Does having the "smart alternator" configured to a normal alternator void the warranty in my 2021 Ford Ranger?

Answered by CarsGuide

10 November 2021

The `smart’ alternator fitted to the Ford Ranger was designed to cap the amount of charge being fed back into the vehicle’s battery. In effect, it meant that the battery was usually charged to a lower voltage that it would have bene with a conventional alternator.

The reason for this was to extend battery life by never over-charging (and stressing) the battery, but many owners have found that the lower charge rate left them with a battery more likely to go flat when they most needed it. Many Rangers are also used for camping and therefore have a second battery fitted. That could also cause problems as the extra battery and electrical accessories often fitted to such vehicles weren’t recognised by the vehicle’s computer, leading to more low-voltage problems.

For many Ranger owners, the solution was a trip to a Ford dealer where the computer could be re-programmed to make the alternator perform in a traditional (non-smart) way and keep everything purring along. Having this performed at a dealership will not affect your warranty, but having a non-Ford technician fiddle with the charging system may not be so warranty-friendly.

I’m also informed that driving everywhere with the car’s headlights switched on causes the alternator to acknowledge the current draw and switch to a higher charging output.

Disclaimer: You acknowledge and agree that all answers are provided as a general guide only and should not be relied upon as bespoke advice. Carsguide is not liable for the accuracy of any information provided in the answers.

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