Is a Car or Boat Battery AC or DC?

With so many devices in cars or on boats and yachts requiring both 5V or 12V DC and 120V or 230V AC, many people wonder, are car or boat/yacht batteries AC or DC power sources.

After all, a single battery provides the power for both AC and DC devices, right? As usual in life, 'complicated' issues very often have rather simple answers ...

car in the woods w400px

Little Bit of Theory

Here is a little bit of theory regarding the meaning of the 'AC' and 'DC' abbreviations.

- AC: 'Alternate Current' - type of current that changes its direction many times per second (usually 50 or 60 times per second, hence 50 Hz and 60 Hz).

- DC: 'Direct Current' - type of electric current that doesn't change its direction.

If You check car, boat, industrial, or any similar battery, You will notice that one terminal is labeled as '+' (Positive) and another terminal is labeled as '-' (Negative) and they stay that way as long as the battery is in one piece.

Note: those rare events when the lead-acid batteries are so discharged that 'cell reversal' occurs will not be considered now :)

For short, is a car battery AC (Alternate Current) or DC (Direct Current)?

The car battery is DC (Direct Current) power source.

Thanks to modern electronics, high-frequency and high-efficiency DC/AC converters, cars, boats, yachts, trucks, RVs and other similar vehicles have 5V DC, 12V DC, 120V DC, and 230V DC sockets suitable for powering various devices, ranging from smartphone/tablet chargers to AC units and more.

And they are all powered by simple 12V battery, or battery packs consisting of the batteries connected in parallel (larger capacity) or in series (larger voltage) or both.

optima starting battery w300

Car, RV, and Home Power Inverters

People requiring 120V AC (or 230V AC) during a power outage should consider getting a power inverter or suitable power and output voltage quality (pure sine is highly recommended) and large enough deep cycle batteries, connected as required by power inverter input voltage (12V or 24V, although there are also 36V or 48V models).

The most common RV and household power inverters are those in 500 - 2000 W range with pure sine wave output.

Such power inverters may power most required home appliances during power outages, they don't require much space and they may last a very long time if used properly.

And thanks to power inverters, the battery's DC electric power is converted into 120V AC power.


Long Story Short: The car or boat batteries are DC power sources. For more information, feel free to check our recommended guides and articles:

- Watts to Amps, Amps to Watts, Amp Hours (Ah) to Watts, Watts to Amp Hours (Ah) - Units Conversions, Formulas, and Charts

- How Long Will a 12V Deep Cycle Battery Last With an Inverter

- Boat, RV, Camping and Home Appliances Wattage Chart

- How Long Does It Take To Charge A Car Battery?