I'm not aware of any reputable motorcycle battery manufacturers intentionally designing their batteries to die after a specific period, such as 90 days. It would be counterproductive and detrimental to their reputation. Battery manufacturers strive to produce reliable and long-lasting products.
If a battery is left unused for an extended period, it can gradually lose its charge, especially if it's not properly maintained or if there is a parasitic drain in the electrical system.
Defective Battery: While it's uncommon, manufacturing defects can lead to premature battery failure. These defects could be related to the internal components, construction, or the quality control processes during manufacturing.
Improper Maintenance: Incorrect battery maintenance practices, such as failing to keep the battery charged, not using a battery tender during storage, or allowing the battery to overheat, can significantly shorten its lifespan.
Extreme Temperatures: Exposure to extreme temperatures, both hot and cold, can adversely affect battery performance and lifespan. High temperatures can accelerate the chemical reactions within the battery, leading to premature degradation.
Overcharging or Undercharging: Incorrect charging practices, such as overcharging or undercharging the battery, can have detrimental effects. Overcharging can cause the battery to overheat and damage the internal components, while undercharging can lead to sulfation and reduced capacity.
It's important to note that battery lifespan can vary depending on the quality of the battery, usage patterns, maintenance practices, and environmental factors. If you believe you have experienced a battery failure within an unusually short period, it's advisable to reach out to the manufacturer or the seller to inquire about any warranty coverage or possible defects in the battery.