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Tag Archives: Battery Connections

How to treat corroded battery terminals

Corroded battery terminals can prevent your vehicle from starting. You could have so much corrosion around your battery connections that the resistance is stopping the current from getting through to start your vehicle.

Battery corrosion is caused by hydrogen gas being released through the battery vents from the acid inside the battery. This mixture builds up over time and is the white, green, or blue tinted corrosion we see on battery terminals or cables.

Most often the corrosion occurs on the negative battery terminal, which is a sign of undercharging the vehicle’s battery. This typically happens when the alternator does not have enough time to replenish the lost battery capacity. Battery corrosion on the positive terminal is normally from overcharging. If this is what you are seeing in your vehicle, it may be best to have your alternator checked for proper output.

Once corrosion occurs, if the buildup is not too severe, the terminals can be cleaned by using a battery cleaner with sandpaper or a wire brush to loosen up the corrosion and scrub it away. Before doing this, you should turn your vehicle off and disconnect the battery cables from the vehicle. For safety the negative cable should be disconnected first, and hooked up last. A solution of warm water and baking soda will neutralize any acid on top of the battery or in the vehicle tray.

Sometimes, a corroded battery cannot be sufficiently cleaned, and it is time for a replacement. When inspecting your battery, be sure to check the condition of the case itself. If it is leaking or swollen, it is time to replace the battery instead of cleaning the corroded terminals and cables.

The best way to fight corrosion is to prevent it from ever starting. You can use a spray battery protector which is meant to prevent corrosion build-up on battery terminals and cables. Always start with a cleaned-up connection and read the manufacturer’s directions before use.

Series & Parallel Battery Connections

You’ve probably heard the terms “series” and “parallel” before. What do these terms mean and how do they influence what charger you need? When discussing batteries that are connected in either series or parallel, it is important to take into consideration the proper charger select that should be made when charging your battery.

Series Connection

To make a series connection between batteries, use a jumper wire between the negative of the first battery and the positive of the second battery. Run your positive wire off of the open connector from the first battery and your negative off of the open connector on your second battery.

In a series connection, the individual battery voltages are added together. When charging your battery, it is necessary to account for the total voltage of the string.

For example, if you have (2) 100 amp hour, 6 volt batteries connected in series, the total voltage is 12 volts and the amp hour capacity of the assembly is 100. In this situation, you would use a charger that satisfies both 12 volts and 100 amp hours. Electric golf carts often use 6V, 8V, or 12V batteries connected in series to produce a total of 36 or 48 volts.

Parallel Connection

A parallel connection is made by connecting the positives of all the batteries in the string down the line with a jumper wire, and then doing so with all the negatives. Then, connect the last positive and negative to the application.

Batteries connected in parallel increase the amp-hour capacity of the assembly, but not the voltage. A parallel battery system’s voltage is the same as the individual batteries, but it will increase the run-time for which it could power an item.

When charging batteries that are connected in parallel, it is crucial to take into account the increased amp-hour capacity when selecting your charger. A good example of a parallel connection is diesel pickup truck with (2) starting batteries connected in parallel to maintain 12 volts, but double the available starting amps and reserve capacity.


Whether it is the increase in voltage from a series connection or the increased amp-hour capacity from a parallel connection, understanding how these are different and the appropriate manner of charging your battery system is important in maximizing battery life and performance.

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