When Fully Charged, How Many Volts Should A Car Battery Have? Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts.
Table of Contents
What voltage should BMW battery be?
Check the voltmeter reading. It should be around 12.45 volts, but not more than 12.7 volts. If the reading comes in below this range, it might be time to replace your car battery.
What should the BMW alternator voltage be?
That is, a fully-charged battery at rest should read 12.6 volts, but when the alternator is charging the battery, it should read about 13.5 to 14 volts.
How do I check my BMW battery voltage?

What type of battery is in a BMW 750li?
DieHard Platinum AGM – Battery: H8 Group Size, 900 CCA, 1000 CA, 160 Min Reserve Capacity, For High Electrical Demands (Part No. H8-AGM)
How do I know if my alternator is bad on my BMW?
- Dead Battery.
- Slow Or Malfunctioning Accessories.
- Dashboard Warning Lights.
- Performance Issues.
- Trouble Starting Or Frequent Stalling.
- Growling Or Whining Noises.
- Smell Of Burning Rubber Or Wires.
- Electrical Issues.
Is 15v too high?
So, to answer your question, Yes, 15 volts is too high. Most car alternators, that normally recharge your battery after every start, and provide power while the engine is running, are normally voltage regulated to about 13.8 to 14.0 volts.
Is 15 volts too high for an alternator?
A good alternator should maintain battery voltage between 13.9 and 14.8 volts (14.2 is optimum). Even worst-case, with all accessories turned on, there should be at least 13 volts at the battery.
What voltage is too low for an alternator?
A good alternator should produce about 13.5 to 14.5 volts with the engine idling. If the voltage reading is low (12.5 volts or less), it indicates a charging problem but does not tell you what’s causing it. That’s why bench testing is so important.
How do I know if my BMW needs a new battery?
- Dimming headlights.
- More frequent need for engine revving or jump starts.
- Takes longer to start the engine when you turn the key/push the button.
- Unusual power fluctuations.
What happens when BMW battery is low?
An engine that refuses to crank or start. The lights won’t come on. Intermittent starting, i.e., one day your vehicle will start up fine, and the next it refuses to start, indicating an unreliable battery charge. Your BMW struggles to crank in cold weather.
Why does my BMW car battery keep dying?
One of the electronics on your car drains too much power or does not go into sleep mode. Faulty alternator. Old battery.
Does BMW need special battery?
Conventional car batteries can be used for BMWs with average power requirements. Therefore, you don’t need a specific BMW car battery if your car doesn’t have sophisticated car accessories or a start-stop system.
How much is a battery for a BMW 750?
The average cost for a BMW 750Li battery replacement is between $431 and $456.
Can I replace BMW battery myself?
Many people wonder though, whether BMW battery replacement and registration is a simple DIY process or has to be done by an expert technician. We say: you can definitely handle the replacement on your own!
How can you tell if its the battery or alternator?
Jumpstart your car. If you can turn the engine on, but it dies shortly thereafter, your car alternator likely isn’t able to charge the battery. On the other hand, if you jumpstart the car and later on it fails to start on its own, it’s likely a dead battery.
Is it my alternator or battery?
If the engine starts but dies immediately, your alternator probably isn’t keeping your battery charged. If a jump starts and keeps your car running, but the car can’t start again off of its own power, a dead battery is probably your answer.
What are signs your alternator is going out?
- Dim or Overly Bright Lights.
- Dead Battery.
- Slow or Malfunctioning Accessories.
- Trouble Starting or Frequent Stalling.
- Growling or Whining Noises.
- Smell of Burning Rubber or Wires.
- Battery Warning Light on Dash.
Is 14.7 volts too high?
The battery terminal charging voltage must be less than 14.7 volts to prevent excessive gassing. Charging voltages over 14.7 volts can prematurely dry the battery by boiling out electrolyte, and increase risk of a battery hydrogen gas explosion.
Is 14.7 a good battery voltage?
The ideal car battery voltage with the engine running is between 13.7 and 14.7V. With the engine off, you should get a reading of 12.6 volts.
Why is my car battery showing 13 volts?
Nominal charge is 12.6 volts (half full) Fully charged is 14.2 to 14.4 volts. So if you are at 13 volts this is a somewhat charged battery. Put it back on the charger.
Why is my car running at 15 volts?
If the voltage stays at 15.5 volts after the car’s been running awhile, your battery could have a shorting cell, therefore it’s bad. If your battery tests good , your regulator circuitry isn’t functioning properly. If you have an external voltage regulator try replacing it.
Is 14.8 V too high for a car battery?
For a car with a 12V engine, the normal value before starting is between 12.2V and 12.8V, and it should not exceed 14.8V after starting.
Why is my car battery at 15 volts?
If the voltmeter reads between 14-15 volts then the battery is normal. But if the battery reads over 15 volts or less than 13 volts, then there might be a problem with the alternator. The alternator is over charging the battery or not giving enough charge to the battery.
Is 14.7 volts overcharging?
If your battery has a charge between 12.4V and 12.7V, your battery is fully charged and ready to run. If your voltage is below 12.2V, it needs to be recharged. Take a 30-minute drive on the highway or pick up a charger to bring the voltage back up. If your voltage is higher than 12.9V, the battery is overcharged.