What is the difference between H6, H7 and H8 batteries?

Physical size and output. H6 (L3) is ~278mm long and ~70 Ah; H7 (L4) is ~315mm and ~80 Ah; H8 (L5) is ~352mm and ~90–95 Ah. Each step up fits a larger, higher-demand vehicle, but the tray must accept the bigger case.

Can I replace an H7 with an H8?

Only if the tray, hold-down and cables accept the longer H8 case. The H8 is ~37mm longer than the H7, so it will not fit an H7 tray. Confirm the physical dimensions before upgrading.

Lead-Acid Knowledge · Battery Groups · Last reviewed 2026-09-14

H6 vs H7 vs H8 Battery: Size, Capacity, CCA and Which Car Each Fits

H6, H7 and H8 are the three most common European passenger-car groups, and they differ mainly in length and output. The choice is usually settled by the tray — if the bigger case does not fit, the comparison ends there.

Direct answer: H6 (L3) is ~278mm and ~70 Ah, H7 (L4) ~315mm and ~80 Ah, H8 (L5) ~352mm and ~90–95 Ah — each step up is a longer case with more capacity and CCA for a larger vehicle. The tray decides: you can only upgrade to a bigger group if the case physically fits, because the three are not interchangeable in length.

The three groups side by side

	H6 (L3)	H7 (L4)	H8 (L5)
Length × width × height	~278 × 175 × 190 mm	~315 × 175 × 190 mm	~352 × 175 × 190 mm
Typical capacity	~70 Ah	~80 Ah	~90–95 Ah
Typical CCA (EN)	~640–700 A	~760 A	~850–900 A
Typical vehicle	Midsize car / start-stop	Large car / SUV	Large SUV / light truck

Dimensions are typical; height varies slightly with terminal type. Always confirm against the original battery before ordering.

Why the difference is mostly length

All three groups share the same width (~175mm) and height (~190mm); what grows is the length. A longer case holds more plate surface area, which raises both capacity and CCA. The trade-off is physical: a car's tray is sized for a specific group, and a longer battery simply will not drop in or clamp down.

Which one do you need?

H6 (L3) — the modern start-stop default for midsize petrol and diesel cars; balanced size and output.
H7 (L4) — large cars and SUVs with higher electrical load (heated seats, telematics, start-stop).
H8 (L5) — large SUVs and light trucks with the highest accessory and cranking demand.

The rule is match the group to the tray first, then confirm the CCA meets the engine and climate — see battery group sizes and what is CCA.

Common misconceptions

"A bigger group is always a better battery." It is more output, but it must fit the tray — an H8 in an H6 tray is a non-starter.
"H6, H7 and H8 are interchangeable." No — they differ in length, so they are not physically interchangeable.
"Higher CCA means I should upsize." Only if the tray allows it; otherwise buy the correct group with the CCA the engine needs.

Key takeaways

H6 → H7 → H8 is a length and output ladder (~278 → ~315 → ~352 mm).
Bigger group = more capacity and CCA, but only if the tray accepts it.
Match the group to the tray, then the CCA to the engine and climate.
H6 is the start-stop default; H7/H8 are for larger, higher-load vehicles.

The Author's Take

Position: The H6/H7/H8 question almost always answers itself the moment you measure the tray — the group is a physical constraint first and a performance choice second.

Reasoning: People compare CCA across the three groups when the deciding variable is 37 millimetres of case length. Upsizing to an H8 for "more power" fails the moment the battery will not fit. The correct sequence — measure the tray, read the current group, then confirm CCA — removes the entire dilemma.

This is the author's editorial view, not a purchasing guarantee.

Sources

Dimensions and CCA ranges cross-verified from manufacturer datasheets (Varta, Bosch, Exide, Yuasa) and the BCI group-size reference. Values are typical ranges, not a substitute for a specific battery's datasheet.

Battery Council International (BCI) — group-size and dimension definitions.
EN 50342 — European starter-battery standard (CCA basis).
Manufacturer fitment guides — H6/H7/H8 dimensions and CCA.

Last reviewed: 2026-09-14