Can a battery tender charge a dead battery?

Asked By: Abdeljalil Cuende | Last Updated: 28th January, 2020
Category: automotive road side assistance
4.3/5 (4,961 Views . 37 Votes)
A completely dead battery should take at least 35-45 hours or more with a Battery Tender Junior (0.75 amps), and 20-30 with a Battery Tender Plus (1.25 amps). Unfortunately, these chargers cannot begin to charge a fully depleted battery. They need to sense a certain amount of voltage before they can function.

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Considering this, can a completely dead battery be recharged?

A car battery is considered discharged when the voltage drops below 12 volts. While your vehicle's alternator can keep a healthy battery charged, it was never designed to completely recharge a dead car battery. These charging devices are designed to safely restore a dead battery to full charge.

Likewise, how do I know if my battery tender is charging? If the battery is fully charged, then the Battery Tender Plus battery charger's green light will be on. Once the AC power is removed from the Battery Tender Plus battery charger, the green light will go out and the charger not have any effect on the battery.

Likewise, people ask, how long does it take to trickle charge a dead battery?

24 hours

How do you bring old batteries back to life?

Bring Dead Lead Acid Battery to Live Again

  1. Step 1: Preparing the Battery. 3 More Images.
  2. Step 2: Fill the Water Inside the Battery.
  3. Step 3: Mix Water With Acid and Charging.
  4. now pull the wasted water from the top of 3 holes by the syringe and let the battery charging.
  5. 39 Discussions.

35 Related Question Answers Found

Can you restore a dead car battery?

Usually, a jump start, booster pack, or battery charger is all that's necessary to revive the car battery and get the car back on the road, but the damage has already been done. It's the accumulation of damage that leads to the untimely death of the car battery, at which point it simply will not start the car.

How do you revive a car battery that won't charge?

How to Fix a Car Battery That Won't Hold a Charge
  1. Prepare the battery. Put on the safety glasses.
  2. Perform a load test. Connect the load tester to the positive battery terminal first and then to the negative post.
  3. Remove the cell covers.
  4. Perform a hydrometer test.
  5. Test the cells.
  6. Add the treatment chemicals (optional).

Does revving the engine charge the battery?

But when your engine turns faster, the engine's alternator also turns faster. That way, all of the alternator's power can be directed to recharging the battery. Once the car starts, you CAN rev it up to charge the battery faster, but the best way to do that is to just drive it.

Why won t my car battery charger charge my battery?

The Causes of a Failed Charge
When you drive the car, the battery isn't getting recharged, i.e., there is a mechanical charging problem. There is a parasitic electrical drain on the battery, possibly caused by a bad alternator. The battery is simply old and it's time for you to replace it.

Can a car battery go dead from sitting?


A car should be able to sit parked for at least a month without the battery dying, unless it's a higher-end car with plenty of power-hungry gadgets and computers, experts say. That reaction keeps happening, but more slowly, when the battery isn't being used. That's why batteries lose their charges as they sit.

Will a car battery recharge if you let it sit?

The "self-recharging" features of batteries is most noticeable in a car battery. In some cases you can crank the engine until the battery seems totally dead, then come back an hour later and crank it again. If you let the battery rest for awhile, the hydrogen gas dissipates and the battery "comes back to life".

How long should I leave my car running to charge the battery?

If your car does start, let it run for a few minutes to help charge the battery further. Unhook the clamps in the reverse order of how you put them on. Be sure to drive your car for about 30 minutes before stopping again so the battery can continue to charge. Otherwise, you might need another jump start.

How long should I drive to charge my battery?

The longer the battery has been dead, the longer it will take to fully recharge it. However, by driving for at least a half an hour at 1,000 RPM's, you should charge your battery enough that you will be able to restart the vehicle once you turn it off.

Can you leave a car battery charger on overnight?


Even though there is no risk of overcharging with the use of a high quality charger, the battery should not remain connected to the charger for more than 24 hours. A full charge is usually achieved by charging overnight.

What should a 12 volt battery read when fully charged?

When the battery is not being charged and not delivering charge to a load, this is the rule of thumb. For a 12 volt, leadacid battery, the voltage measured between these two points should be between 11 and 13 volts. The closer the voltage is to 13 volts, the closer the battery is to being fully charged.

How many amps do I need to charge a 12 volt battery?

A medium amp output 12 volt charger would be in the range of 20 to 50 amps or so, and be used for many applications using about 100 amp hours of battery and up, or applications with a constant amp load (power supply application).

Can a car battery be too dead to jump start?


YES, a car battery can get so dead it will not receive a jump start anymore. To cut to the chase, and just before we get to the meaty stuff, a “deadcar battery is an indicator of different factors—and almost always, these occur all at the same time.

What is the difference between a battery tender and a battery maintainer?

The main difference between them is complexity as the battery maintainers contains more advanced circuitry than most battery chargers. The circuitry is used to detect the charge level to determine if the battery needs a charge and how fast to charge it.