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What Is a Trickle Charger?

A low battery warning light in a car's instrument cluster.

Anytime a battery sits unused for a long period of time, it slowly loses its charge. It’s not likely to happen if you leave your car sitting for a few days, but leaving it for a few weeks or through the winter could be enough to drain the battery. Fortunately, there is a device that can help: the trickle charger.

But just what is a trickle charger, and why might you need one? Here we’ll explain.

What is a Trickle Charger?Battery Charger / Maintainer – 1.5A – 6/12 Volts – Automatic

A trickle charger slowly charges a battery to keep it topped off while it sits for an extended time. The idea is to provide a constant charge at a low voltage. There are also regular battery chargers, which charge the battery quickly, but these must be monitored and disconnected as soon as a full charge is reached so that they don’t overcharge the battery and cause damage.

You may also see something called a battery maintainer. There isn’t much of a difference between a trickle charger and a battery maintainer, but maintainers may come with features that automatically stop charging to save power if the device senses that the battery is full. Otherwise, both devices provide a constant, low-voltage charge and can be left connected to an unused battery for a long period of time. Think of maintainers and trickle chargers as low and slow, like good barbecue. A standard battery charger, on the other hand, is more like an untended grill that will turn burgers into charcoal if left unattended.

Trickle chargers and maintainers are great for keeping your seasonal or rarely-used vehicles, such as tractors or motorcycles, ready to run at a moment’s notice.

A Few Words on Safety

Make sure your vehicle is parked out of the rain in a well-ventilated location when you use a trickle charger. Charging can produce hydrogen gas, so a supply of fresh air is essential to avoid the chance of a fire or explosion. Ensure that the engine is off and the key is removed from the ignition before you connect the trickle charger (or any other battery accessory, like jumper cables, for that matter).

How to Use a Trickle Charger

A trickle charger will usually come as a simple box that houses a charger with a power cable and two alligator clips like those you’d see on a set of jumper cables. Set the charger’s voltage and amperage to match your vehicle’s and you’ll be ready to hook it up.

Connect the red/positive clip to the positive cable, and the black/negative to a ground location. Once these are securely attached, plug the unit into your wall outlet and turn it on. Don’t touch the wires once the device is on, as you could give yourself a shock.

Those are the basics of trickle chargers. Consider using one anytime you leave a car or other equipment with a battery sitting unused for long periods so it will be ready to go when you return.

Check out all the batteries and battery accessories available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information about how to charge your battery, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy Flickr.


Nicole Wakelin View All

Nicole Wakelin covers the automotive industry as a freelance journalist for a variety of outlets. Her work includes news pieces, podcasts, radio, written reviews, and video reviews. She can be found in The Boston Globe, CarGurus, BestRide, US News and World Report, and AAA along with lifestyle blogs like Be Car Chic, The Other PTA, and She Buys Cars. She is active on social media with a large following on both Twitter and Instagram and currently serves as Vice President of the New England Motor Press Association.

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