Monster Marine Lithium’s “MML” warranty consists of three Tiers as described below.

Monster Marine Lithium offers an industry best 15 Year Warranty.
MML 15 Year Warranty consists of Tier 1, Tier 2, & Tier 3 benefits. Prohibited Actions and
exclusions (described below) apply.

Free lifetime technical support & free battery analysis. Batteries and chargers must be registered within 60 days of purchase date. If the battery or charger is not registered within 60 days of purchase warranty will be based on the manufacturer date of the battery.

Tier 1 Term Limit: Years 0 to 5
Tier 2 Term Limit: Years 5 to 10
Tier 3 Term Limit: Years 10 to 15

Tier 1: Years 0-5. Manufactured Defective Battery is replaced at no cost to owner throughout Tier 1 term limit (no charge cycle limitation). MML is responsible for returning shipping labels to MML’s address and will supply return shipping labels via email to battery owner. Battery owner is responsible for return shipping cost from MML’s address to battery owner’s address.

Tier 2: Years 5-10. Manufactured Defective Battery is repaired at no cost to owner throughout Tier 2 term limit, while there will be a 2000 charge cycle limitation throughout Tier 2. This clause means between 2000 & 2500 charge cycles the battery is deemed to be in Tier 3 and falls under Tier 3 warranty provisions. Throughout Tier 2 battery owner is responsible for all shipping costs. If battery can not be repaired a 50% pro rate will be offered to original purchaser of battery.

Tier 3: Years 10-15. Manufactured Defective Battery is repaired (please allow 2 weeks minimum for repairs), battery owner is responsible for repair parts cost, if not repaired, battery can be replaced at 30% from current MSRP. Battery owner throughout Tier 3 term limit is responsible for all costs to replace the battery minus the estimated 30%. In addition, there will be a 2500 charge cycle limitation throughout Tier 3. This clause means after 2500 charge cycles the battery is deemed to be at the end of normal life and has no replacement value.

Chargers, accessories, and any other MML products have a one-year factory defect non-transferable warranty. The Dynamic Charger has a 3 year full replacement warranty.

Clothing attire, caps, etc. have no warranty.

Realize MML has a goal to supply quality products while being honest and transparent to their customers. MML expects the same type of courtesy and partnership from their customers. If products have been tampered with or altered, such actions will subject the product to a possible voided warranty. Some examples are, serial number tampering, label altering, unapproved modifications, or removal of codes and numbers.

MML has spent extra time and effort designing chargers that charge, maintain, and bring lithium batteries out of protective modes. Unfortunately, the vast number of chargers on the market today do not have all these features and can result in a damaged battery. The most frequent neglect noticed is when lithium batteries go uncharged for long periods of time due to not having maintenance charging while the battery is in storage. Regularly MML has noticed that a small parasitic negative amperage draw is taking place when the battery is stored. This often is from items attached to the battery that requires power even when stored. Without the charger maintenance feature this can result in a damaged battery. If it is deemed that battery damage is a result of improper charging, battery warranty will be voided. MML is willing to repair the battery (if repairable) although the battery owner will be responsible for repair cost. Our advice is to make sure the battery is charged upon putting in storage and disconnect everything from the battery. Please charge the battery every 30-60 days to avoid potential warranty being voided.

Although MML prides itself on developing a robust and durable marine battery, we do not recommend submerging the battery under water, which can result in battery damage. If the battery is deemed to be defected due to water damage, warranty will be voided. MML is willing to repair the battery (if repairable) although the battery owner will be responsible for repair cost.

All Monster Marine Lithium Warranties are only available to the
United States lower 48 states. If outside the lower 48 states, contact MML to discuss warranty options.

Returns will have a 15% restocking fee plus shipping charges to and from MML applied to unopened, unused items unless approved otherwise through the warranty department.

Returns of opened/used batteries, chargers, accessories will incur a 20% restocking fee plus all shipping cost to and from Monster Marine Lithium Batteries. MML will not accept returns after 30 days. Cost of shipping items back to MML is the responsibility of the purchaser.

Eligible returns must be sent back within 30 days of purchase date (proof required)

All product contents including paperwork must be returned with original box or packaging when returning MML products.

Warranty only applies to the original purchaser and will not follow the battery when changing ownerships.

Monster Marine Lithium Batteries Inc. reserves the right to deny any warranty claim for any reason.

For customers who have bought batteries prior to the 15 year warranty change and have the 5 year warranty do not worry warranty will transfer over. Please register your current batteries and chargers using the registration link by May 2024 to be eligible. If your battery or charger does not have a serial number please use the model number (MML-etc).