BLACK+DECKER J312B Jump Starter: 600 Peak/300 Instant Amps

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Product Specifications

300 instant starting amp and 600 peak amps
Internal charging cube for use with household extension cord
12-Volt outlet
Reverse polarity alarm
Light and compact for easy transport and storage

Product Description

Size:600 Peak Amp The BLACK+DECKER 300-amp portable jump starter is ideal for jump starting most all v6 engines in cars and light duty trucks. Featuring a visual and audible reverse polarity alarm to warn against improper connection to the battery terminals. The unit has a built in ac charger, that will operate with most all household extension cords. This portable jump starter is also a source of portable power with a 12-volt, and high output USB outlets, it can charge many small electronic devices.

Product Reviews

Not a bad little unit, but be aware of its limits!

I purchased this unit from Home Depot rather than Amazon, but I wish I had known Amazon carried it - it’s cheaper here!Anyway, I just wanted to speak to a few things that people have mentioned in their reviews. Some asked about the amp-hour rating of the battery, others criticized it for not holding a charge for a long period of time, still others apparently were unhappy that it didn’t fulfill their expectations after they tried to use it without following the manufacturer’s instructions!Okay, what is the amp-hour rating? Don’t worry about it - for jump-starting. Amp-hour ratings are essentially meaningless for this purpose. What is more important for jump-starting is the peak ampere output. This unit is rated at 900 amps peak, so it should be adequate for jumping almost everything but those vehicles with large V-8 gas or diesel engines, and, with proper technique, it may even suffice for those!So what is “proper technique”? Well, you have to keep some basic electrical facts in mind. When you turn he ignition key to the “Start” position and the starter first energizes, it draws a LOT of current, typically about 300 to 400 amps for “average” cars, and more for larger ones. (Small cars with smaller engines will draw somewhat less.) The relatively small battery in this unit is designed to deliver surprisingly high power for its size, but there are limits imposed by the internal construction of the battery, and the size of the various connections within the power pack itself.So, you try to start your car, and discover you left the headlights on last night. You grab your handy-dandy little jump-starter and connect it the way the instructions say to: e.g., red clamp to the positive terminal of the battery, and the black clamp to an unpainted metal part of the engine. You get in the car and note, with some satisfaction, that the dome light now comes on. (It didn’t before!) You turn the key to the “On” position and watch as the dash comes to life, with all the lights and such. Also, the radio begins to play - good! Now, you turn the key to “Start.” The dash goes nearly dead, and you hear a sort of “grunt” from the starter - but no start. Only the dreaded “click-click-click” noise from the starter solenoid that means, “No way, buddy!” @#*#+#^@#!!!So what did you do wrong? Well, let’s see. You have a completely depleted large lead-acid battery in your car. When you connected the jump-starter, the dead battery began to draw a considerable amount of power from the (much smaller!) battery in the power pack, probably something on the order of 200 amps or so, if not more. Then, you turned on the key. All the various systems in the car start to draw power from the battery as well, maybe another 20 to perhaps as much as 100 amps, depending on the car. If you sit there gazing at all the pretty lights and listening to the radio, it will draw that much more power, and that energy is lost forever. Finally when you try to start the car, the power pack has depleted too much of its energy, and simply doesn’t have enough left to crank your engine.So what’s the solution? Easy! Just do this: connect the power pack to the dead battery - then go away for a couple of minutes! Don’t get in the car; just wait patiently for a while. Why? Because you are giving the power pack time to transfer as much energy as it can to your car’s main battery. The main battery is designed to deliver large amounts of energy in short bursts. Then, when you go back outside and get in your car, don’t fiddle around. Close the door, make sure the radio and heater/AC are turned off, and then turn the key in one smooth motion from “Off” all the way to the “Start” position. The engine should crank and start normally (assuming it starts normally all the time: if you have a junker, all bets are off!)Okay, so that problem’s solved. Now, back to amp-hours. Where does that become a useful number? Well, it’s only good for comparing performance for similar types of batteries being used in fairly low-current usage, such as powering a light (or two, or three…), or maybe even a TV when using an inverter. I’m not going to go into too much detail here; I’ll just describe a fairly typical situation.Let’s say you are out camping, and you have a nice little lamp your wife thought was “just darling” for camping. It has a 60 watt incandescent bulb in it, and it lights up your camp site quite nicely, thank you very much. Along with that, you have a 20” flat-screen TV plugged in so you won’t have to miss a single episode of “Big Bang Theory.” Unfortunately, just as Penny is about to give in (again!) to Leonard’s wimpy nerd charm, the power pack gives a distorted whine, and the TV and lamp go out! What? It’s been on for less than an hour! What’s going on here?Well, let’s see. Using some basic electricity formulas, we can calculate about how long it should last. The battery in my unit says it’s rated at 17 amp-hours. (Hmm. It looks awfully small for that rating, but okay…) Now, the lamp is 65 watts. The TV? Uh - let me see… it pulls… let’s see… 85 watts.b So - total draw is about 1.5 amps, or 150 watts. One thing we don’t know is the efficiency rating of the built-in inverter on the power pack. We can make a pretty good “educated guess”, though.(A quick word about inverters. Their efficiency may vary from something just over 50% when a trickle of power is being used, to something over 90% when the output is approaching the inverters rated output. An inverter will use some power from your batteries even when you are not drawing any AC power from it. This results in low efficiencies at low power levels.)Since the inverter in this unit is rated at 500 watts, and you’ve been drawing only 150 watts, let’s say it’s been operating at…oh, let’s be generous and say about 70% efficiency. (Close enough for government work…) That means it’s been drawing 195 watts from the battery, or 16.25 amps! Yeah, it’s gonna be sucked down in somewhat less than an hour… because the inverter will shut down when the voltage drops below about 11 or so.If you want to use it for lights, I would recommend you use CFL lamps, or, better still, LEDs. They draw a lot less current. And - forget that TV: it just draws too much. Use your DVR at home to record Big Bang Theory, and watch it when you get back.Also, don’t complain about it not holding a charge when you tried to use it and it was dead after it had been sitting on the shelf for six months! Lead-acid batteries will self-discharge over a fairly short time, and the instructions for these things tell you to recharge them about once a month to keep the battery fully charged. Lead-acid batteries are not happy being discharged to less than 60% of their rated capacity; they will lose their ability to fully recharge if left discharged for very long. Keep it charged up, and it’ll last a long time.Finally, the initial charge for these batteries takes about 40 hours. When you get a new unit, the battery has an initial charge on it from the manufacturing process. The plates in the battery have to be charged for the full 40-hour period to “condition” them, otherwise, it will never - ever! - be able to gain full capacity, and, in all probability, not last very long. So, when you first open the box, plug in the charger and connect it to the battery, and let it sit there for a couple of days. Don’t pay any attention to the green light: it’ll probably come on after anywhere from 12 to 24 hours. Just leave it plugged in for at least the full 40 hours, and it’ll be good. Oh, and - don’t leave it plugged in too long, either. The battery will overcharge, and that will damage it, too.I bought mine knowing all this stuff beforehand, so I would say, yes, it does what it’s supposed to do. I’m happy with mine; I think you’ll be happy with it, too, if you are careful to make sure it meets your needs before you shell out your hard-earned money.

Beware. Does not hold charge.

Awful. Worked one time and hasn’t held a charge since. Contacted Black & Decker customer support for some guidance and have yet to receive a response. What a disappointment and expected a much better product from Black & Decker.

Great little backup power device, good car starter, kind of cheap compressor.

This thing’s a gem.I have a relative that needs CPAP, but lives where power can go out overnight fairly often. The battery in this runs her CPAP all night long without issue. If the power goes out she just gets it from her car and the CPAP can run all night.The compressor is cheap and slow, but would work in an emergency.The car starter works as advertised.But the inverter is pretty quiet and very effective. She keeps the power at full by using a male to male cigarette lighter extension cord. That way she has an emergency roadside assistance kit (which she can use to power the CPAP if she sleeps in the car while her husband drives.)If you don’t know what CPAP is, it’s a device to help people breathe at night. It treats sleep apnea - a disease that can kill you. A recent study of over 670000 people showed sleep apnea patients are more likely to die in 5 years than the general public. 25% more likely to die. If you wake up tired, snore a lot, or have been seen to stop breathing as you sleep - get it checked!I hit upon using this device for backup power after I saw that the medical supply companies wanted over $450 for a battery pack for her CPAP. They wanted $89 just for a DC converter that plugs into your car’s cigarette lighter. I accomplished $539 of medical device power capacity with this one little $89 black and decker power solution. Only one problem: Not sure you can carry THIS on an airplane.Update eight months and going strong no issues whatsoever have used it to start vehicles five times now using a 12 V male to male cord keeps it topped up at all times I never have to plug it into an AC outlet .The airlines told me I cannot carry it on an airplane though so I created an alternative that is allowed out of 18 650 batteries I purchased here on Amazon . I wish the inverter in this unit could be taken out and used with my in-flight solution I’ve gone through two inverters already and I’m going to have to pony up for a pure sine wave inverter. Even though I have plenty of volts and amps nothing seems to power her CPAP as flawlessly as this little Black & Decker does. ( Since all CPAP devices are not created equally I will give you her model it is a Resmed eight which could be powered without an inverter on 12 V DC but Rez med switch the polarity on their unit so that is opposite of what you would expect if you choose to use straight DC to power your CPAP be aware that these companies want to sell you their proprietary DC power cord and they’re not afraid to let you burn your machine up if you don’t)

NO GOOD

This did not hold a charge. The light indicators say full when it is not fully charged. Even after several recharges it would not last long.

Excellent BUT read the directions before using. It will last a very long time.

Keeps on ticking! I used this to light up my golf cart for a parade. It seems to have plenty of power and exceeded my expectations. FULLY CHARGE BEFORE FIRST USE I charged mine for 48 hours first. Now I plug it in once per month to keep it in good shape.

Seems to do the job.

I needed to replace the jump pack I carry on my boat as my old Vector (10 y/o) wouldn’t hold a charge for more than a couple of days. I did some research on a replacement unit, but bought a Shumacher at Walmart. When I got it home, the cables were so short, it was unusable and I returned it. On a pop-up ad (which I normally hate), this unit was displayed. After reading the reviews, I ordered unit on Fri July 4th and received on Tues the 8th. It was about ³⁄₄ charged and needed only 3 hours to get the green fully charged light. Have not needed on boat yet, but used on a couple of other jumps for lawn equipment. So far, so good.

holds it’s charge great. Have used it tailgating many times at 49er …

No issues, holds it’s charge great. Have used it tailgating many times at 49er games to plug and play the music. After the last tailgate charged it up full and put it away in the garage. 8 months later pushed the button on the unit that checks the charge and it was still at “high”. A good item to buy that can give you some peace of mind…can jump your battery, air up your tire, or provide a lot of power during an outage if needed.

very nice.. works well

very nice ..works well

Not longer holds a charge. Zero customer service from …

Not longer holds a charge. Zero customer service from B+D… they claim they don’t manufacture it and tell you to call some random company who could not care less than their…

I got a lemon, you might too. Amazon will not exchange on behalf of B&Ds 1 year manufacture warranty

I used it once camping, worked fine, recharged it when I got home and then put it in storage. tried using it about 60-70 days later and it won’t hold a charge.

waste of money

It doesn’t work. i was out of town for a month and missed the return window. I definitely regret buying it. waste of money.

JUNK

This product is garbage. It was fully charged and on 2 occasions I tried to jump my car. It failed both times. I’ve had it a year and it won’t even hold a charge.

Aside from this the unit has worked great on powering small lights and small

Unit indicates that you can connect up to 500 watts using the 120v ac plug. Connected a fan (300 watt) and the unit burned up some internal wires, smoke came shooting out.

Role after a

Role after a week

I was very happy to find this

I had a similar B+D unit for years but it finally died. I was very happy to find this. I will use it for maintaining correct tire pressure and backup if electricity goes off.

So nice, I bought it twice

This is the second time I have purchased this set. The last one I had lasted seven years. Technically, the original is still working w/the exception of the DC -> AC…