Honda Trx 400EX Battery
1999–2008. The OEM battery case the Trx 400EX takes, the lithium that drops into it, and every model year we have on file. One case across the whole run.
2008 Honda Trx 400EX
- OEM battery
- YTX9-BSYuasa 2026 OEM guide
- Case family
- YTZ1012V starter case
- Fits all years
- 1999–2008same case every year on file
The Honda Trx 400EX takes the YTX9-BS case. The Antigravity ATZ-10 RE-START is a drop-in for that case: 360 cranking amps, 2.6 lb, a built-in jump start that saves enough charge to get you home.
See the Antigravity ATZ-10
Trx 400EX battery by model year
| Model years | OEM battery | Where it comes from | Lithium that fits |
|---|---|---|---|
| 1999–2008Your year · 2008 | OEM batteryYTX9-BS12V starter case | Where it comes fromYuasa 2026 OEM guideAntigravity fitment list agrees | Lithium that fitsAntigravity ATZ-10 RE-START →Antigravity ATZ-10-HD RE-START →Ionic S4 → |
Trim covered: Trx 400EX.
Shop all Honda ATV batteriesWhat the Trx 400EX needs, in plain English
Every Trx 400EX from the first 1999 model through 2008 starts on the YTX9-BS case, a 12-volt starter battery. Honda ships it with a lead-acid battery that starts to fade after two or three seasons of short rides and off-season storage, and that is usually the day a rider goes looking for something better.
The lithium drop-in is the Antigravity ATZ-10 RE-START: 360 cranking amps, 2.6 pounds, the same case in lithium. Its RE-START function puts the battery to sleep before a parasitic draw can drain it, then wakes it with one press for a jump start. Charge it with a lithium-compatible charger or maintainer for the off-season and it outlasts the lead-acid battery it replaces by years.