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The battery on my car was just over 7 years old. I had noticed that the low battery warning had come on several times, so I thought it was probably time to replace it. If possible I wanted to fit a battery with a higher capacity to support a dashcam with parking mode, which would drain the battery. My car also has a tracker that will add to the strain on the battery.

The battery is located in front of the windscreen under the bonnet. To access it, open the bonnet. The large plastic tray between the bonnet and ‘frunk’ boot space can be removed by pulling up on the cover with a hand in each of the holes shown here:

Once the front of the cover is lifted up, the whole cover can be pulled forward and away from the car.

On my car the Original battery is a ‘BANNER’ branded 80ah capacity unit. There are 2 brackets holding the battery in place. The first is secured with 2 13mm bolts, shown below already removed.

The battery tray is wider than the existing battery, suggesting that there are potentially larger batteries that will fit. Note the extra hole for securing the wider battery in place.

After a bit of research, I found that the Bosch S5 A13 AGM 95AH battery will fit. Here are the old and new battery shown side by side:

The battery terminals can be removed with a 10mm spanner:

Once the batteries have been swapped, I found that the clock had reset. The 991 supports clock synchronisation with GPS time via the build in Navigation. this can be enabled in the menu system, instructions are in the owner’s handbook.

Final note: Although many owners have reported that it is not necessary, if you have access to Porsche PIWIS diagnostics, there is a screen where you can configure the on board charger with the battery’s characteristics, including total capacity, chemistry and battery serial number. Please leave a comment if you would like me to write an article on how to do this.