Odyssey ODX-AGM34 · Car battery 68Ah 850A AGM

Yes: the ODX-AGM34 from Odyssey uses AGM (Absorbent Glass Mat) technology, a sealed lead-acid battery whose electrolyte soaks a glass-fibre mat. Its advantages: more charge/discharge cycles than a conventional battery and better heat tolerance. It is also required in cars with advanced Start-Stop and regenerative braking.

Yes: being AGM, the Odyssey ODX-AGM34 is designed for Start-Stop cars. AGM batteries support advanced Start-Stop and regenerative braking thanks to their higher cycle count. It works once fitted; on most modern cars, registering it via OBD is advisable so the alternator applies the optimum charging profile. The general recommendation is EFB for basic Start-Stop and AGM where there is regenerative braking (it handles more cycles), unless the car manufacturer says otherwise.

Steps: 1) switch off and remove the key; 2) find the battery (bonnet, boot or under a seat); 3) undo the negative (−), then the positive (+); 4) remove the clamp and the old battery; 5) fit the new one facing the same way (positive on the left) to match the polarity; 6) connect the positive (+) and finally the negative (−). Allow 15-30 minutes and a 10 mm spanner. If the car keeps its battery in the boot or under a seat, it can take up to twice as long. Before you start, check the car handbook: the manufacturer's procedure always comes first. Our full step-by-step guide is on the blog.

As a guide, you can expect the Odyssey ODX-AGM34 to last 5 to 8 years in mild-climate car use with Start-Stop, although the real figure may be higher or lower. 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.

Measure your car's battery tray first; if the battery exceeds it by even a millimetre, the hold-down clamp may not close. Length × width × height: 277x173x201 mm. Height is measured to the top of the terminals.

On the Odyssey ODX-AGM34, the polarity is positive on the left. To check, stand the battery in front of you with the terminals nearest you: the positive (+) is the one with the red ring. Compare it with the battery you are replacing: if it does not match, cables must be lengthened or the system reconfigured, with a risk of short circuit.

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)). The ODX-AGM34 typically fits a wide range of European vehicles thanks to its standard DIN case format. If our table and the car handbook disagree, go with what the manufacturer says.

Not just any technology will do: an EFB cannot be replaced with a conventional battery in Start-Stop cars. The "Equivalents" section further down lists the recommended alternatives. Interchangeable means the same dimensions, same polarity, same Ah and same CCA; for the ODX-AGM34, 68 Ah (850 A cranking).

It has the same dimensions, voltage and technology as the ODX-AGM34, although it is not a manufacturer-approved equivalent. Compared with the ODX-AGM34 it has the same Ah and cranking power. It costs the same. Check the positive terminal side and the original capacity before ordering; otherwise it is a straight swap.

Many more charge/discharge cycles than a conventional battery and no leaks: that is what AGM technology brings, with the electrolyte absorbed in glass fibre. Hence it is recommended for advanced Start-Stop with regenerative braking, such as BMW EfficientDynamics, Mercedes Eco, Audi MHEV, Land Rover ECO or Volvo i-Stop, and it handles tilting, vibration and extreme temperatures better than an EFB. The Odyssey ODX-AGM34 has a capacity of 68 Ah.

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). 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. Even if you do not register the Odyssey ODX-AGM34, the car will start correctly; the profile adjusts within a few days.