The Honda FourTrax 300 typically uses a 12-volt lead-acid motorcycle-style battery around 8–9Ah. A common replacement is the YTX9-BS or an equivalent 12V battery. Always verify by checking the existing battery label or your owner's manual.
Battery size can vary by model year and regional market. Some TRX300s use maintenance-free sealed AGM batteries, while older versions may have flooded lead-acid units. Fitment also depends on the battery tray dimensions and terminal layout, so double-check measurements and polarity before buying a new battery.
Common battery options and fit considerations
Below is a concise guide to typical replacement options and what to check to ensure a proper fit for your FourTrax 300.
- YTX9-BS: 12V, approximately 8–9Ah, maintenance-free AGM type; widely used on Honda ATVs and a common choice for the TRX300 when the tray size allows.
- YTX12-BS or equivalent: 12V, approximately 12Ah; offers more reserve power but requires a larger tray area and securement space.
- Other OE-equivalent 12V batteries: look for the same voltage, a similar or compatible capacity (Ah), and the same positive/negative terminal arrangement to match wiring harnesses.
Note: Battery dimensions and terminal layouts vary by brand and model. Always verify fit by measuring the battery tray and comparing with the replacement’s specifications, including terminal positions and hold-down compatibility.
Installation notes and maintenance tips
During replacement, disconnect the negative terminal first, then the positive, and ensure the terminals are clean and tight. Use a proper hold-down to secure the battery against vibration. If upgrading to an AGM battery, you may enjoy easier maintenance and better cold-weather starting, but ensure the new battery fits physically and electrically with the bike’s charging system.
How to confirm the right size for your specific TRX300
To be certain you buy the correct battery, check your model year, regional variant, and the OEM battery label. Compare voltage (12V), capacity (Ah), and terminal layout with the replacement you’re considering, and verify that the battery tray and hold-down will accommodate any size increase if you plan to go higher than the stock capacity.
Summary: For most Honda FourTrax 300 ATVs, you’ll use a 12V battery around 8–9Ah, with the YTX9-BS being a common replacement. If you need more reserve power and your tray allows, a higher-capacity option like a YTX12-BS can work. Always confirm with the manual and verify physical fit and terminal orientation before purchasing.