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Got a question for our Porsche technician? Email us edito[email protected]tal911.com With regards to my 996 Turbo, the new battery carrier and battery are all fitted and the car does seem to start better with an 85ah battery fitted rather than the 71ah it came with – I know it should have had at least an 80ah on there, buyer beware! So, a quick question: would a lower power battery have any effect on the way the car runs? Obviously the car draws ‘X’ amount of power from it as the engine runs, but would it affect engine performance or cause issues elsewhere with spark, timing, ignition and so on?
In short, the answer is no. A smaller battery does not affect the way the car runs. A car’s battery is mainly for starting the engine as the starter motor draws a high current for cranking.
The amps and voltage are regulated by the alternator to maintain correct voltage, not the battery. Therefore, once the engine is running, voltage will be maintained around 13.5 to 14.5v depending on electrical load and battery charge status.
If you think about it, a completely flat battery can still be jump-started and the car will then run fine. As long as the alternator is doing its job and regulating the voltage then the car will run the same, regardless of battery size. A bigger battery will mainly assist on starting your 911 from cold as they will have a higher coldcranking amps capacity.