How to Convert 12V to 24V

by Brandy Alexander Images

Most car, truck and boat electrical systems run on 12 volts DC, but increasing that to 24 can have a few distinct advantages. Increasing voltage means decreasing current, and as current is the main determining factor in wiring size, increasing voltage means decreasing wire size. This means that doubling your voltage output to 24 volts will allow you to run wire gauges that are half the size (and cost) of traditional 12-volt systems. Making this conversion is a simple task, but may require the replacement of your electrical loads.

Step 1

Mount the two batteries as near together as possible and ensure that they are securely fastened to prevent movement when the vehicle is in motion.

Step 2

Connect the negative terminal on the first battery to the vehicle's ground. You can usually do this by connecting the opposite end of the wire connected to the negative terminal to the engine, gearbox or chassis.

Step 3

Connect the positive terminal of the first battery to the negative terminal of the second battery with a length of battery cabling as short as possible to accomplish this connection.

Connect a length of battery cabling to the positive terminal on the second battery, with the other end connected to your starting motor. Other appliances can also be connected to the positive terminal on the second battery as well, which will be putting out 24 volts, as when batteries are connected in series their voltage is added, with their capacity remaining the same.


  • Check to ensure that all the electrical loads drawing power from the batteries can handle 24 volts, and replace any if necessary with models that are capable.
  • Select two 12-volt batteries from the same manufacturer, with the same specifications, for best reliability.
  • Wire gauges can be halved when switching from 12 volts to 24, which can save a lot of money when installing new systems.


  • Make sure that your loads can handle 24 volts to ensure the most efficient performance of the loads.

Items you will need

  • Two 12-volt batteries
  • Battery cables

More Articles