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Can a battery tender charge a dead battery? 

 September 19, 2021

By  Phil Borges

How often have you been in situations where your car battery has died, and you don't know what to do? There is not much to worry about because there are some things that can be done. One of the questions most people ask themselves when they've got a dead battery is, "can a battery tender charge my dead battery?" The answer is yes! Why not take advantage of this article for tips on how to use one correctly and increase the life span of your vehicle's engine.

Will a battery tender charge a dead battery?

It is best to keep in mind that a car's battery will gradually lose its charge over time. It's important to know what you should do when your car doesn't start because it has been sitting for a long time and the battery needs a jump start or if you are out on the road and your engine suddenly stops running, leaving you stranded.

In these cases, there is no other option but to call roadside assistance with jumper cables or find someone who can give some help. But before that happens, a battery tender can be very useful.

What is a battery tender?

Battery tenders are an electrical device that helps to recharge your vehicle's dead battery. This handy tool can prevent the corrosion of car parts, make it possible for you to start your engine immediately, and maintain your vehicle all year long without causing you additional trouble.

The main role of a battery tender to the dead battery is to bring charge and voltage back into the battery. This process will take some time, but in the end, you can probably get the dead car start.

With a battery tender, you can recharge your batteries back up safely without causing explosions or harm to your vehicle's electronics while charging it with an auto battery charger.

For example, one type of Battery Tender will keep a dead battery for at least 35-45 hours or preferably more and about 20-30 hours with the help of some other brand of Battery Tender.

Generally, these chargers cannot charge an already-depleted battery. Cars need a specific voltage to operate. If the car battery is not charged, it will lose power over time and eventually stop working.

What are the common types of battery tenders for a dead battery?

A good battery tender will include smart chargers that stop charging once the battery is fully charged, which can be very helpful when a person who doesn't have much time. There are those that need to be looked into before buying because some tenders cannot charge an already-depleted battery in case of emergency.

There are many different types of these devices on the market with various parts and features to consider.

You must ask what factors you should be looking for in a good battery tender. There are several different ones on the market, but they all basically fall into three categories: smart chargers with automatic shutoff when fully charged, trickle chargers that do not have an automatic shutoff, and conventional chargers with an automatic shut off to prevent overcharging.

smart charger with automatic shutoff will cost you more but is well worth the investment for your car's charging system. These chargers have intelligence in them that allows them to sense when full charge has been reached and then automatically shuts off, preventing any damage from coming to the battery or charger itself. They are also equipped to charge a battery either on the hook under your hood or in your trunk.

A trickle charger is just that: a device with a low voltage output. Thus it "trickles" power into the system over a longer period of time. While this type of tender can work well if you are going to be gone for an extended period of time, it isn't recommended for daily use.

conventional charger works much like the one that you have at home for your television or computer. It has an automatic shutoff to prevent overcharging but cannot provide enough power to get a car running again if its battery is dead and needs jumpstart cables from another vehicle.

Experts also recommend that you read the troubleshooting guide in your owner's manual. If your car still won't start with a jump from another vehicle, then it is time to consider replacing the battery.

How to use a battery tender correctly?

First, disconnect the battery's negative terminal.

Second, connect the positive terminal of the battery tender to the positive terminal of the disconnected car battery.

Third, connect one end of alligator clips to another end of the positive cable in parallel or series.

Fourth, connect a jumper cable to the opposite end.

And finally, you can start charging your battery with a battery charger or any other source.

The manufacturer of your chosen battery tender may inform you that you can leave it connected to the battery for as long as you want. However, it is always better to remove the tender once your battery is charged. Leaving it in place can cause overcharging, resulting in excessive and irreversible damage to your car battery, affecting starting ability and longevity.

To summarize: Always make sure that you use a multimeter to monitor the voltage level of your car battery before you decide to use a battery tender. If you do not have a multimeter, then simply touch the probes of an unused jumper cable to both ends of your car battery and wait for a few seconds. If the reading on the multimeter is above 12.70 or more, your battery is charged enough, and you should remove the battery tender.

If your car does not start after several attempts, then detecting a low or dead car battery is sufficient to indicate that it's time to use a battery tender. However, there may be other reasons for your car not starting, which are independent of the condition of the battery.

About the author

Hi, I'm Phil Borges.. thanks for reading.. My wife says I can't shut up about batteries so to save my marriage I've started this blog .. where I'd be ranting about batteries! Please leave a comment if you have any questions, I'm happy to help!

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