Keeping a Vintage Motorcycle Charged and Ready to Ride

Which battery charging system is the best for a vintage Kawasaki H1?

Using a 10-amp battery charger to maintain your vintage motorcycle's battery.
Using a 10-amp battery charger to maintain your vintage motorcycle's battery.©Brian Maclean

Question I have a restored vintage bike, a Kawasaki H1 triple, that I ride infrequently but want to keep ready to go at a moment's notice. My mechanic recommended filling the tank with ethanol-free gas with a stabilizer mixed in to keep the carbs happy, and he also suggested keeping the bike plugged into a trickle charger. I have an old 10-amp charger, but it doesn't have a "maintainer" function. Would plugging the battery in for a few hours every month serve the same purpose, or should I get a proper trickle charger? The bike has a modern AGM battery.
Tom Gustovson / Via Email

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Answer We're skeptical about the charging routine you propose, especially if the idea is to have the bike ready to ride "at a moment's notice." If that moment comes almost a month since the last time you charged the battery, it might not start the bike. And if you forget to disconnect the charger, it can fry your battery pretty fast. That 10-amp charger you have is likely an automotive charger designed for large-capacity car batteries, and unless it has a switch that allows you to lower the amperage (to say 1 or 2 amps), you should avoid using it on your H1's battery. Your mechanic has the right idea. The "trickle" charger he's talking about is more commonly known as a float charger. It charges the battery to a specified level then switches itself off until the battery's natural discharge drops the voltage below a certain point then switches back on and brings the voltage back up. Additionally, most modern chargers use some pretty advanced charging sequences to help keep your battery in peak health. The beauty of a float charger is that you can leave it connected to the battery all the time so the bike will be ready to go when you are.