Can You Use an Extension Cord With a Battery Charger

Published on: May 19, 2022
Written by Liam Jaxon / Fact-checked by David Rowan

We are constantly facing a situation to plug in our electronic gadgets or vehicles in a more convenient location than is currently available; this may indicate that we require extra ports. When you need to use it, can you use an extension cord with a battery charger?

Certainly, you may; in fact, 75% of plug-in car owners plug their automobiles in using an extension wire. However, experienced electricians and owner’s manuals always caution consumers against long-term reliance on extension cords. 

can you use an extension cord with a battery charger

So those who are questioning, ‘can I use an extension cord with a car battery charger? can surely use an extension charger without worrying. Extension cords are commonly used in conjunction with battery chargers to keep the batteries charged, allowing you to avoid having to pull batteries to maintain their charge. 

Besides, they are also suitable for most vehicle applications, including motorcycles, bicycles, lawn tractors, trucks, snowmobiles, riding lawn mowers, boats, recreational vehicles, scooters, and others. This article supports new extension cord users by offering a safe method for charging your car battery with an extension cord. So stay with us!!

Things to Consider When Purchasing An Extension Cord

Follow the mentioned tips outlined here to find the best extension cord for your work:

Heavy Wires Carry More Power

An extension cord’s power capacity is determined by the wire thickness, not its length. Only cords of 25 feet or less should be 14 AWG thin, and extension cords should be 10 AWG thick. The power carried by thicker wires is higher. Lights, battery chargers, and stereos should all work with any cord, but using car charging and power tools like drills, saws, and vacs safely and efficiently requires power. 

Buy More Than You Need

When you are in doubt, buy the longest extension cord because short cables are inconvenient and unsafe. Multi-corded devices increase electrical resistance between the outlet and the device. Consequently, resistance can create voltage drops and power reduction. 

Know Your Device’s Amperage

It’s vital to select an extension cord that can supply enough power to the connected devices. So before you buy an extension cord, knowing the device AMP is important. We’ve provided a chart showing the relationship between cord standard and wattage to assist you in selecting the appropriate extension cord.

Cold Weather Chords Are Usually Stronger

When cords are tightly coiled on a shelf, it’s difficult to identify which ones are easiest to deal with. The only way to get a more flexible cord is to select one intended for colder temperatures. The packaging of some cables states the recommended temperature ranges; however, we’ve observed that cords listed below freezing are often more flexible.

Extension Cord Charging Preparation

Extension cords aren’t designed to be left plugged in for an extended period. Extension cables are unpleasant and tiresome, but they’re an absolute necessity. The following are the preparatory stages to charging:

  • If it is essential to remove the battery, always you need to disconnect the battery of the grounded terminal initially. Ensure that all car accessories are turned off to avoid creating an arc.
  • Ensure that the space around the battery is sufficiently ventilated while it is charging.
  • Fill each cell with pure water until the battery acid reaches the amount stated by the producer of batteries. Don’t overfill.
  • The battery’s gasses will corrode and harm any charger placed directly above it during charging. So avoid it.
  • Never place the battery on top of the charger and be left out in the rain or snow.
  • After disconnecting the AC cord from the outlet, connect and disengage DC output clips. Never let clips reach.
  • Connect clips to battery posts by twisting back and forth several times to ensure a secure connection.

How To Charge Battery with Extension Cord 

When charging a battery, follow these steps:

  1. Battery posts must be in the proper polarity at all times. Battery posts with bigger diameters than smaller diameters (POS, P, +) are more common.
  1. Glue the black negative clip to the battery’s negative post and the positive red clip to the battery’s positive post. 
  1. When making the final connection, avoid touching the battery. Chargers should be detached in the same order as they were attached, with the initial contact severed as far enough from the battery as feasible.

Current Output Switch

Extension cords are available in various lengths and power. But a suitable extension cable has a 15-amp power rating, 12-gauge wires and is third-party tested and approved. We recommend buying long enough to reach the garage but not too long to coil up. Below are different output current positions to understand:

2 Amp Position  

This position can be utilized for any size battery with a capacity greater than 10 Ampere hours (AH). This position is optimized for charging batteries with capacities ranging from 10 to 30 AH. These are the types of positions that are commonly seen in motorcycles and garden tractors.

10 Amp Position

This position can be utilized for batteries with capacities of more than 30 AH. If it is used on smaller batteries, gassing, fluid loss, and overheating will occur.

Start Position 

It provides an extra 50 Amps to the battery when starting the engine. This is an alternate position with a maximum of 10 seconds on and 3 minutes off. Switch to 2 or 10 Amp or unplug from the alternating current power supply during the off phase. 

Negative Effects of Using a Battery Charger Extension Cord

Many of you ask, “why do battery chargers say not to plug into extension cords or power strips?” All automakers and charger manufacturers caution against using an extension cord with a battery charger in a car. This is written because the cord may overheat if it is unable to carry the load, and no manufacturer wants to be held liable if you burn down your house.

The adverse effect of using extension cords are-

  • When misused, extension cables can overheat and catch fire.
  • Fires can originate from cords melting or damaged extension cords. 
  • Long wire or cord can decrease appropriate voltage supply.
  • A longer cord may overheat due to voltage reductions.
  • Reduce battery life.


Do Extension Cords Ruin Chargers?

The longer the extension cord, the harder it is for the current to pass. This weakens the charger as it travels through the cord, making the power outlet work harder. So the charger might overheat and cause an electrical fire.

Can You Plug an Extension Cord Into a Power Converter?

An extension cable works just as well with a power converter as it does with the home mains. You simply require a variety of connectors to be attached to it.

Can You Plug a Battery Charger Into an Extension Cord?

Absolutely, most auto battery chargers can be plugged into most extension cables with no problems at all. 

Can You Plug a Phone Charger Into an Extension Cord?

You can plug a phone charger into an extension cord because phone chargers consume such a small amount of current. But remember, as an extension cable has lengthy but thin wires, the voltage drop could be so significant that the phone charger will not work.

Final Verdict

It is necessary to understand how extension cords function to comprehend how accidents occur due to their use. We try to explain your inquiry,’ can you use an extension cord with a battery charger? briefly to help you out and keep you safe from a potential accident by short circuits. If the extension cord is of good quality, this should not be a problem in most situations.

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About This Writer

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Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

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