Varta N105 Dynamic EFB · Start-Stop battery 105Ah 950A

Yes, it is EFB: a flooded lead-acid battery whose plates carry reinforcing additives (what is an EFB). It withstands more cycles than a conventional battery but fewer than an AGM, and it is fitted to cars with basic Start-Stop, without regenerative braking. It is more affordable than an equivalent AGM.

Yes, the EFB technology of the N105 is built for Start-Stop. EFB batteries cover basic Start-Stop (no regenerative braking). If the car recovers energy when braking, AGM is recommended for its higher cycle count; for basic Start-Stop, EFB. The manufacturer's specification comes first. Once fitted it is ready to go; registering it via OBD, advisable on most modern models, lets the alternator charge with the optimum profile.

With a 10 mm spanner, swapping in the Varta N105 takes 15 to 30 minutes on most cars; if the battery sits in the boot or under a seat, allow up to twice as long. With the engine stopped and the key removed, always start with the negative (−) terminal, then the positive (+). Free the clamp, swap the battery without turning it round (this one has positive on the right) so the polarity stays the same, and reconnect in reverse: positive (+) first, negative (−) last. On cars with Start-Stop or BMS, registering the battery via OBD makes the alternator charge with the correct profile. Mind the IBS sensor on the negative terminal too: loosen the cable nut, not the sensor. And the replacement must be the same technology (AGM or EFB) or higher: a conventional battery fails within months. If the car manufacturer lists any extra step in the handbook, follow it. More detail in how to replace the car battery.

There is no exact figure: for a battery such as the Varta N105 (EFB), a reasonable guide is 4 to 6 years in basic Start-Stop car use. Actual lifespan varies with climate (cold starts, heat evaporating the electrolyte), with usage and short journeys, with the condition of the alternator and charging system, with power draw while parked and with maintenance; the type of car and Start-Stop also count.

It measures 394×175×190 mm in length × width × height, with the terminals included in the height; that is the European L6 case size. Measure the battery tray before ordering: a one-millimetre difference is enough for the hold-down clamp not to close.

It has the positive on the right (polarity). Put it in front of you, terminals towards you: the post with the red ring and the + sign is the positive. A change of polarity from the original means longer cables or a reconfigured system and can cause a short circuit: check it before ordering.

The quickest way is to enter your number plate in the finder: DGT/DVLA/KBA detect model and engine. You can also look at the "Compatible vehicles" tab, verified by our technical team, or send us make, model, engine and year on WhatsApp; we answer during business hours (Mon–Fri 10:00–13:30 and 16:30–18:00 (Spanish time, CET)). Our database holds 12 verified vehicle versions for the Varta N105. In every case, the car manufacturer's specifications (owner's handbook) take precedence.

Technology matters too: in Start-Stop cars, an EFB cannot be replaced with a conventional battery. The options at the same level are in the "Equivalents" section of this page. A direct equivalent needs what this N105 offers: 394×175×190 mm, positive on the right, the same Ah and CCA and EFB technology.

It is the AGM of the same case: more cold cranking, faster charging and far more resistance to cycling and heat than the N105. Compared with the N105 it has the same Ah and cranking power. It costs 9,10 € more. Mandatory if the original was AGM; in a car without Start-Stop the N105 does the job and AGM is a bonus in cranking and durability, not a necessity.

A technology step up: sealed AGM, with stronger cranking and a noticeably longer life than the N105 when the car draws a lot of power. Compared with the N105 it has the same Ah and cranking power. It costs 9,10 € more. Choose it if your car required it from the factory or if you want the longest-lasting battery for this size; for normal use without Start-Stop, the N105 is plenty.

Renault Energy TCe, Peugeot/Citroën PureTech, Fiat MultiAir, Hyundai/Kia ISG and Ford EcoBoost are examples of basic Start-Stop (no regenerative braking) fitted with it from new. An EFB (Enhanced Flooded Battery) is flooded lead-acid, but reinforced: carbon and polyethylene additives in the plates and thicker grids. It handles more cycles than a conventional battery and copes better with deep discharges, though less well than an AGM. EFB is the right technology if your car came with one from the factory (moving up to AGM is optional and the gain marginal). If it came with an AGM, fit an AGM instead.

It is not strictly necessary on most cars, because the alternator detects the change and adapts the charge. The advisable step is to register it via OBD: the charging profile is optimum from the first minute and the battery lasts longer, especially on brands with sophisticated BMS (BMW, Mercedes, Audi, Volvo, Land Rover). Without registration the car starts normally; the alternator simply takes a few days to adjust the profile. Any garage with an OBD scanner can do it in a few minutes. If you prefer to do it yourself: VCDS / Carista (VAG), Bimmercode (BMW) or iCarsoft.