Tested: Deltran Battery Tender Junior 12V Charger and Maintainer

Chances are good your car starts up every time on the first try. Starts that last are something modern car owners don’t even think about most of the time. But for decades, you might take a deep breath or pray to your preferred deity before turning the key. Sometimes it would crank on the first try, other times it requires multiple attempts, and sometimes, it wouldn’t turn over at all. 

For classic car owners, these are all-too-familiar scenarios. That’s why battery maintainers (or “trickle chargers”) have become so ubiquitous within the hobby. Got an old car? Hook it up to the trickle charger and it takes the worry out of your next weekend cruise. The Deltran Battery Tender Junior 12V Charger and Maintainer is overly simple because of its almost singular purpose—ensure your classic starts up the next time you turn the key.

The Battery Tender Junior is a straightforward and easy-to-use battery charger and maintainer. It can be plugged into any wall outlet and is designed to charge most types of batteries. It has four modes or objectives; Initialization, Bulk Charge, Absorption, and Flat mode. Initialization checks the battery level, Bulk Charge brings the battery up to a constant current, and Absorption reduces the rate of charge until the battery is topped off. Once the battery is fully charged the product goes into Flat mode, which keeps the battery fully charged while preventing overcharging. 

We installed the Battery Tender Junior on a 1987 Mercedes-Benz 560SL. Mercedes-Benz vehicles from the 1980s are some of the most overengineered, well-built cars of all time, but that doesn’t mean you should skimp on maintaining them. The 560SL features a 5.6-liter V8 engine and its battery is located on the passenger side of the trunk behind some carpeting.

This product is designed for maintaining cars and personal watercraft (jet skis, etc). It can also be used to charge then maintain ATVs, motorcycles, lawnmowers, scooters, etc. Basically anything with a smaller battery. The Battery Tender Junior includes several features that will protect vehicles and their owners, including a spark-proof design and reverse-polarity protection.

Here’s a detailed breakdown of how this product scores in our evaluations:

Is the Battery Tender Jr a Good Value?

This product is a terrific value. At the time of this writing, it’s listed on Amazon for $39.95, down from $44.95. That’s a 12% price reduction. This product is also available for Prime same-day delivery. Even at full price, this is one of the more affordable trickle chargers on the market.

How easy is it to install?

The Battery Tender Junior is about as straightforward a trickle charger as you can get. Out of the box, you simply plug it into the wall, then connect the leads to the battery. There are two sets of leads, including temporary clamps and more long-term hoop harnesses. The harnesses will have the strongest and best connection, but the clamps are also good if you have unusual battery leads or prefer to quickly unclamp the charger before setting out on your ride. 

Alternatively, you can leave the hoop harnesses connected to one vehicle, unplug them from the battery tender’s power box, and attach the clamps to charge a second car or battery. It won’t be charging Car 1, but it will leave it ready for when you are done charging Car 2 with the quick clamps.

How can you tell when your battery is charged?

There is a simple red-green light on the front of the charger’s box. Solid red means it’s charging. Flashing green means the battery is more than 80% charged. Solid green means the battery is fully charged. Flashing red means the battery is not charging for some reason.

Are there any downsides to the Battery Tender Jr?

This is not a portable product. And it is not a jump-starter. If your car battery is dead, this is not an instant solution. And if you take it on the road, you’ll have to find a power outlet when you park. This is for maintaining a battery for a vehicle that is stored and might sit for some time.

Our Verdict: 

The trickle charger is meant to be an easy set-and-forget product, and the Battery Tender Jr executes that mission perfectly. It doesn’t have the instantaneous power to jump-start a dead battery and it’s not portable. It’s simple and straightforward battery maintenance. If you have an older vehicle that you don’t drive every day, the Battery Tender Jr ensures that you don’t have to think about your car in between drives.

Methodology

Traditional battery trickle chargers can only supply a constant charge. The modern maintainers will turn on and off to avoid overcharging. Most will charge and then maintain six- 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 don’t cost more than charger-only devices. We reviewed products at 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 evaluate all battery chargers based on these weighted metrics:

• Price (25%)
• Manufacturer Reputation (15%)
• Rate to charge (15%)
• Extra Feature (inverter, USB plugs, desulfator) (10%)
• Safety features (10%)
• Information display (5%)
• Jump starting/cold climates(5%)
• Storage/size/carrying ease (5%)
• Warranty/Return Policy (5%)
• Installation Materials (5%)