The Honda 400EX battery size is YTX9-BS. When looking for a new ATV battery there’s a few types of batteries to choose from. There’s wet cell conventional batteries which are the cheapest. They need to be filled with distilled water (electrolyte) and then monitored on a regular basis to make sure the lead plates are always covered with water. Another option is AGM batteries. These types of batteries are made with a glass matting that soak up the water and keep it from dissipating. This feature keeps you from never having to check the water level for the life of the battery. AGM batteries can cost 45-50% more than conventional batteries.
To maximize the life of your Honda 400EX battery avoid cranking the motor until the battery is dead. Don’t let the battery sit for prolonged periods of time causing it to go dead. Avoid storing it in places that drop below freezing temperatures. All these circumstances can shorten the life of the battery. Batteries that go in ATV’s are classified as a “starting battery” and these types of batteries are not made to be drained down and recharged and drain continuously. It’s a good habit to keep your battery on a trickle charger or battery tender when the ATV is not being ridden on a regular basis.
ATV Battery Tender
ATV Battery Terminal Protector Spray