pressure, which requires a warm engine. In the spring through the fall, warming up a motorcycle engine to optimal temperature doesn’t take very long at all, but in the winter, your motorcycle might need quiet some time to warm up. Unfortunately, while it’s still cold, you’re going to have a lot of moving parts keeping your motorcycle idling, without actually getting the lubrication that they need to avoid premature wear to your motor.

Last but not least, cold starts are very hard on your motorcycle. When your battery is cold, it puts out less power than when it’s warm out and your oil will be thicker and less runny, making it flow less. These combine to put more strain on your starter, and can cause it to wear out prematurely too.

3) Starting your motorcycle in the winter can create condensation, which isn’t good

Another reason not to start your motorcycle in the winter is the condensation that this can create. When you start your motorcycle, you’re setting fire in a cold metal internal combustion engine. As the engine warms up, moisture from the air that’s in your crankcase will cause condensation (water) in your engine. What happens to this water inside your metal engine is up to you:

If you turn off your motorcycle before it has reached and maintained it’s optimal temperature for a decent period of time, that water inside your engine will not evaporate. Instead, it becomes the weird white cloudiness you see in your engine oil, or sticks to your oil fill cap, or your oil dipstick, or goop in your valve cover. Overall, none of this is good for your motorcycle’s engine.

If you take your motorcycle out for a good ride of at least half an hour the condensation will evaporate. Of course, you might have to deal with salty roads and other motorcycle winter riding problems, but that’s a whole other article.

4) Starting your motorcycle in the winter is kills your battery more than it charges it

One of the hardest things for a motorcycle battery to do is to start your motorcycle. Think of your motorcycle battery as a bank account. Every time you hit the starter, you’re withdrawing power out of your account to get the motorcycle started. If your motorcycle isn’t being taken out for a ride, all you’ve done is withdraw power, without putting any power back in. You can only make so many withdrawals before your before your battery is left empty.

If your plan is to just start the motorcycle, over and over, and never actually ride the bike to put power back into your battery, you’re just going to end up depleting your motorcycle battery, not refilling it. Motorcycle batteries don’t do well with being left unfilled, it can harm their overall lifespan, so by starting your motorcycle and not recharging your battery properly, you’re actually hurting it.

If it’s too late, and you’ve already found yourself with a dead battery, here’s how to tell if a dead motorcycle battery will still work perfectly after recharging it, or if it needs to be replaced.

“But what about…”

Before you rush down to the comments section, yes, you’re right, there are some great reasons to start your motorcycle in the winter:

A motorcycle is full of moving parts and those parts should be moved periodically. Tires rolling forward and back are less likely to get flat spots. Fuel flowing through fuel lines and injectors or carburetor jets are less likely to gunk up. Neglect is one of the biggest causes of a motorcycle not starting, so you should try to avoid it. The more love you can give your motorcycle, the better. No argument there. But what I’m saying, is that versus starting your motorcycle as a strategy for maintaining your battery. It’s just a bad idea.

So what should you do?

You should take proper care of your motorcycle, and that means, learning about how to winterize a motorcycle properly. Check out the link to the article I wrote, it only takes half an hour, a $3 bottle of fuel stabilizer, and $25 for a Battery Tender Jr. battery charger.

Follow the steps in my article above, treat your fuel, hook up your battery to a Battery Tender Jr. trickle charger, and then roll your bike forward or backward a couple inches every month. If you want to start your motorcycle, that’s fine, but make sure you take it for a good ride if you do.

Conclusion

Starting your motorcycle during the winter is fine once or twice to keep your fluids flowing, but you shouldn’t do it as a means of keeping your motorcycle battery charged up.

Starting your motorcycle during the winter won’t charge your motorcycle battery, in fact, it will just draw from your battery’s power without recharging it. Your motorcycle isn’t meant to be run for short periods in cold conditions, and you can damage your starter or even cause condensation to form inside of your motor which could cause premature wear.

Ultimately, the best thing to do is winterize your motorcycle properly. Check out this article I wrote on how to winterize your motorcycle, it’s the best thing you can do for your motorcycle before putting it away, and if you follow my instructions it will only take half an hour.