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Summary
  • Battery maintainers charge your battery through a series of small charges over long periods of time. They act as smart trickle chargers, each using an internal control system that prevents overcharging.
  • The best time to use a battery maintainer is when you foresee yourself not starting the vehicle for an extended amount of time. Battery maintainers are great for storing your vehicle.
  • Battery maintainers differ from battery chargers because chargers use higher voltages to charge batteries quickly when you’re trying to get your dead battery up and running right away.
  • Make sure to consider your battery’s chemistry, voltage, and amperage when buying a battery maintainer or charger.

Your vehicle’s battery is an important part of its ignition and electrical systems. When you turn your ignition, your battery provides a jolt of power to crank the starter and ignite the fuel in the engine via the spark plugs. This allows the vehicle to start, and from there, the battery works with the alternator to power your vehicle’s different electrical components. The alternator also keeps the battery charged, but it only works when the vehicle is running. You can see how this can become a problem if your vehicle sits unused for an extended amount of time. Your battery will lose its charge and you’ll be unable to start your vehicle. That’s where battery maintainers come in.

What Is a Battery Maintainer?

Battery maintainers are handy little devices that can charge your battery through a series of small charges over long periods of time. There are solar-powered battery maintainers and those that plug into your wall. They allow your battery to sit idle for ages while staying topped up.

Essentially, battery maintainers are smart trickle chargers. They can read when your battery is fully charged and stop charging to prevent overcharging. Battery maintainers are even called trickle chargers in some places, but not all trickle chargers have the smart charging feature of true battery maintainers.

How Does a Battery Maintainer Work?

Battery maintainers use an internal control system, which is in charge of monitoring your battery’s voltage so it can stop charging once your battery is full. It also activates the trickle charge function once the battery’s charge falls below a certain threshold. Battery maintainers keep up charge rate, also known as a float charge or trickle charge, that’s typically at or under two amperes (amps). Certain models offer a pulse mode as well, which shoots high-intensity electrical pulses through the plates to break down any sulfation buildup.

The battery maintainer is connected to your battery through a set of clamps. The red (positive) clamp connects to the positive terminal on the battery while the black (negative) clamp connects to the negative terminal. Make sure to attach these clamps to the battery before plugging in the maintainer.

When To Use a Battery Maintainer

The best time to use a battery maintainer is when you foresee yourself not starting the vehicle for an extended amount of time. For instance, a battery maintainer is perfect if you plan on storing your vehicle. It won’t overcharge your battery but it will keep it topped up. Starting your vehicle after its long stint in storage with a battery maintainer is much easier than if you’d simply left the battery to discharge. Overall, the main draw of using a battery maintainer is the fact that it won’t overcharge your battery.

Now, how long can you leave a battery maintainer on? As long as the maintainer is still working and the battery doesn’t break down, you can theoretically keep your maintainer connected to and topping up your battery’s charge indefinitely.

Differences Between Battery Maintainers vs. Chargers

As handy as battery maintainers are, they aren’t always the tool for the job. Battery maintainers and battery chargers might seem interchangeable at first glance, but they have different uses despite their similarities.

Battery chargers send a constant charge to the battery, and most regular battery chargers use high voltages to charge the battery faster than battery maintainers. Battery chargers aren’t usually able to detect when the battery is full unless they come with an automatic shutoff feature. As a result, they can overcharge your battery if left connected for extended periods of time. This can easily damage the battery.

Battery chargers are best used when you’re trying to get your dead battery up and running right away, like if you left your lights on overnight and you don’t want to ask another person to help you jumpstart your vehicle. They’re also helpful if you didn’t use a battery maintainer when you first stored your vehicle and the battery’s discharged over the time it’s been unused.

In the end, use a battery maintainer for storage and a battery charger for more immediate battery charging.

What Batteries Can You Use Battery Maintainers With?

If you’re looking to use a battery maintainer for your vehicle, rest assured that they work with both 6- and 12-volt batteries. You just need to buy a maintainer that runs at the same voltage. The type of battery you have will also affect what type of battery maintainer you need, but standard and absorbent glass mat (AGM) batteries can both work with a maintainer. Do your research on your battery type before buying a maintainer.

Battery Maintainer and Charger Features To Consider

There are a few things you should keep in mind when buying a battery maintainer or charger:

Compatibility With Battery Chemistry

As we’ve mentioned, battery maintainers and chargers need to work with the type of battery you have. Make sure you buy an AGM battery maintainer for your AGM battery and a standard battery maintainer for your standard battery. The same goes for chargers. If you attempt to charge with an incompatible maintainer or charger, it could damage your battery.

Voltage

Make sure to match the voltage of your battery maintainer or charger to your battery’s output voltage. Most modern vehicles run on 12-volt batteries, but older ones might use 6-volt batteries. Whichever it is, purchase a battery maintainer or charger that matches.

Amperage

Finally, there’s amperage. This really only matters for chargers because maintainers use lower amperage to trickle charge your battery. Find your battery’s amp-hour (Ah) rating on its label or the manufacturer’s website and make sure the charger is a minimum of 10% of your battery’s Ah rating. For example, a 50Ah car battery will need a 5-amp charger. In theory, you can use higher-amp chargers, but they might damage your battery over time.

Now that you know all about what battery maintainers are and what to look for when buying one, it’s time to decide whether you need one. If you plan to store your vehicle for a while, we say why not? Best to buy and use a battery maintainer now so you don’t worry about charging and jump-starting your vehicle months later.

About The Author
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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