BLACK+DECKER BM3B Fully Automatic 6V/12V Battery Charger/Maintainer with Cable Clamps and O-Ring Terminals, Multi, 1.5 Amp

Somehow the world has made me come back to this product page a little over 8 years later and I figured I would write a quick review. TL;DR - Charger works well and has given me zero issues. Pros: The cord is plenty long for my garage outlet so I don't even need an extension cord when plugging in my "race car" as my kids call it. I only get to drive it once every few weeks so I throw this charger on there just to not worry about the battery possibly going dead. The power inverter is in the middle and can be mounted so you could possibly run power from an outlet, mount it on the wall or a workbench, and then have a good amount of cable to plug in a battery, depending on your application. It includes several ways to connect to the battery terminals. I just use the clamps and I have not had any issues. They are pretty sturdy and should hold up to normal use without issues. The unit has an easy to understand switch and lights for status. Switch to convert it from 6V to 12V, depending on what you are charging. The status light has simple icons that give a good indication of what the charger is doing. Cons: Not an issue for me but something you should be aware of with this (and likely most chargers of this type in this price range) charger is that it's not going to be super fast at charging a battery that is very low. Most of the time, that's not a big deal as its intended to maintain a battery that is sitting for long periods of time. Just don't assume you can plug this into a dead battery and come back an hour later and have it ready to go. Depending on how empty the battery is and how much power is needed to turn whatever you are powering over, it will likely take longer than that. Overall, well worth the 20 something bucks I spent on it. Not something I can always say with stuff from Amazon these days.

The recent purchase was a second unit having had many years of solid experiences with the first. It is ideal for longer periods of vehicle storage. It’s easy to use and priced right.

I finally charged the dead and drained battery of my car. It doesn’t charge the dead battery initially, and I read the instructions that it requires a minimum of 2 volts to charge it. So I thought I was out of luck because the battery was completely drained to jump start it. I left my car in storage and hadn’t run it for a while and the battery slowly drained completely. Out of desperation, and after reading the instructions for awhile, then I realized that because it has a polarity sensor to detect the correct positive vs negative poles, so I figured that the minimum of 2 volts in the battery is designed for the polarity sensor to charge it with the polarity in order to prevent shorting the battery if it charges with the opposite polarity at the dead state without any minimum voltage to ensure it’s the correct polarity. So then I decided to trick the charger to start charging the dead battery by giving the dead battery some minimum voltage by connecting the jumper cable to another car’s functioning battery, but not attempt to jump start it yet (because the other car’s battery doesn’t have enough amperage to jump start the completely drained battery). So after I connected the jumper cable to the dead battery to another car’s good battery with the correct polarity first. Then I connect the charger cable to the dead battery. Now the charger detected the minimum 2 volts (borrowed from the other good battery) with the correct polarity, and now the green LED light starts blinking. So it’s a good sign that the charger is beginning the charging process. Then I disconnect the jumper cable and let the charger continue charging without the jumper cable connected. So that did the trick to start charging a completely drained/dead battery by borrowing the minimum 2 volts from the other battery to trick and override the polarity sensor to turn on charging the drained battery from the dead state. It finally fully charged my dead battery after it trickle charged for about 24 hrs because it’s only charging at the rate 1 amp so I expect it to take that long to fully charge a dead battery. After that I can start my car on it’s own and it works fine after that. Now I keep the car battery continues to charge by the charger as maintenance rather than letting the battery to drain dead before charging it for a car that has not run for awhile. And I need the run the car once in a while to circulate the fluid and engine rather than letting it sit there for a month. So the charger can charge a dead battery if you know how to trick it to make it work.

Had bad experienced with NOCO always stuck on Standby, try out B&D and received 2 dead ones when plugged in power, no LED lit. Returned to Amazon, got 2 new ones. Let see how their quality control this time. Update: Got 2 new ones works fine, somewhat my fault and somewhat B&D poor design. LED will not turn on UNLESS battery cable is connected to car battery then connect to charger with power AC plugged in wall socket to complete the loop. If only AC power plugged into wall socket, LED is OFF which is poor design that made me think device is defective. It should have power/ready LED but this device only have CHARGING (Green) or FAULT (Red) LED. The first 2 charger I returned probably works fine but I'm used to plug in a device in AC wall socket, LED power/standby should turned on first. I got no LED light so thought it malfunction. So before you claim the product is defect due to NO LED LIGHT lit when plugged into wall AC, make sure connect the other end to your battery terminal to make complete loop in order for GREEN LED to flash (charging.) This is not a good friendly design but it works and fairly priced.

I am using it as a battery tender for my BMW R9T 2015, it has a setting for 6V or 12 V . I have it set on the 12 V and automatically looks at the voltage of the battery in the bike and starts to charge when it sees a low voltage. since I dont ride too often I like to have the battery charged when I want to go riding. If I left the bike without a tender I would be charging the battery and reprogramming some of the functions of the bike the night before I want to ride… With the charger I just have to disconnect and go for the ride… no worries. The previous tender lasted 5 years , lets see how long this one lasts… simple enough, plug on the walk, connect to my prewired set up and start charging if needed. If it does not need the charge it stays standby … plug and forget. It comes with two extra connectors, o e a clip on and the standard bolt on to the battery. The plug has a cover so that when it is not charging it can be stowed away. nice for the price. Update!!: 15 days after putting it to work on my Motorcycle battery it died. The other one I have has been in service for years this one is dead... No good , returning within the date they allow.

I plan on using this on a vehicle to maintain the battery when I will be away for weeks or longer. This B&D labelled unit specifies it switches to float mode when battery if fully charged. Also it is rated 1.5 amp, so I feel it will not damage my battery. I have not use it yet, but volt meter showed it was charging at 15 DCV, the correct lights on the unit were light, so I am confident it will keep my battery topped off when I am not using the vehicle. Compact size with nice long cords. *Note the unit does not come in a Black and Decker printed box, but a plain brown box that looks like it was made for the unit. Also the first unit I received was missing the alligator connector, and Amazon took the return and shipped my reorder immediately. Easy to use, and a good value.

First , I'am an electronic design engineer and have dealt with most types of batteries in my design projects. I also use and buy charging equipment fairly regularly. I have this 2013 ford Taurus which I recently found out has an above normal parasitic battery draw which is intermittent, but will bring a fully charged battery down to 12.2 volts in 2 days and discharge below starting voltage in 5 days of sitting. I always fix my own electrical problems, but the difficulty of tracking this down versus just plugging in a standy charger , forced my to decide on the charger option. So I get this B&D BM3B and it seems like it should work. But in my testing, I found that the charger would repeatedly charge to a voltage of 14.9 volts , then cycle down to 13.8. I reasoned that this was becatuse the phantom load of my car was discharging the battery enough to send the B&D into the absorption stage. Since I did not want the battery to be cycled , I decided to use a constant float charger for the car. Then I thought I would use it to maintain a pair of golf cart batteries over the winter. To test I put this charger on and monitor the current and voltage. Again after the the charger charged up to 14.9 volts , the current decreased until the voltage dropped to 13.8. I expected the charger to stay at 13.8 float voltage until the battery self discharge ( in a month or so ) dropped the voltage, but no , in a short period of time it just repeated the full charge cycle even though it was not needed. I'am shure that over the long run this behavior would be detrimental to the batteries. This charger would be ok for occasional use, but not to maintain batteries over an extended period.

Works great and a small size.

Good product

i used it for straight 4 months, than it broke cuz its 110v and we have only 220v here in Saudi.. but it stood this time! i believe if it was 220v compliant i wouldn’t need ever to change it

I am sufficiently impressed with the B&D battery maintainer that this is the second such unit I have purchased. I have five 12V car batteries for my seasonal vehicles and I check the batteries with my multimeter once every month during the off season. In order to assure that they all remain in good working condition, I have been using a Deltran Battery Tender 800 (worked well for two years until the float/maintenance voltage circuit failed and the unit started overcharging my batteries), a Motomaster Eliminator unit (never did work to my satisfaction and completely died after about a year) and the B&D unit, the first of which has been working beautifully for the past year. This most recent B&D addition to my maintainer inventory seems to be working every bit as well as I expected based on my previous experience. It pumps up my batteries to 13.3V, at which point the float/maintenance circuit switches to monitor mode. Given that this B&D battery maintainer is the least expensive of the three different manufacturers' units and has been performing as well as stated by the manufacturer, I feel justified in saying go for it. I consider this unit to be best of the three and, at the price listed on amazon.ca, a good investment.

How good are they, send a product to Australia with a US power plug on the product. How am meant to use the product? Very disappointed with the distributor.

Excelente produto