Mighty Max Battery 12V 35AH U1 Lithium Replacement Battery for John Deere Lawn Tractor-Riding Mower 108

What It Is

The Mighty Max Battery 12V 35AH U1 Lithium is a direct drop-in replacement for the lead-acid battery in John Deere lawn tractors (e.g., 108, D100 series) and other riding mowers requiring a U1 group size. It delivers 35 amp-hours of capacity for reliable starting and accessory power, with the weight and maintenance benefits of lithium chemistry.

Fitment & Compatibility

• Check your mower’s battery group: This is a U1 (UB1) size battery—measure your current battery’s dimensions (approx. 7.75"L x 5.25"W x 6.25"H) and terminal location (top posts, positive left). If your mower uses a different group (e.g., U1R or U2), it won’t fit.
• Confirm voltage: Must be 12V (most riding mowers are). This is not for 6V systems.
• OEM vs. aftermarket: Replaces John Deere OEM part numbers like AM100603, AM101334, or AM101335, but also works with many other brands (Cub Cadet, Husqvarna, Craftsman) using U1 batteries. Verify your mower model’s battery spec in the manual.
• Deck size irrelevant: Battery fitment is independent of deck width—only the battery tray dimensions and terminal orientation matter.
• Cranking amps vs. CCA: This battery has 350 cold cranking amps (CCA). Compare to your original battery’s CCA rating; if your mower has a larger engine (over 20 HP) or extreme cold starts, ensure 350 CCA is sufficient.

Key Things to Know

• Weight savings: ~4 lbs vs. 15-20 lbs for lead-acid—easier to handle and reduces mower weight slightly.
• Charging system compatibility: Lithium batteries require a specific charging profile (13.8-14.6V). John Deere’s stock charging system (typically 13.5-14.5V) usually works, but if your mower has an older or unregulated charger, you may need a lithium-compatible charger.
• Installation: Direct swap—remove old battery, clean terminals, connect (red to positive, black to negative). No modifications needed if terminal orientation matches.
• Cold weather performance: Lithium batteries lose some capacity below freezing but still start better than lead-acid in moderate cold. Avoid charging below 32°F.

Should You Buy It

Buy this if you want a lighter, longer-lasting battery for your John Deere or other U1-compatible riding mower, and you’re comfortable with lithium’s charging requirements. It’s a solid upgrade for frequent users who want to avoid lead-acid maintenance and weight. Skip it if your mower has a non-standard battery tray, requires high CCA (over 400), or if you’re on a tight budget—lead-acid U1 batteries cost half as much.