BLACK+DECKER Battery Charger and Maintainer

Last updated date: November 23, 2019

DWYM Score

8.6

BLACK+DECKER Battery Charger and Maintainer

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We looked at the top Car Battery Chargers and dug through the reviews from some of the most popular review sites. Through this analysis, we've determined the best Car Battery Charger you should buy.

Editor's Note October 1, 2020:
Checkout The Best Car Battery Charger for a detailed review of all the top car battery chargers.

Overall Take


In our analysis of 156 expert reviews, the BLACK+DECKER BLACK+DECKER Battery Charger and Maintainer placed 9th when we looked at the top 13 products in the category. For the full ranking, see below.

From The Manufacturer

The BLACK+DECKER BM3B high frequency battery charger and maintainer is used to keep batteries in stored vehicles and battery applications at optimal capacity during the off season. Charges 6 volt and 12 volt AGM, GEL and WET batteries in RVs, specialty vehicles, antique and classic cars, marine deep cycle batteries, motorcycles, lawn mowers, ATVs, snowmobiles, and personal watercrafts. Slide the voltage selector switch to either 6V or 12V depending upon the battery you are charging. Connect the battery charger and maintainer with the included battery clips or battery ring terminals. Charging automatically stops when battery is fully charged or topped off and switches to float mode monitoring to maintain charge. Built-in circuit protection guards against overcharging, reverse polarity, or short circuit and is ETL certified for performance and safety. The BLACK+DECKER BM3B battery charger and maintainer has a built-in mounting bracket for convenient placement and includes a limited 1 year manufacturer warranty.

Expert Reviews

Expert Summarized Score

9.0
18 expert reviews

User Summarized Score

7.8
3,932 user reviews

What experts liked

It stays relatively cool throughout
- Best Selected Products
Versatile across engine types and connection preferences
- Battery Focus
It features a high frequency smart charging technology to keep the battery at an optimal charge.
- Top Portal Review
August 11, 2019 | Full review
The smart charging technology of the BM3B model ensure the battery remains at optimal charge. It will automatically switch between full charging and float mode, which is fairly impressive for a cheap unit.
- Pro Car Reviews
Built-in circuit protection protects your battery from overcharging, reverse polarity or short circuit.
- Best of Machinery
October 2, 2019 | Full review
Featuring a built-in circuit protection system, it guarantees the safety of the battery from reverse polarity, short circuit or overcharging.
- Easy Get Product
The battery clip helps to connect your battery for charging or maintaining, O-ring helps you charge your battery for an extended period, and DC plug charges your battery from the inside of your vehicle without touching.
- Disneysmmoms
September 9, 2019 | Full review
It has a durable and sturdy build and with its protection seal you can easily use it under all kinds of weather and temperature conditions
- Battery Chargers Expert
Keep the battery always at the optimum charge with smart technology
- A Guide Product
The body of the charger has special mounting holes, so securing the device in the needed position is a piece of cake
- Best Advisor
This Black and Decker battery charger features high frequency smart technology that ensures that your battery is kept at the optimal charge, even you don't know what that is. It also automatically switches charging modes to ensure that there is no over charging
- Drivr Zone
The charger is cheap, and the charger is tiny, so you can store it in your glove box or your garage. The charger is using a smart charging monitoring to charge your car battery the best way.
- Mechanic Base
June 7, 2020 | Full review
Protects from overcharging, short-circuiting, and reverse polarity
- Auto Quarterly
Its automated system also checks the battery’s capacity and stop charging when it is topped off or fully charged. Once the charging stops, it automatically switches to float mode monitoring to prevent overcharging, which often damages car and marine batteries.
- Ama Top 10
The Black & Decker BM3B can be alternated between 12V and 6V as per you batteries requirements, making it suitable for both small and large vehicles having either 12V or 6V.
- Car Battery Help
It comes with a smart charging technology that enables you to charge the battery without the fear of overcharge. The charger intelligently knows about the optimal charge, and it keeps the battery at that optimal charge during charging.
- Car Diagnosing
Reverse Polarity: It makes sure you face no loss if you end up connecting the battery in the wrong manner thanks to reverse polarity protection. So that, the unit will not work until you correct the connection, protecting you and the battery.
- OBD Advisor
September 7, 2019 | Full review
The clips, terminal rings, and DC plug have a quick connect attachments for convenient removal and attachment.
- Curate View
October 10, 2019 | Full review

What experts didn't like

The only downside of this model that we could see is that it does take a while to charge. If the battery is completely drained, you may need to charge it for ten hours or more.
- Battery Focus
The charger does not support AGM batteries and PWC batteries which is one of the limitations and shall be improved
- Battery Chargers Expert
It is quite expensive compared to other models
- A Guide Product
The clips do not always provide a tight grip on battery posts
- Best Advisor
Might be bulkier than others
- Drivr Zone
The charger has the capacity of 1.5 Ampere, which is not a lot but might be enough if you want to maintain charge of your car battery.
- Mechanic Base
June 7, 2020 | Full review
Poor quality LED lights
- Auto Quarterly
a few customers have reported that it can at times overcharge the battery.
- Car Battery Help
Connecting wires could be small
- Car Diagnosing
The cigarette lighter feature may not work for all cars.
- OBD Advisor
September 7, 2019 | Full review
The quality of build is not sturdy as the other prominent models.
- Curate View
October 10, 2019 | Full review

Our Expert Consultant

Vicki Liston 
Home Improvement Expert

Vicki Liston writes, produces, and narrates “On The Fly…DIY,” an award-winning home improvement and DIY show of unique project tutorials for the casual DIY’er.

Home improvement and all things DIY have been Liston’s passion since she bought her first house in 2007 and she started making video blogs in 2014. She’s performed hundreds of DIY projects, from small ones to major, wall-smashing renovations and can teach you how to make a trendy DIY barn door for cheap. The proceeds earned from “On The Fly…DIY” are donated to no-kill animal shelters and rescue organizations. You can find her show on Prime Video.

An Overview On Car Battery Chargers

A car battery charger is one of those things you might not think about buying until you need it, but then you will wish you had the foresight to purchase one in advance. Choosing the right vehicle battery jumper or charger device depends on several factors unique to your situation.

The primary consideration to determine is what type of car battery charger will best suit your needs.

Vicki Liston is the writer, producer and narrator of “On The Fly…DIY,” an award-winning home improvement and DIY show of unique project tutorials for the casual DIY’er.

“There are two basic types of car battery chargers: trickle and smart (also called multi-step) chargers,” shares Liston. “I don’t consider the float chargers to be actual ‘chargers,’ as they won’t resurrect a dead battery and are only used to maintain the charge.”

Learning the pros, cons and capabilities of a car battery charger type is helpful in the decision-making process.

“Trickle chargers are the most inexpensive,” Liston says, “but they are also the slowest.”

While this might seem like a downfall, it can be an advantage in certain situations.

“If you aren’t in a major rush to recharge, a trickle unit will serve you well,” explains Liston. “It’s actually better for the battery to charge slower than faster as a fast charge can generate a lot of heat and damage the battery.”

If safety is top of mind, a smart charger might be a better choice.

“Smart or multi-step chargers employ the use of a microprocessor to assess the battery and make automatic decisions about how to charge. The standard versions have the automatic stop feature to avoid overcharging, damage, and explosions,” Liston points out. “They can also detect if you’ve accidentally connected the cables to the wrong terminals, called ‘reverse polarity protection.’ A trickle charger will ruin a battery if connected incorrectly while a smart charger just won’t begin to charge at all. Understandably, these are the more expensive option, but they are also the safest.”

Be sure to check the amp rating on a potential car battery charger, as this will let you know how quickly it will charge your battery.

“Trickle chargers are rated at below one amp so it may take a few days to fully charge a battery,”  Liston says. “Again, slower is better for the battery, but you might not have the luxury of waiting around that long and need it up and running in a hurry.

“Higher rated chargers can run around 20 amps and the emergency ‘get this thing started NOW’ type chargers can crank out 40 amps to get you on the road in a hot minute,” continues Liston. “Some smart chargers allow you to choose a recharge setting based on your circumstances. You can set it lower when you have the time to wait and it won’t expend unnecessary, damaging heat. Set it higher only when the occasion calls for speed. You’ll have the best of both worlds in one charger.”

The Car Battery Charger Buying Guide

  • If you decide on a trickle car battery charger, Liston highly recommends an advanced model to ensure the safest operation possible. “The lower end models should not be ‘attached and forgotten’ as they will not stop charging when the battery has reached maximum capacity,” advises Liston. “Because of this, they run the risk of overcharging and even causing an explosion. The higher-end models, usually referred to as advanced trickle chargers, can detect when a battery is fully charged and either stop or automatically switch over to ‘float’ mode to maintain the charge. “
  • Since you should always put safety first, the right clamps are essential. “Whether you go with a trickle or a smart charger, I highly recommend looking for a model with spark-proof clamps,” Liston notes. “Sparks can not only damage both the charger and the battery but they can cause fires so this safety feature should be a must.”
  • “If you are only looking to keep a car battery charged, opt for a 12-volt only model,” suggests Liston. “However, if you’ve got other types of battery-operated vehicles, such as an ATV, boat, jet ski, riding lawn mower, or golf cart, you might want to consider a 6/12 or a 12/24 volt charger. This will allow you to use your charger in multiple applications instead of having a different charger for each volt size. 6/12/24 chargers are commercially available however they are extremely expensive and it’s cheaper to own both a 6/12 and a 12/24 than one 6/12/24 version.”