How to Jumpstart a 24v With 12v Battery?

Batteries in automobiles are used to supply electrical energy to various sections. More importantly, you won’t ignite your vehicle if its battery is not functional. More giant trucks use larger batteries rated at 24 volts. By comparison, small trucks and saloon cars use standard 12 volts batteries that fit the slot in their engine compartments. So what is a battery?


A battery is designed to store electrical energy. The internal construction consists of electrochemical plates with negative and positive terminals on opposite ends. You’ll find that a 12v battery has six electrochemical cells. The potential difference (volts) between any two plates is typically 2.1 volts. A 12 volts battery has six plates, each holding 2.1 volts which translates to 2.1×6=12.6V. Let’s see what a battery voltage is.

Battery Voltage

The electrochemical cells inside a battery are in chemical composition. As a result, the chemical energy stored by these cells can be transformed into electrical power. You can measure a battery’s potential difference in volts between its negative and positive terminals. Imagine a battery being a pipe, and the voltage is the pressure exerted by the water inside the pipe. To make water (current) flow out of the pipe (battery), you require pressure (voltage) to supply electrical current to your car or device.

Tapping Power From the Battery

To utilize the energy stored in a battery, you can tap across its positive (anode) and negative (cathode) terminals. More importantly, you should always connect the battery’s negative terminal to the chassis. Customarily, batteries come in different designs and sizes. However, batteries with high voltage ratings can supply more energy than smaller ones. Standard car batteries measure 12 volts, while more giant trucks use 24 volts.Tapping Power From the Battery

You can obtain higher voltage, say 24 volts, by stacking two 12 volts batteries in series. Electric cars, for instance, utilize battery voltages from 300 to 700 volts. No electrical current will flow from a battery terminal when you disconnect it from an existing circuit. When you connect a battery to an external device, you create an imbalance in the battery’s conductive material.

Battery State of Charge (BSOC)

The battery’s condition in use depends on the battery state of charge (BSOC). It is a factor that defines the fraction of the available energy over the battery’s total capacity. If a battery has degraded due to aging, its state of charge will fall below the nominal 12v rating. For instance, if a battery of 200Ah capacity is at 50% state of charge, it means its usable capacity is 50% of 200=100Ah.Battery State of Charge of Standard car batteries

Standard car batteries have their capacities (Ah) ranging from 35Ah-100Ah. Many factors may cause a battery to fail, hence requiring jumpstarting. Firstly, a car battery ought to be at full charge (12.6 volts) regardless of whether it is in use or not. Again, the electrochemical plates must always be immersed in the electrolyte. Other factors that lead to battery damage include storing them in cold, moist environments and irregular charging/discharging cycles.

How to Jumpstart a 24 Volts Battery with 12 Volts?

Since a 24 volts battery has a bigger voltage capacity than its 12 volts counterpart, it is impossible to jumpstart it directly. However, you can combine two smaller batteries to achieve that.How to Jumpstart a 24v With 12v Battery

Required Materials

Here’s what you need to get started:

  1. Two 12 volts batteries
  2. A pair of 10mm jumper cables (max 2 meters long each)
  3. Six heavy-duty crocodile clips
  4. A ½ a meter long (10mm) linking cable
  5. A piece of sandpaper
  6. Protective hand gloves
  7. A wrench
  8. Penknife

Getting Started

If your truck’s battery requires jumpstarting, it means the battery no longer supplies sufficient voltage. Here’s how to jumpstart your 24 volts battery using two 12 volts batteries. First, set up your materials in this order:

Step 1. Wear Protective Hand Gloves

Wear your protective gloves as protection from battery acid or getting your fingers pricked by sharp objects.

Step 2. Prepare the Materials

  • Cut two cables of 10mm cross-sectional area
  • One should be red and the other black
  • Strip off 10cm of insulation from either end of each (2m) cable
  • Attach the crocodile clips to the stripped ends using a pliers
  • Attach crocodile clips to either end of the shorter ½ meter cable
  • Use a piece of sandpaper to clean the battery terminals

Step 3. Position the Vehicles

Park the truck using 12 volts battery to the stalled truck whose 24 volts battery requires jumpstarting. Now, if the two vehicles have their battery compartments by the side, you need to park them side by side. However, if their batteries are placed beneath the hood, then park them face to face.

Step 4. Connect the Links

Access the two 12 volts batteries in the vehicle using 12 volts set of batteries. Use the shorter 10mm cable to link the two batteries in series. To do this, clamp the crocodile clip to the negative terminal of one 12V battery. Connect the other end to the positive of the second 12v battery. Use a wrench to isolate the battery terminals from the vehicle.

Step 5. Make the Parallel Connections

Connect the red jump lead cable from the positive 12v battery terminals to the positive terminal of the 24v battery. Connect the black lead cable between the negative 12v batteries in series to the negative terminal of the 24v battery. Set the vehicle using 24v to neutral. When you complete connecting, ensure they grip tightly onto the battery

terminals. Ignite the truck, and once started, disconnect the cable jumpers. That’s it


Batteries play a crucial role in automobiles. If used as intended, a battery can last over a decade while in use.