Reasons Why a Car Battery Voltage Is Too High

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Nobody likes an overachiever and the same goes for car parts. The second most important part of a car is the battery and sometimes it can be too energetic. Just like overcharging a phone, your car battery voltage can be too high. High voltage can be damaging to your battery and your vehicle.

How do You Test Battery Voltage With a Voltmeter?

Optima Batteries 8020-164 35 RedTop Starting Battery

The best time to conduct this test is about 12 hours after turning off the car. When you first wake up in the morning, after not driving all night. The first step is to get a battery and a voltmeter. A voltmeter measures electric potential difference from two separate points in an electric circuit. A voltmeter will let you know if your battery charge is too high or too low.

To conduct the test, make sure your vehicle is off.

  1. Pop the hood and find your battery.
  2. Remove the cover over the positive terminal.
  3. Turn on your voltmeter and make sure it’s set on the “voltage” setting.
  4. Place the red sensor on the positive terminal and the black sensor on the grounded (or negative) terminal. 
  5. Check to see the reading and if it is over 12.9 volts, your battery may have excessive voltage. 12.6 to 12.8 is the ideal voltage level for your battery. Anything lower than that is a completely different set of problems.

Also Read: Why Do Car Batteries Corrode

Why is my Car Battery Voltage Too High?

There are a few reasons that can cause your battery to have a high voltage. Your battery could have a loose connection. Loose connections disrupt the flow of electricity so your battery can either be improperly charged or improperly discharged. Symptoms of a loose connector could be your car struggling to start or your headlights being too dim. Without the proper current, your car starter will not have enough power to ignite that first spark plug. If your car has trouble starting, get out your voltmeter. You may have a high voltage problem.

The alternator can also cause high voltage. An alternator is supposed to convert mechanical energy into electrical. When the alternator is faulty, the distribution of energy is not properly transformed. There are similar symptoms from an alternator as a loose connector. Your electrical systems will have issues starting and staying on. Other symptoms include your turning signals having a blinking speed problem, the car has issues staying on and your lights can be dim. That voltmeter needs to make a return because your volt problems returned.

The most unsettling symptom would be hearing a low growl coming from your hood. This isn’t a problem that will go away by just turning up your radio. A cheap trick to test your alternator is by turning on your headlights and revving your engine. If your lights brighten up as you rev your engine, your alternator is working but not well enough to maintain a constant level of brightness.

What Problems Come From a High Voltage?

The high voltage causes all kinds of problems with your vehicles. Cars are operating on a more electrical basis now with more vehicles being hybrid or electric altogether. When your battery voltage becomes too high, you can fry your vehicle’s system. Car computer systems are directly affected by the battery. With the high voltage causing inconsistent charges to the entire car, the computer system can be damaged.

Also Read: Car Battery Leaking From Top

When running test for trouble codes, the information is directly taken from the car’s computer. With a damaged computer, it can not properly alert you of problems during diagnostics. The computer system can also miscommunicate other information to the car as a whole. Improper speedometer, gas tank meter showing the wrong amount of fuel, and your dashboard lights randomly illuminating are other problems that can come from a car battery voltage being too high. 

Common DTCs to expect from a problem with a battery voltage is too high

Can I Drain my Excess Voltage?

Yes, you can drain the access voltage from your battery. The easiest way is to turn on your high beams and just allow them to stay on. Using your high beams isn’t the only way. You can also use your radio or any other electricity-draining device in your vehicle. Because we are in the generation of technology, you can just sit in your car with your phone attached to your car charger and read more articles about car maintenance on our website. This will be productive and informative.

These have been reasons why your car battery voltage is too high. Be sure to keep track of your alternator and your battery connections. Improper maintenance can short your vehicle and destroy your car’s computer. If you do not want to fry your car, call us immediately. Visit our website if you want more information on car maintenance.

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1 thought on “Reasons Why a Car Battery Voltage Is Too High”

  1. My 2015 Acadia with 40,000 km.has a battery voltage of 12.6 when started, with the voltage rising to 15 to 15.5 after a few minutes. In summer, this voltage stays in the 15V region as I drive for perhaps up to an hour or more, but in fall or winter it soon drops to 12.6 to 13.5 volts over the first few minutes of driving and stays there. I have had the vehicle for 3 years and have had to replace the AGM battery twice.
    The vehicle is driven daily, within the city most days.

    Do I have a bad alternator or a bad connection somewhere or ?



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