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.

Been using this in my Harley Davidson for 5 years and it’s still working perfectly! Never have had a bad battery!

This is a fantastic projectI tested it with meter and when flashing it is charging at 14.4v.When float charge solid green light it sits at 13.6Works great!Hook to battery plug it in and leave it alone.Check battery water often if flooded!

Two quotes from the manual that may surprise you:1. "If the battery to be maintained has fallen below 2 volts, the battery cannot be recharged with this unit"So if the battery is totally dead, you're out of luck here. Not a problem for me ;-)2. "Charge above freezing temperature and below 40 degree Celsius (C) (104 degree Fahrenheit)"That's a problem for me. I have a seldom used car in my detached, unheated garage. In winter here it essentially never gets above freezing, and we typically have a few stretches of days where it never gets above 0F.I'm using this maintainer anyway, so far with great success: just plugged the adapter into the car's cigarette lighter, then plugged the maintainer's power cord into a wall outlet. Works great! I'm not a bona fide battery expert, but I'm not worried about it because a lead-acid battery (which my car has) can be charged at temperatures above -20C (-4F). My guess (and it's just a guess) is that they say "above freezing" because that's necessary for *some* kinds of batteries, and the manual is long-winded enough already. Next time it falls below 0F here I'll disconnect the device for the duration, but between 0F and 32F (freezing) I'll leave it attached. This is not a recommendation, just telling you what I decided. If something bad happens as a result, I'll update this review (provided I survive ;-) ).One other point: when I first attached the device, the green LED came on solid. But that's supposed to mean the battery is fully charged - and I knew it wasn't. Searching online I found a slightly different edition of the BM3B manual, which explained that when the device is first connected correctly the solid green LED may persist for up to 2 minutes (longer the more drained the battery), while the maintainer figured out the likely state of the battery. Indeed, I just left it alone, and after about a minute the green LED started to blink (meaning the maintainer is charging the battery).The green LED continued to blink for more than a day, which wasn't surprising: the car's battery was quite low, and charging in cold weather goes slower than in pleasant weather. For a week since then, the green LED has been on solid, and the car starts up very easily. Just opening the trunk (which activates a small light) is enough to put the device into charging mode again, and when the trunk is closed the green LED stops blinking again after just a few seconds.So I'm very happy with this so far - deducting a star just because the manual isn't clear enough on the points above.

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.