Battery maintenance is often overlooked but almost just as important as an oil change, especially if you have a fuel injected dirt bike. I am not just referring to charging the battery but also checking the battery.
Constant contact between the cables and battery is absolutely necessary. Keep in mind, anything that can be tightened can also come loose. Be sure to check the battery terminals where the cables connect to ensure they are tight. If not, the bike will not receive full charge.
If it is a lead acid, sometimes it can leak. It will be white stuff around the battery terminals. Do not touch or sniff it. Put on gloves and remove the cables. Use baking soda while scrubbing with a wire brush to get rid of it. If left alone, the terminals can corrode.
Ensure the battery is secure in the bike. If the battery moves around, it can be ruined or temporarily not work.
Keep up on charging. If the bike is going to sit awhile, hooking up a battery tender is not a bad idea. If the battery charge gets low it could ruin the battery. Fuel injected four strokes are voltage sensitive and it is hard on the bike to let the battery go low. IMPORTANT - If you use a lithium battery make sure the battery charger used is for lithium batteries!
I recommend a good quality battery. It can make or break you! I have had excellent luck with WPS house brand, Fire Power featherlight lithium batteries! I have one in both of my bikes and one of them is almost 4 years old with no issues! Lead battery wise, I recommend Yuasa. I know light batteries are the thing now but some manufactures, such as Beta, recommend a lead acid battery in their four strokes.