How many volts should a car battery lose overnight?

If the motor had just been running and just switched off it should have 14.0V. Left standing with everything off overnight, it will settle down to 12.8V. After a week’s standing it will droop to 12.6V, depending on ambient temperature. After a month it should still have about 12.4 to 12.5V.

How many volts should a car battery have just sitting?

12.6 volts
When the probes touch the terminals while the car is off and the battery is resting, the multimeter display should show a reading of 12.2 to 12.6 volts (full charge). This voltage range means the battery is in good condition for starting the vehicle.

How much should a battery discharge overnight?

On average, a normal reading should range between 50 and 85 mA (it depends on the particular model, number of electronic modules and power devices that remain on after shutting down the engine). Your car owner manuals may give you the normal parasitic load for your car model.

Why is my car battery draining overnight?

This can be a result of various factors including the number one cause which is leaving headlights, glove box lights, or cabin lights on overnight. Parasitic drain can also be caused by defective fuses, bad wiring, and poor installation of a new car battery.

How much voltage drop is acceptable overnight?

If you measure the voltage immediately after the end of a drive, it should be more like 13.2, and drop to 12.7 within a few minutes as the chemical reactions in the battery slow down and stop when you stop charging it.

Why would a car battery drain overnight?

Are car batteries 12v or 14v?

A car battery is just about 12v. To charge it you need a higher voltage so the alternator puts out about 14v to do it. Most so called 12v accessories (phone chargers,etc) are designed actually work on around 14v in reality, because that’s the voltage in the cars wiring loom when it’s running.

Can a car battery lose charge overnight?

A slow battery drain when everything is off is called a parasitic power loss. Since the alternator isn’t generating vehicle electricity, the problem component pulls from the battery, slowly draining it overnight until your vehicle won’t start.