Can I use a battery charger as a battery tender?

Asked By: Jabbar Tenhaaf | Last Updated: 14th May, 2020
Category: automotive road side assistance
4.3/5 (841 Views . 34 Votes)
So the short answer is 'Yes, you can leave the Battery Tender® Plus (BT Plus) battery charger connected to a battery even when it is being used to provide power to another appliance.

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Considering this, what is the difference between a battery charger and a battery tender?

The difference is smarts. A trickle charger provides a constant current all the time. It does not know whether the battery is charged or discharged. A battery tender is smart.

Similarly, how do you hook up a battery tender to a battery? Place the battery tender aside. Place the red (positive) battery terminal to the positive of the car battery and secure with the adjustable wrench. Place the black (negative) battery terminal to the black negative of the car battery and secure it with the wrench. Make sure the connections are tight and secure.

Similarly, it is asked, how long does it take to charge a battery with a battery tender?

It is not an exact science, since tenders taper off as the battery voltage rises. 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.

What does a battery tender do?

It's a device that plugs into a standard AC outlet and transfers power in the form of amps to your 12 V battery to keep it operational over long periods of inactivity. Battery Tender battery chargers are essential if you have seasonal vehicles that sit for months without being used.

31 Related Question Answers Found

Can a battery tender ruin a battery?

On older vented batteries, the electrolyte could cook away, leaving the plates exposed and ruining them. Float or maintenance chargers such as a Battery Tender keep the battery charged without the risk of damage.

Is it OK to leave a battery tender on all the time?

The Best Time to Use a Battery Maintainer
After all, leaving a battery charger connected to a car for months will overcharge the battery, but leaving a battery maintainer connected for that long is fine because charging will simply stop once the battery is full.

Is a battery tender worth it?

This is too small to re-charge a low or dead battery, but enough to maintain a charge. When the battery is full, it stops charging to prevent over-charge. If you plan on not using your battery for an extended time, a trickle charger is a good idea. Battery tenders aren't as good.

Does Battery Tender extend battery life?

Battery tenders should actually extend the life of a battery as they prevent lead sulphite from depositing on the electrodes (this happens naturally as the battery discharges).

Can a completely dead battery be charged?


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. Most of the time, you don't even have to remove the battery from your vehicle.

Does trickle charging reduce battery life?

First, continuous trickle charging of a full battery can cause plating of the metallic lithium, which reduces stability in the long term and can lead to system-wide malfunctions and reboots. Secondly, it leaves the battery at the higher stress voltage when at 100 percent, as we just mentioned above.

Can you charge a dead battery with a trickle charger?

The alternator of a car is responsible for maintaining a healthy battery, but it can't recharge a dead battery. But, a trickle charger definitely could charge a dead battery. Although it will take a long time for it to bring a dead battery to an acceptable level of charge.

How much does it cost to run a battery tender?

You figure $0.11 per kW-h, so about $0.054 in a month for 24/7 operation. The maintenance charge can fluctuate up to about 100 mA, so I figure a peak of $0.10 in a month. I have 3 Battery Tender Waterproof units running during the winter and my electricity bill is normal.

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.

How do you trick a smart battery charger?


Try hooking the dead battery in series with a good battery with a pair of jumper cables then attach the charger clamps. You will fool the battery charger into thinking it has one low charge battery. After you get up to your minimum required battery voltage, remove the good battery.

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).

Is it OK to charge car battery while connected?

You can leave your battery connected when charging if you are using a trickle charger which is designed to keep your battery at a certain level of charge for extended periods. If you are using a full charge then it is best not to keep your battery connected while still connected for safety reasons.

How do you check if a battery tender is working?

The best way to test a tender (or charger for that matter), is to use a known good battery, and stress it using a load checker then read the output of the battery, then connect the charger and read the output of the battery. A fully charged battery will not draw power from a tender. A stressed battery will.

What is a battery charger maintainer?

Unlike chargers, which are designed to charge your batteries completely, maintainers are designed to supply a small trickle of electricity to your batteries over a long period of time. This trickle charge is enough to counteract self-discharge, but not so large that it threatens to overcharge your batteries.

Who makes the best battery tender?

This battery charger includes a range of great features, including reverse polarity protection, a 4-step charging program, and a safety timer.

The 5 Top-Rated Battery Chargers.
Editor's Picks Brand Rating
Best Overall Battery Tender Junior Battery Maintainer 4.6
Runner Up NOCO Genius G1100 Battery Maintainer 4.2