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When you drive every day, your vehicle’s battery stays at a constant state of charge. When you don’t, and especially if a vehicle lives outside, the battery gradually drains. Nothing kills a car battery quicker than when a car sits for weeks and months on end, and battery drain is exacerbated by today’s computer-laden vehicles. Even when your ignition’s off, many high-tech computers in today’s vehicles continue to monitor onboard systems, including security, system software, and vehicle apps. These are just several reasons why a battery charger can be your best friend. Energy Storage System
So, what’s available? While some consumers will choose a high-power charger for fast charging a dead or weak battery; for most, a trickle charger/maintainer may be the best choice to maintain a battery’s charge over long periods of time.
Traditional trickle chargers apply low-amperage at a steady rate. They only provide a constant current to the battery, which requires a car owner to monitor the charger and the vehicle. They’ve evolved to smart, microprocessor-controlled battery charger-maintainers that turn on and off to avoid overcharging. Plug one in and forget it for a day, a week or the entire season.
These chargers/maintainers can also detect weak batteries and automatically cut power if the user improperly connects battery cables. Where there was once a simple green light to let you know a battery was charged, now there are multiple sensors and functions, plus LED monitors. Modern trickle chargers can also “desulfate” your battery, in essence cleaning it to reduce harmful sulfate crystals that accumulate in batteries as a natural part of battery operation.
The most affordable modern chargers can cost as little as $30 and some cost more than $100. There are also six-volt (used in some classic cars) and 12-volt units (used in all modern cars), depending on your needs. Read on to learn about five of the best options on the market today. Looking For Car Accessories? Match your car to your style with varied car accessories like seat covers, floor mats and more. Get competitive pricing from top brands here. Advertisement THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary. Explore Options On Amazon
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The three-amp Deltran Battery Tender can charge a battery and then switch to “float,” or maintenance mode. The four-step charging process helps prevent overcharging. While the Deltran Battery Tender cannot bring a fully discharged battery back to life; adaptive circuitry will keep a constant charge and automatically adjust the current for days, weeks, or months on end. Multiple LEDs indicate charging in progress, battery level, and when the unit is in float mode. There is a quick-disconnect harness to switch between the included ring terminals and alligator clips.
The Schumacher SC1281 ticks all of the boxes. It’s a 6/12-volt battery charger that offers 100-amp dead battery starting power, 30-amp weak battery boosting power, and 6/2 amp battery maintaining power. On-board advanced diagnostics include a battery and alternator tester that helps diagnose electrical problems. Advanced charging algorithms maximize battery charging, health and overall lifespan.
In addition to its jump-starting and trickle-charging capabilities, this product can automatically repair sulfated plates and when the battery is fully charged, it can run a rest cycle and cooldown, which also helps with battery longevity. Having such a combination product is a great idea as an emergency option to keep in your trunk. This product is heavier than most, but for all its additional functions, it’s worth the weight.
The Noco Genius functions more like a home EV charger than a regular battery maintainer. It mounts on a wall, comes in a waterproof enclosure, and can regulate the voltage based on the ambient temperature. The 2×2 features two pairs of clamps rated at 2 amps each (or 4 amps when using only one pair) and has five charging modes for varying battery types.
A “force mode” can charge dead batteries below 1 volt, and while charging, the Genius will detect and automatically repair older batteries that have been damaged by lead sulfate (see the FAQ). For vehicles that sit for months, the clamps feature detachable flat terminal clips for longer-term installation. Noco, a Cleveland-based company, has been in the battery business for more than 100 years.
Black+ Decker Battery Charger/Maintainer
If you want a no-frills battery trickle charger that gets the job done, the Black+Decker BM3B is the ticket. It’s lightweight (1.25 pounds), charges six-and 12-volt batteries, and can connect with O-ring terminals or battery clip connectors. Once a battery is fully charged, this unit automatically goes into float mode, which is a simple prevention for overcharging. It’s small, and durable with high Amazon ratings.
The inexpensive NEXPEAK 10-Amp charger is fast, powerful, durable and smart. The detailed digital display provides helpful status updates, battery temperature and more. This product has a cold mode and hot mode, as well as multi-stage charging.
Best For Fast-Charging and Cold Climates
Best For Fast-Charging and Cold Climates
Cold weather is one of the biggest causes of dead batteries. Even if the battery is not completely dead, cold temperatures can reduce battery charge to the point where it doesn’t have enough power to start your vehicle. The CTEK MUS 4.3 POLAR is designed specifically for colder climates and utilizes a water-and dust-resistant design that can stand up to the elements.
The CTEK offers specific modes for cold-weather charging as well as warm-weather mode that prevents overcharging. It weighs just two pounds and can bring a dead battery back to life in about 12 hours. It also provides automatic battery diagnosis and is protected against reverse polarity.
Traditional battery trickle chargers can only supply a constant charge. Modern battery maintainers will cycle on and off to avoid overcharging. Most will charge and then maintain 6-and 12-volt car batteries. We considered charger-maintainers that trickle-charge a battery to full charge and then maintain the battery charge indefinitely (for weeks or months) without damage. They’re more advanced and affordable.
We reviewed products based their rated current, informative front panels, protection against accidentally crossing cables and manufacturer reputation. We also looked at special features including the ability to jump-start a car with a dead battery and cold weather performance.
We evaluated all battery chargers based on these weighted metrics:
While a battery charger can feed power to a depleted battery, a maintainer keeps an already-charged battery from discharging. It monitors the state of the battery and prevents overcharging. This is different from a traditional trickle charger, which provides constant charging that can lead to overcharging.
There are two methods for connecting a charger-maintainer. The easiest is the use of “alligator” clips, so named because of the “teeth” on the clamps. The downside is that these clamps can pop off if not securely connected. The other method is the O-ring connector. The hook around the terminals and sit flush to the battery. You can leave them connected and some have mid-wire connection points so that you can leave them wired-in and disconnect the rest of the cable when you want to drive.
On a traditional battery charger or trickle charger, no. On a charger-maintainer like the products evaluated here, you can leave it on a stored car indefinitely. It charges until full, tapers off and restarts if the state of charge drops. If the power goes out, it resumes charging when power returns.
Higher prices (up to $125-$150) translate to longer cables, faster charge rates, the ability to “repair” an older battery (not always) and more information on the display. Some can jump-start a car that has a dead battery.
Yes. They can maintain a charged or nearly charged battery perfectly well. But fully charging a low battery could take several days. Some also don’t have the power to recharge a completely dead battery.
It’s the charge-maintaining mode after a car battery reaches full charge, which is about 13.5 volts for a 12-volt car battery. Float mode prevents overcharging and enhances battery life.
George Kennedy has reviewed cars and provided car advice for outlets such as Consumer Reports, CarGurus, U.S. News & World Report, the Boston Globe, AutoBlog and others. He is the managing editor for UpShift, the official publication of the Larz Anderson Auto Museum in Brookline, Massachusetts. George has owned multiple future-classics before they were collectible, including a 1986 Toyota 4Runner, an XJ Jeep Cherokee and a two-door Chevy Tahoe.
4000 Watt Inverter Brian Armstead has been involved in print, radio and television for over 46 years. He is president emeritus of the Washington Automotive Press Association, a North American Car, Truck and Utility of the Year (NACTOY) juror and is a regular contributor to several automotive media broadcasts and websites. In his spare time, Brian enjoys tending to the care and feeding of his Volvo, Mercedes-Benz and Land Rover vehicles.