The Ford Focus ST uses a 12-volt battery.
In practice, the exact battery size and type can vary by model year and market. Most Focus STs rely on a 12V lead-acid battery located in the engine bay. If your car is equipped with a Start-Stop system, Ford often specifies an AGM (absorbed glass mat) battery to endure frequent cycling. Always verify the correct group size (battery fitment), cold-cranking amps (CCA), and capacity (Ah) from your owner's manual or the battery label before purchasing a replacement.
Battery types and compatibility
There are two main 12-volt battery options for Ford Focus STs depending on the electrical load and market: standard flooded lead-acid (maintenance-free) and AGM (for Start-Stop). AGM can better handle frequent starts and deeper discharge, which some models require if they have an energy-recovery or Start-Stop system. The exact group size and capacity vary; common Ford-fitment in North America is Group 96R for many models, but the correct specification can differ by year and market. Always confirm with the owner's manual or Ford's official parts catalog for your VIN.
Start-Stop and electrical load
If your Focus ST is equipped with a Start-Stop feature, the manufacturer typically recommends an AGM battery with higher CCA and capacity. Non-Start-Stop variants often use conventional sealed lead-acid batteries. Always confirm via the owner's manual or Ford's official parts catalog for your VIN.
How to identify the correct battery for your Focus ST
To ensure you install the correct battery, follow these verification steps:
- Check the owner’s manual or the battery label for the recommended battery group size (for example, Group 96R) and the required CCA and Ah ratings.
- Inspect the current battery in the engine bay: note the group size printed on the label and the terminal configuration.
- Verify that the replacement matches the exact fit in the battery tray, clamps, and cable routing.
- Confirm whether your model has Start-Stop; if so, choose an AGM battery with sufficient CCA and capacity.
- Consider climate and typical use (short trips, heavy electronics) when selecting a battery with higher capacity.
Following these steps helps ensure reliable starting performance and compatibility with your car’s electrical system.
Replacement options and maintenance
When replacing, you have several options, including OEM Ford batteries and reputable aftermarket brands that meet the same specifications. Here are common choices:
- OEM Ford battery designed for your exact model and year (highest compatibility and warranty).
- Aftermarket maintenance-free 12V batteries that match the required group size and CCA, such as Bosch, VARTA, Exide, or other reputable brands—confirm whether AGM is required vs. flooded lead-acid.
- AGM replacement if your Focus ST has Start-Stop; ensure the replacement is rated for Start-Stop and has sufficient CCA and Ah.
- In colder climates, select a battery with higher CCA to improve engine starting in winter.
Always ensure the battery’s physical dimensions, terminal layout, and hold-down fitment align with your vehicle's factory mounting hardware.
Summary
In brief, the Ford Focus ST uses a 12-volt battery. The exact group size and type depend on year and market, with AGM variants commonly required where Start-Stop is present. Check your owner’s manual or the battery label to buy the correct size, rating, and fit. If unsure, consult Ford’s parts catalog or a qualified technician for the correct specification.