A 2008 Toyota Sienna uses a standard 12-volt automotive battery (lead-acid) rather than a hybrid high‑voltage pack. The exact group size varies by trim and supplier, with common replacements fitting Group 24F or Group 35; check the battery label or the owner's manual for the precise specification.
Battery type and common sizes
The 2008 Sienna relies on a conventional 12‑volt automotive battery. The most common replacement sizes for this model are Group 24F and Group 35.
- Common replacement group sizes: Group 24F and Group 35 are the most frequently used for this model.
- Battery type: conventional lead-acid automotive battery, typically flooded; AGM options are sometimes available from aftermarket suppliers.
- Voltage and rating: 12-volt system; choose a battery with equal or higher CCA (cold-cranking amps) and similar or better capacity to meet climate and usage needs.
Always verify the exact group size and CCA on the existing battery or in the owner's manual to ensure proper fit and performance.
Replacing and maintaining the battery
Use these steps to replace or service the battery safely and effectively.
- Locate the battery label or the owner's manual to confirm the exact group size (e.g., 24F or 35) and CCA rating.
- Purchase a replacement that matches or exceeds the original CCA and is the correct group size; ensure it is a 12‑volt lead-acid battery.
- Safety: disconnect the negative terminal first, then the positive; remove any hold-down clamps and lift the old battery out carefully.
- Clean the tray and terminal connections; install the new battery, reconnect the positive terminal first, then the negative, and reattach the hold-down and covers.
- Start the engine and test electrical systems; have the alternator and charging system inspected if the battery performance remains weak after replacement.
Following these steps helps ensure a safe replacement and reliable starting performance for the 2008 Sienna.
Summary
The 2008 Toyota Sienna uses a conventional 12‑volt lead-acid automotive battery, not a hybrid pack. Common replacement group sizes are Group 24F or Group 35; verify the exact size and CCA on the existing battery or in the manual before purchasing a replacement.