# Varta A7 vs A6: the differences and which to choose

> Varta A7 (70 Ah, 760 A, L3 case) vs A6 (80 Ah, 800 A, L4 case): two Start-Stop AGM batteries. What differs and which fits your car.

- **Canonical URL**: https://bateriasonline.es/en/varta-a7-vs-a6-agm-battery
- **Language**: en
- **Last update**: 2026-11-11

Updated: 6 November 2026 · Technical data from the manufacturers' datasheets ([how we write our datasheets](https://bateriasonline.es/en/how-we-write-our-battery-datasheets))
The Varta A7 and A6 are the same Start-Stop AGM design in two sizes. The A6 has 10 Ah more capacity and 40 A of extra cold cranking compared with the A7, but it is also 37 mm longer: the A7 comes in an L3 case (278 × 175 × 190 mm), the A6 in an L4 (315 × 175 × 190 mm). So this is less a question of picking the stronger one and more about recognising which one your car was built around, because the battery tray settles it for you.
If the old battery in your car says E39 or F21, you are in the right place too: those are the previous names of the A7 and the A6.

## Both AGM batteries, spec by spec

| Spec | Varta A7 | Varta A6 |
|---|---|---|
| Range | VARTA Dynamic AGM | VARTA Dynamic AGM |
| Technology | AGM | AGM |
| Voltage | 12 V | 12 V |
| Capacity | 70 Ah | 80 Ah |
| Cold cranking (EN) | 760 A | 800 A |
| Dimensions (L × W × H) | 278 × 175 × 190 mm | 315 × 175 × 190 mm |
| Case | L3 | L4 |
| Weight | 20.3 kg | 22.56 kg |
| Polarity | Positive terminal on the right | Positive terminal on the right |
| ETN code | 570 901 076 | 580 901 080 |

## What really sets them apart

- **Case length.** Width (175 mm) and height (190 mm) are shared; the A7 is 278 mm long and the A6 315 mm. That alone means an A6 will not go where an L3 belongs.
- **Stored energy.** 80 Ah versus 70 Ah: the A6 holds 14 % more to keep the electronics alive while the engine is off at the lights.
- **Starting current.** 800 A on the A6, 760 A on the A7.
- **Weight.** The A6 weighs 22.56 kg; the A7, 20.3 kg.
- **What they have in common:** AGM technology, the VARTA Dynamic AGM range, 12 V and the positive post on the right.

## Getting the right one

- **The [Varta A7](https://bateriasonline.es/en/varta-a7)** suits cars running an A7, an E39 or any other 70 Ah AGM in L3 format.
- **The [Varta A6](https://bateriasonline.es/en/varta-a6)** suits cars running an A6, an F21 or any other 80 Ah AGM in L4 format.
- **Keep the original size.** Dropping an A7 into an A6 tray leaves it loose on the base and below the capacity the car maker specified; the other way round, the A6 simply will not fit.
- **AGM in, AGM out.** A car that left the factory with AGM cannot take an EFB such as the [Varta N70](https://bateriasonline.es/en/varta-n70) or the [Varta N80](https://bateriasonline.es/en/varta-n80), let alone a conventional battery. Going upwards is fine: an A7 is an upgrade over an N70, and an A6 over an N80, with identical dimensions.

## E39 became A7, F21 became A6

When Varta refreshed its AGM line-up, these two batteries were renamed without any change in performance: the old Varta E39 is now the A7 and the old Varta F21 is the A6, with matching capacity, cranking, case and polarity. The F21 and A6 even share the ETN 580 901 080, the 9-digit number that pins down the specification. The full story behind the E39 change is told in [Varta A7 (formerly E39): what changed and equivalents](https://bateriasonline.es/en/varta-a7-e39-agm-battery-equivalents).

## Other brands that match the A6

Exide, Tudor, Fulmen and Deta flag their AGM batteries with a K in the code. These are the ones in our range that pass our equivalence rules as a replacement for an A6:

| Battery | Brand | Technology | Capacity | Cold cranking (EN) | Dimensions (L × W × H) | Polarity |
|---|---|---|---|---|---|---|
| Exide EK820 | Exide | AGM | 82 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |
| Tudor TK820 | Tudor | AGM | 82 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |
| Fulmen FK800 | Fulmen | AGM | 80 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |
| Fulmen FK820 | Fulmen | AGM | 82 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |
| Deta DK800 | Deta | AGM | 80 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |
| Deta DK820 | Deta | AGM | 82 Ah | 800 A | 315 × 175 × 190 mm | Positive terminal on the right |

For the A7, see the A7 guide linked above or the complete table in [Varta, Bosch, Exide and Tudor car battery equivalents table](https://bateriasonline.es/en/varta-bosch-exide-tudor-car-battery-equivalents). If you are coming from Bosch, the one with the same ETN is the S5 A08 for the A7 and the S5 A11 for the A6; we mention it purely as a pointer, since we do not sell that brand.

## When the car does not use AGM

For a Start-Stop car that came with EFB, the comparison you want is [Varta N60 vs N70: how the two EFB batteries differ](https://bateriasonline.es/en/varta-n60-vs-n70-efb-battery), which also shows when moving up to AGM is worthwhile. And if your car has no Start-Stop and runs a conventional L3 battery, an AGM is not required; in that case weigh up the [Varta E11](https://bateriasonline.es/en/varta-e11) against the [Varta E44](https://bateriasonline.es/en/varta-e44) in [Varta E11 vs E44: the differences and which to choose](https://bateriasonline.es/en/varta-e11-vs-e44-car-battery).
All our other Start-Stop AGM batteries are in [AGM Start-Stop batteries](https://bateriasonline.es/en/agm-start-stop-batteries).

## Frequently asked questions

### Will a Varta A6 fit where an A7 goes?

In most cars, no, because the A6 is 37 mm longer than an L3. It only fits if the tray was designed for an L4 case.

### Can I use an A7 if my car has an A6?

We advise against it: it would sit loose in the clamp and offer 10 Ah less than the car expects for its Start-Stop.

### Are the F21 and the A6 the same battery?

Yes. The A6 succeeds the F21: the same 80 Ah and 800 A, L4 case, positive on the right and the same ETN, 580 901 080.

### Why won't an EFB do in a car with factory AGM?

Because it copes less well with deep discharge cycles, and the Start-Stop system was set up at the factory around an AGM. An AGM, on the other hand, can take the place of an EFB of the same format.

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*bateriasonline.es — Batteries and accessories · 2026-11-11*