Battery tender: A wonderful way to extend the life of your automobile’s battery.

About Battery tender, Have you ever left your vehicles for weeks and months without cranking? 

What happens when you come back?

You may not be able to start your vehicle in one go because the battery must have drained. Isn’t it irritating to jump-start your vehicle in such a situation?

So, what can you do?

The best solution is to keep a battery tender with you or in your garage.

What is battery tender?

Battery Tender is the name of a vehicle charging and maintaining device brand introduced by Auto tech company Deltran

Battery tender devices and others like them work as battery chargers and maintainers for automobiles, sustaining the battery’s charge for long periods when it is not in use. 

Generally, when not used, all batteries tend to discharge, leading to complete drainage at the end. 

And as the battery loses its charge, its tendency to get damaged increases. With a battery charger and maintainer, you can extend your automobile’s battery life by keeping it always charged.

You can call a battery tender a trickle charger, too, since it can charge small batteries. 

In contrast, for larger batteries, it work as a maintainer that continuously charges the battery as it drains, keeping the battery fully charged.

A battery charger and maintainer can charge ATVs, dirt bikes, lawnmowers, and motorcycles. However, it can only maintain the car batteries but not charge them.

If you are using a battery tender, you only need to plug it into a regular power outlet in your home. 

Remove your vehicle’s battery and connect its two terminals with the battery tender as you do while you jump start. Keep the battery installed if the power outlet is close to the vehicle.

Battery tenders are of different types. You may need to turn on some chargers and maintainers while others start charging when you connect the battery. 

In these devices, the battery remains connected to the charger and maintainer. However, it will charge the battery only when the charge percentage drops below 100%.

A battery maintainer

A battery maintainer

Trickle charger Vs. Battery tender: What’s the difference?

Most motorcycle owners use battery tenders for their vehicles during winter as they rarely ride.

 On the other hand, car owners tend to use trickle chargers when they leave their vehicles unused for long.

Here is a table describing the difference between a battery tender and a trickle charger, which helps you know why they make such a decision.

Trickle chargerBattery tender
Charges a battery to 100 percentCharges a battery to 100 percent
This charger does not stop charging and keeps sending voltage regardless of the battery’s charging state, which can harm batteries over time. 
On the other hand, some trickle chargers have a SMART mode that senses the battery charge and adjusts the voltage flow like a maintainer.
Battery maintainers or float chargers shut off charging once the battery becomes full. 
If the battery starts draining, it will kick off again. Due to this feature, you can use a maintainer with your vehicles when leaving them for long periods.
Although you can connect these chargers for extended periods for slow charging, they cannot maintain a healthy charging level.Safe to use for an indefinite period. Battery maintainers are ideal for people living in cold and long winter locations.
It would be best if you had a trickle charger when the battery is completely dead.A battery maintainer helps keep a battery charged for long periods.
An automotive mechanic holding jump leads

An automotive mechanic holding jump leads

Why do you need a motorcycle battery tender?

There are mainly two reasons.

To prevent parasitic drains

Modern motorcycles come integrated with various new technologies like GPS, alarm systems, diagnostics, etc. 

All these systems continuously draw a very small current from the battery even when the ignition is OFF. 

If left for long periods, it may lead to complete drainage of the vehicle battery.

To avoid such situations, you can use a motorcycle battery tender. 

The tender identifies when the battery is below its full charge voltage and starts charging till it again becomes green. 

As soon as the battery charges, the tender shuts off. The tender keeps on repeating this process automatically as and when required.

To prevent sulfation:

If you live in a very cold region, park your motorcycle in the garage during off-seasons. In such situations, the battery loses its charge over time.

 This phenomenon is common in all lead acid batteries and tends to self-discharge with time.

Due to this self-discharge, the sulfation process starts in the internal plates.

 The sulfation results in the loss of battery capacity and cracking amps. You can constantly charge your battery through battery tender and avoid sulfation.

Using a digital multimeter to measure the voltage

Using a digital multimeter to measure the voltage

How can you use a battery tender?

There are several models of battery tender. Thus, we consider a battery tender of 12V @ 1.25A to explain the use process. 

We assume we are using this tender for a 12V 6-cell automobile battery.

Follow these steps to charge the battery when it is still in the vehicle:

  • Safety comes first; thus, wear eye protection and proper clothing. Keep soap and water ready near you if acid comes in contact with your skin accidentally. Always work in a well-ventilated area. Also, ensure that somebody is near you so that he can call for help in case of an accident.
  • Now, put the charger as far as possible from the battery (according to the length of the cable).
  • Position all the vehicle’s moving parts, like fan blades, hood, or pulleys, away from the AC/DC cords of the charger. Do this while keeping the charger in the OFF position only.
  • Find the battery’s Positive and Negative terminals. Also, find out which terminal is grounded or connected to the chassis.
  • Now, connect the clips of the battery charger properly based on the vehicle’s battery terminals.
  1. If the negative battery terminal is grounded, connect the Red or Positive clip to the battery’s Positive or ungrounded terminal. Then, connect the Black or Negative clip to the vehicle’s chassis area, keeping it far away from the battery (try to find a heavy gauge metal part/engine block). Keep the Negative clip away from the carburetor or fuel lines.
  1. If the battery’s positive is grounded, connect the negative or Black clip of the charger to the ungrounded battery terminal. After that, connect the positive/Red clip to the engine block or vehicle chassis far away from the battery.
  • After connecting everything properly, plug the charger into the power outlet and turn on the charger. Your battery will start charging while it gets charged. Note the following:
  • If the battery’s voltage is less than 3 volts, the tender will not start automatically. The charger works when the battery at least produces 3 Volts.
  • Sometimes, a normal 12-V lead acid battery produces less than 9V output when not being charged or not supplying current; it means the battery is defective and needs replacement.
  • After observing this, you will find status indication lights turned on. Here is what they mean:
  • 未勾选Red Light Flashing: This tells that the charger has AC power and the microprocessor is working fine. If the flashing continues, it indicates that the battery’s voltage is less than 3 Volts or ring terminal connections are loose.
  • 未勾选Steady Red Light: It shows the connection between the charger and the battery is fine. The charger is charging the battery. This light will remain steady until the charger charges the battery fully.
  • 未勾选Green Light flashing: When the red light is On and the Green light flashes, it indicates that the battery is charged more than 80%, and you can use it. However, it’s advisable to continue charging the battery until the green light becomes steady.
  • 未勾选Steady Green Light: This indicates that the battery is fully charged. However, there is no need to remove the battery tender if you are not using your vehicle. You can leave the tender for an indefinite time.

Whatever product you use, read all the manuals and their instructions. Sometimes, some products come with particular instructions for use. 

So, it’s better to familiarize yourself with the products to use their features fully.


Once you can use the product, you can utilize your battery to its full potential for many years. 

Battery chargers and maintainers are wonderful products to ensure the long life of your vehicle’s battery. 

If you need help with the cables of these chargers and maintainers, contact Cloom. 

We are experts in customs designing and manufacturing all cable assemblies and wirig harnesses.