Most electric-start portable generators use a 12‑volt, sealed lead‑acid starting battery. Common formats include AGM (Absorbent Glass Mat) and GEL, both maintenance‑free and spill‑resistant. Capacity and size vary by model, often ranging from about 7Ah to 22Ah in compact powersport-style cases (you’ll see codes like YTX5L‑BS, YTX9‑BS, YTZ14S).

• Voltage: Typically 12V.
• Chemistry: AGM or GEL are common; lithium options exist on some units.
• Fitment: Match case dimensions, terminal type, and polarity.
• Starting power: Check the cold cranking amps (CCA) your unit calls for.

Always confirm your generator’s specifications before ordering, as sizing and terminals can differ by model and year.

A quick way is to match what your generator already uses, then confirm details on the product page.

1. Read the manual/label: Note voltage, Ah rating, and any battery code.
2. Measure the case: Length, width, height, and terminal orientation.
3. Check terminals: Spade (F1/F2) vs. threaded posts, and polarity layout.
4. Cranking needs: Look for the CCA recommendation for reliable starts.

On this page, you can filter by voltage and capacity and review compatibility notes. If your old battery lists a code like YTX5L‑BS, YTX9‑BS, or YTZ14S, use that to narrow results. When in doubt, compare the specs and dimensions to ensure a snug, correct fit.

For dependable starts, focus on a starting battery with sufficient cold cranking amps (CCA) for your unit.

• AGM starting batteries: Often deliver strong cranking, handle vibration well, and are maintenance‑free.
• GEL batteries: Low‑maintenance and spill‑resistant; some models may offer lower peak cranking than comparable AGM.
• Lithium (LiFePO4): Very light with high output, but requires a compatible charging system and performance may vary in cold weather.

Match the battery’s CCA, size, and terminals to your generator’s requirements. Choosing a chemistry that suits your climate and usage can improve the starting experience, but results can vary based on engine condition and temperature.

Each chemistry has trade‑offs, so the “best” depends on your setup.

• AGM: Widely used in portable generators, good cranking performance, vibration resistance, and no water to top off.
• GEL: Stable and spill‑proof; can tolerate deeper discharges, though peak cranking output may be lower than AGM in the same size.
• Lithium (LiFePO4): Very light with long cycle life; needs a compatible charger/regulator and may require temperature‑aware management.

If you mainly need strong starts and simple compatibility, AGM is a practical choice. For occasional deeper discharge, GEL can be helpful. If weight savings and long service life matter, lithium can be attractive when your generator supports it.

A few simple habits can help keep a generator battery ready between uses.

• Charge fully: Top off after use; avoid storing it discharged.
• Use a maintainer: A smart 12V trickle/float charger can keep it at the right level.
• Disconnect parasitic loads: If storing the generator, disconnect the negative cable to reduce drain.
• Store properly: Keep in a cool, dry place and check terminals for tightness and corrosion.
• Exercise periodically: Briefly run the generator’s charging system as recommended by the manufacturer.

These steps can help preserve capacity, but battery age, climate, and usage patterns all play a role. If you’re unsure about charging or storage, consider consulting a qualified technician.