Can You Start A Car With A Battery Tender Connected?Find Out

Disclosure: This page contains affiliate links, As an Amazon Associate, I earn from qualifying purchases (at no extra cost to you). Learn More

The age of smart battery chargers has ushered in lots of possibilities in terms of how we charge and maintain car batteries. Despite the healthy competition in the battery charger market space, only a few can match the qualities of a battery tender car charger.

So to answer the question “can you start a car with a battery tender connected?” depends on what you hope to achieve: if you hope to jump-start your car, then the answer is a definite NO, and if you hope to start a very dead battery, the answer still remains.

However, nothing will occur if you start the car with your battery charger connected as long as the charger doesn’t touch any of the moving aspects of the vehicle. 

Battery tenders are one of the sorts after battery chargers in the market due to the following reasons:

Table Of Contents

Suitable For Car Batteries And Deep Cycle Batteries

Having a battery charger that can be used for both car batteries and deep cycle batteries will always be a plus – this is a feature most smart chargers lack. A typical battery tender charger is built to fast charge your deep cycle battery without having any sort of problem. Battery tender chargers have been lauded by their many users for their suitability when it comes to charging batteries of any kind – including sophisticated AGM batteries.

Trending Searches

High Amperage

The higher the amperage of a battery charger, the faster it charges your car battery. Most battery charger owners have made the switch to battery tender chargers because of the speed with which their batteries get filled up. Despite these exciting features, battery tender chargers are known to also do a good job in terms of maintaining car batteries when required.

Easy To Use

Battery tender chargers are normally designed with a hook feature to aid in keeping it in place when charging your car battery. 

To be fair, other battery chargers can be used to get the best result for your car batteries, but there’s something about the battery tender franchise that makes them an easy favorite. 

Is It Okay To Leave A Battery Tender On All The Time?

According to the battery tender manufacturing group, not only can you leave your battery tender on all the time, you can even leave it connected to your battery for as long as you like. Battery tender chargers are known to float current when the battery becomes full.

However, it’s only ideal that you check on your car battery every now and then to avoid any sort of eventuality – even if you leave them on for maintenance.

Likely, your battery might not be strong enough to withstand charging, and such defects can only be noticed when a charger is connected. 

Some persons are quick to blame their chargers for battery failure when in reality the battery itself is to be blamed. When a smart battery charger is connected to a battery, there’s very little chance of something going wrong — I mean, as low as 0.1%.

Everything created will last for a certain amount of time — nothing lasts forever. Regardless, products must be designed to last for a very long time, and that’s why battery tender chargers are designed with a 10-year warranty period, which is definitely the highest you will find in the market.

While there’s nothing wrong with leaving your battery tender on for a long amount of time, you should also apply common sense where necessary. (Read Also:How Long Do Jeep Cherokee Batteries Last?)

What Is The Difference Between A Battery Charger And A Battery Maintainer?

There have been lots of confusion regarding a battery charger and a battery maintainer, but before I go ahead to shed more light on this topic, I must explain them individually.

Battery Chargers

Just as the name implies, a battery charger is used to charge a battery using a current from the wall socket or a battery bank.

The working principle of a battery charger simply involves converting the power from an electric source into a pulse that helps to charge the battery. 

The pulse created helps to break off the sulfur formed on the plates and return them to the battery — this process helps to restore the battery. With battery chargers, you can specifically set the amount of amperage that controls the pulse allowed into your battery.(Read Also:Can A Bad Alternator Ruin The Battery?)

It has been generally advised to charge at a slower rate, and not at a faster rate to help prevent heat from building up which can damage the battery. Knowing the kind of battery you have will also determine the kind of charger you buy — not all battery chargers are ideal for all car batteries.

Battery Maintainer

In reality, most of the smart chargers in the market today are also designed as battery maintainers, albeit, battery maintainers have a different working principle compared to battery chargers.

Battery maintainers are more about making a battery usable for the long term, especially in cars or vehicles that are rarely used.

A battery maintainer can tell how much charge a battery has, after which, it proceeds to administer the required amount of charge necessary, and then goes off as soon as the charge is completed. Just like I stated earlier, the modern-day smart chargers are designed as battery maintainers as well.

So What’s The Difference?

The major difference between a battery charger and a battery maintainer is in their purpose. A battery charger is used for batteries that are required for everyday usage, while a battery maintainer is used for batteries that aren’t used frequently.

Battery maintainers can be left on a battery for a very long time without it harming the battery, while a battery charger shouldn’t be left too long on a battery — especially if it isn’t a smart charger. 

In summary, use a battery charger for batteries that are used frequently, and use a battery maintainer for batteries that are seldom used — it’s that simple. 

Can You Charge The Car Battery Without Disconnecting Terminals? 

Disconnecting the terminals of your battery is not necessary to charge it, just ensure you connect the positive wire first and ensure the battery charger is connected properly before proceeding. 

A lot of things can go wrong while charging your car batteries, and that’s why it’s important to follow these safety procedures below before proceeding. 

  • Ensure you check the battery for any sign of crack or corrosion. Such damage leaks can cause a possibility of acid leakage.(Read Also:How Long Can You Leave A Battery Tender On A Motorcycle?)
  • Do not attempt recharging a battery that’s already dried out. Dried-up batteries will require some amount of distilled water above the plates of the battery before they can be safe to recharge. 
  • Your battery terminals should be cleaned, as well as the cables. Your connection can only be as efficient as your apparatus, and cleaning them is the right step to take. 
  • Ensure you are using the right battery charger for your battery. Not all battery chargers are suitable for your battery, and you would only worsen the situation if you use a battery charger that isn’t compatible with your battery. 
  • When charging your car batteries, ensure you use a safe location and employ the use of emergency brakes to properly secure the car in a spot — you wouldn’t want your car rolling on its own while charging. 
  • Most importantly, confirm if the battery needs to be recharged. Most people are fond of attributing their car not starting to dead batteries, but that’s not always the case. You can start by checking the wires connecting the car and the batteries, and ensure they are in order. 

How To Charge A Car Battery

As soon as you determine that your car battery needs to be recharged, the following steps below will help you through the process. 

Step 1

Ensure your battery charger is compatible with your car battery

There is a chance that your battery charger might not be designed to charge your car batteries — don’t take it. Do a proper check by reading the instructions on the battery charger manual.

Know the make of your battery. Car batteries can be categorized into lead-acid batteries, lithium batteries, and SLI (starting, lighting, and ignition) batteries.

Knowing your battery spec should be the first thing you do before setting out to even buy your battery charger. 

Step 2

Wear your safety gears

You would definitely want to close all risk loopholes, and the best way to go about such is wearing the right safety wears which includes safety goggles and hand gloves.

Don’t leave yourself exposed to the hazards that might occur in the process of charging your car battery — prevention is always better than cure. 

Step 3

Disconnect the cables to gain access to the battery

To access the terminals, you would have to disconnect the cables that link the battery to your car. Start out by disconnecting the negative cable from the pole that carries the minus sign.

Endeavor to disconnect the negative cable before the positive cable to avoid any form of short circuit. 

Some batteries will require the use of a wrench to loosen the cable, so take note before proceeding. 

Step 4

Clean The Connections

If you observe some dirt or corrosion on the cables, it will do you good to remove them — using a wire brush, baking soda, and water will do justice. Try as much as you can to avoid touching the terminals with your bare hands. 

Step 5

Take out the battery if the charger cables are short

While there is nothing wrong with charging your car battery in the car, you might want to remove it if the charging cables are short. However, feel free to leave it in place if the cables are long enough. 

Step 5

Connect Your Battery Charger

Once you have carried out all the required steps outlined above, connect the battery charger to the battery. It’s better to place the battery charger on a stable surface so that it doesn’t fall off. 

Never be tempted to place the battery charger on the battery. Connect the positive terminal to the positive outlet of the battery, and do the same for the negative as well. A battery tender charger or any smart battery charger will know if you mix up the connection and won’t charge as a result. 

Step 6

Calibrate The Battery Charger

Based on your battery specification, you might want to manually input the charging mode or voltage required for a successful charge. However, a battery tender charger and other smart battery chargers will readily determine the setting required for your battery once connected. 

Step 7

Monitor The Charging Process

Unless you are carrying out maintenance charging, it’s important to always keep an eye out for the charging progress at intervals. A battery tender charger makes it easy by having Wi-Fi connected to your phone via an app to give you the precise reading on the level of your battery. It also goes into maintenance mode once the charging is completed. 

After Your Battery Is Full

Once your battery becomes full, disconnect the negative point of the charger from the negative pole before doing the same for the positive. After this, connect the positive car cable to the positive terminal, and do the same for the negative — your car should be up and running after this procedure.


When Should I Use A Battery Tender? 

Battery tender chargers are one of the best maintainer chargers you will find on the market. If you have a vehicle or battery you don’t use very often, you must use a battery tender charger to keep it active for the duration you won’t be using it.

Apart from maintaining your car batteries, battery tender chargers are good battery chargers as well, and they go into maintenance mode upon completion of charge. 

How Long Should You Drive To Charge A Car Battery? 

The general consensus says 30 min should be enough to give a meaningful charge on your battery. It might not be sufficient to fully charge your battery, but it should be enough to get you going. 

Can A  Battery Tender Ruin Your Car Battery? 

No, it won’t. Charging your battery is the best way to keep it alive, and not charging your car battery when necessary is the fastest way to ruin your car battery. 

Can You Start A Car With A Battery Tender Connected – Conclusion

In use, or not in use, your battery has to stay charged at all times, so it’s essential to get them ready for when you need them. Kindly stop your suggestions and questions in the comment section let’s talk.


Leave a Reply