How do I adjust alternator voltage?

My alternator is undercharging the battery on the van I use for my independent locksmith business and it’s impacting my efficiency (which is impacting my overhead). Can I adjust my alternator voltage?

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Answer provided by
Laura Salvas
Answered on Apr 29, 2022
Every penny counts when you run your own business. Ultimately, if your alternator is faulty, the best solution is to have the alternator replaced or refurbished. But if you’re looking for a temporary fix, it is possible to adjust alternator voltage using diodes.
A diode is a small semiconductor which essentially tricks the alternator into thinking the voltage is lower than it is, encouraging it to increase the voltage.
You can use connectors to add diodes to the excite wire running to the alternator. How many diodes you use will depend on how much you wish to increase the voltage.
If you do this, always ensure the silver—or negative—end of each diode is pointed toward the alternator.
Diodes are inexpensive and can be purchased at an electronics store or online. Keep in mind that if a diode is faulty, your alternator won’t work as it should.
If your vehicle is on the older side, your alternator may have a manual voltage adjustment on the regulator that can be changed using a screwdriver. As this varies by vehicle, check your user manual.
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