STEPS
TOOLS
Connect the battery tender (charger) to your bike’s battery lead (hopefully preinstalled).
Plug in the charger and make sure its indicator shows it is working.
Adjust the cord to be free of obstructions. Wait for a few hours (perhaps overnight).
 1 Automatic Battery Charger

How to recharge a dead motorcycle battery

If you accidentally leave your motorcycle lights on the fix is fairly easy. All you need is a charger (basically a power inverter) and some patience.