Owners of motorcycle or ATV always complain about their batteries. If you dont have a motorcycle battery charger or a battery trickle charger, you will definitely have problems. A battery will self-discharge at the rate of 5% per month just sitting around. It would seem logical to assume that a low battery can be charged simply by riding your bike or atv. A low battery cannot be fully charged by riding the bike, no matter how far you go.
Lets start with the battery. If the bike is not in use for 30 days, the battery should be placed on charge with a 2 amp or smaller battery trickle charger for 24-48 hours every 30 days with no usage. This would be a very good idea on bikes that are ridden only once or twice a month as well. Most automotive battery chargers charge at 6, 10, or greater amperage. Using a motorcycle battery charger like that will overheat the battery, warping the plates inside until they ground out against each other, shortening battery life. A battery should never be charged at more than 10% of its rated capacity. The largest battery in our industry is 20 amps, so 2 amps is the maximum charge rate for that battery. Anything more will damage it.
Besides damaging the battery when charging at excessive amperage, the battery remains low on charge after the quick charge, and the same damage will occur, even if you are successful in getting the bike to start. Then the charging system will be strained running the bike with the low battery, possibly causing damage to the alternator components.
When a battery is in a low state of charge (for a period of time), the acid in it separates (as mentioned in last paragraph). This causes a condition known as sulfation. Sulfation causes deterioration of the lead plates inside the battery, leading to an early failure. The lower that the batteries state of charge becomes, the faster sulfations effects take over, weakening the battery quicker.
Once a battery has been left completely dead, they will almost always not come back from that totally dead condition. The handful that will, are almost never very reliable or very strong again.
The bottom line to this battery deal is to work to never let the battery go dead or stored in a low state of charge.
It is best to think of motorcycle battery chargers or battery trickle chargers as a maintenance system. A motorcycle battery chargers or battery trickle chargers are basically designed to replace the energy required to start the motorcycle. In effect, a battery that started the bike at 80% charge, will likely only get to 80-85% after running. Not only will riding the bike with a low battery not fully charge the battery, this causes the battery charger to charge as hard as it can while trying to charge the low battery. A motorcycle battery charger or battery trickle charger are not designed to stay at full charge level for extended periods. When required to do so, this over heats rectifiers, stator windings, and regulator components causing them to fail. This only adds to the cost of replacing the battery that was failing anyway.
A motorcycle battery charger or battery trickle charger can be purchased for below $40. If you prefer not to have to remember to plug/unplug the charger during storage, a battery trickle charger is a great solution as they can be left plugged in.