The Bosch S4 battery series is a well-known range of maintenance-free lead-acid batteries designed to deliver reliable performance for a wide variety of conventional vehicles. Positioned above the entry-level S3 series, S4 batteries offer increased starting power, longer service life, and better cold-cranking capabilities, making them a solid upgrade for everyday drivers. These batteries are built using Bosch’s proven calcium-silver alloy technology, which improves resistance to corrosion and enhances electrical flow. The S4 line is ideal for vehicles without start-stop systems but with a moderate demand for electrical support, including electric windows, audio systems, and other in-car electronics.
The Bosch S40 25 is a compact but powerful model within the S4 lineup, offering 60 Ah of capacity and 540 A of cold cranking current. It’s well-suited for small to mid-sized petrol or diesel vehicles, especially those that operate in a range of climates and require dependable cold starts. One of the distinctive features of this model is its reverse terminal layout (1)—meaning the positive terminal is located on the left side when viewed from the front. This is less common in European vehicles, where terminal layout 0 (positive on the right) is the norm, so care must be taken to ensure compatibility with the vehicle’s cable routing.
In terms of dimensions, the S40 25 measures 232 mm in length, 173 mm in width, and 225 mm in height, placing it close to the D23 size standard—a format often used in vehicles from Japanese and Korean manufacturers. This size, combined with the battery’s B0 mounting type (no bottom ledges for hold-down clamps), clearly indicates that the S40 25 is intended for specific vehicle models that require a smooth-base design. The absence of side or bottom flanges (as found in B1 or B13 configurations) means it must be installed in vehicles with trays that secure the battery from the sides or top.
With its terminal type 1 (standard European posts), the S40 25 can be installed in most vehicles that accept this post type. However, the installer should always verify the terminal position and the battery tray design before selecting this model. It’s especially important when replacing batteries in vehicles with limited cable length or where terminal polarity must match the original battery layout exactly.
When compared to similar batteries like the Varta Blue Dynamic D48 or Lucas Premium LP014, the Bosch S40 25 holds its own. All three offer 60 Ah of capacity and 540 A of starting power, but Bosch benefits from a reputation for high manufacturing standards and long-term performance. While Varta’s D48 is practically identical in terms of size and specification, Bosch may appeal more to drivers looking for premium brand recognition and trusted reliability. Lucas’s LP014 is also a strong alternative, especially for vehicles originally fitted with Korean-style batteries.
In conclusion, the Bosch S40 25 is a dependable and high-performing battery for vehicles requiring a reverse-polarity, compact-format battery with a smooth B0 base. Its 60 Ah capacity and 540 A starting current provide ample power for most standard vehicles, while its design makes it ideal for Asian models or specific European cars with tight engine bays and non-standard mounting trays. As part of the trusted S4 series, it delivers Bosch quality, consistent starts, and peace of mind over the long term.