The Honda Grom takes a standard 12-volt sealed lead-acid motorcycle battery, typically around 5 Ah (some years use about 6 Ah). This compact under-seat battery powers the starter, lights, and electronics; replacement is straightforward with any 12V SLA/AGM battery that fits the space and terminals.
Battery basics for the Grom
Most Grom models use a compact, maintenance-free 12V battery. Owners commonly choose sealed lead-acid (SLA) or AGM varieties because they resist vibration and require little maintenance. The battery sits beneath the seat, so the key constraints are overall dimensions and terminal layout, not just capacity.
OEM specs and model-year notes
Honda's official specs consistently call for a 12V battery, around 5 Ah for the Grom, with variations by year. The exact part number tends to change with model-year updates, so always verify the OEM replacement for your bike via the owner's manual or a dealership. If you're replacing pre-2017 models versus later ones, you may encounter slightly different dimensions or mounting hardware, but the electrical requirement remains 12 volts.
Common replacement options that fit the Grom's under-seat space typically fall into these categories:
- 12V sealed lead-acid (SLA) batteries in the 4–6 Ah range, commonly labeled as AGM-compatible units such as YTX7L-BS or YTZ7S-type batteries. These are widely available and offer good vibration resistance for small-displacement bikes.
- Smaller 4–5 Ah options (e.g., YTX4L-BS) for tighter under-seat spaces, though you must verify fitment and terminal orientation and that the capacity matches your riding needs.
When selecting a replacement, confirm the battery's dimensions fit under the Grom's seat and that the positive/negative terminals align with the bike's wiring harness. If there is any doubt, consult the owner's manual or an authorized Honda service center.
Installation and maintenance tips
Install the battery with the correct orientation and secure the battery box or straps to minimize movement. Use a compatible battery charger or trickle charger designed for 12V lead-acid batteries when the bike will sit unused for long periods. Periodic maintenance, such as cleaning terminals and applying dielectric grease, helps prevent corrosion and ensures reliable starting performance.
Summary
In short, a Honda Grom uses a 12V sealed lead-acid motorcycle battery, typically around 5 Ah, with several aftermarket AGM/SLA options that fit under the seat. Always verify model-year specifics and fitment before purchasing, and follow proper installation and maintenance practices to keep the bike starting reliably.