Best Buy recently recalled 5,100 MacBook Pro batteries after receiving reports that 14 MacBooks caught fire. That means MacBook Pro users who continue to use the failed batteries have roughly a 3 in 1,000 chance of having their laptop battery catch fire, possibly resulting in severe burns or a building fire causing thousands of dollars of damage. For comparison, U.S. residents have only a 1 in 10,000 chance of dying in an automobile accident even though driving seem much more dangerous than using a laptop.
If this were just MacBook Pro batteries, all of us PC users could just shrug it off and go about our lives while the MacBook Pro users quietly (and quickly) traded in their batteries for safer replacements. But this isn’t the first major battery recall—and it isn’t even the largest. On August 14, 2006, Dell recalled over 4.1 million batteries for 10 different models of their D-series laptop because their batteries were catching on fire and sometimes exploding. HP recalled 286,600 batteries; Lenovo recalled 205,000 world-wide; and the U.S. Consumer Product Safety Commission lists 58 other laptop battery recalls.
What’s going on here? If you’re like me, you spend practically all day (and and embarrassing percentage of the night) with a laptop in your lap or on your desk, so the thought your trusted digital friend catching fire and burning down your house is quite disturbing—and maybe a bit unbelievable. I didn’t believe it myself at first: I’ve been using laptops since 1993 and not one of them has caught fire or exploded, nor has anyone I know had a laptop catch fire. But then just because I’ve never had a heart attack doesn’t mean I don’t believe in them. (Side note: users of the recalled MacBook Pros are 75% more likely to have their MacBook burst into flames than they are to have a heart attack, although I imagine the former could cause the later.)
What Went Wrong: Why Does My Battery Explode?
All modern laptops, mobile phones, and tablets use lithium-ion batteries. Most other digital devices with built-in batteries use them too.
I’ll be frank with you, I never took high school physics or chemistry, so I have no clue what it means when Wikipedia says “lithium ions move from the anode to the cathode during discharge and back when charging.” I don’t know how lithium-ion batteries work, but I do have an idea of how they fail.
All batteries, regardless of type, convert electrical energy into some other form of energy. For example, the lead-acid batteries in typical cars convert electrical energy into chemical energy. When your device tries to draw energy out of them, they convert this other type of energy back into electrical energy, but moving electricity around regular wires generates waste heat and (in the wrong circumstances) this creates problems.
Although I skipped physics, I did take an electrical class, and it taught me about short circuits. Electricity usually travels in a circuit from its source to its destination and then back to its source. A short circuit occurs when electricity finds a way to get back to its source faster than intended, which usually means it doesn’t lose as much energy along the way as was intended. That extra energy has to go somewhere, and it usually becomes heat. Short circuits are well-known for creating fires.
When a battery short-circuits, it creates that extra heat just like my electronics teacher taught me. But lithium-ion batteries have two characteristics which make them especially dangerous:
- Lithium-ion batteries are partially made up of material which burns at a very high temperature. It burns so hot that it can be dangerous to even look at a lithium-ion battery fire because it could damage your eyesight.
- Lithium-ion battery cells are under pressure, so when the cell wall breaks, the internal material explodes outward.
Watch The PcPitStop Video Recreating a Battery Explosion
In 2006 PcPitStop helped expose these problems with lithium batteries and now in 2013 they have concluded that nothing has changed.
The Proximate Cause Of Battery Fires And Explosions
If short circuits cause lithium-ion fires and explosions, what causes the short circuits? In the Dell recall of 4.1 million batteries, the short circuit most commonly occurred when the battery case was crushed or penetrated.
Because that batch of batteries (produced by Sony) had poor quality control, the case contained little pieces of metal. As you know, metal conducts electricity, so when some of this metal was pushed into the electrical circuit, it created a short circuit, heated up, and caused the fire or explosion.
But that was only the Dell recall of Sony batteries. The more recent Apple MacBook Pro recall and other recent recalls are for batteries which seem to spontaneously catch fire. (None of the recent recalls I saw included exploding batteries, thankfully.) In these fires, the culprit seems to be the switches in the laptop and the battery which are designed to prevent overcharging.
If you unplug your powered-on laptop for 10 or 20 minutes to let the battery run down a little and then reconnect it to let it charge up again, you’ll probably notice that the battery gets hot. If you have a contact or infrared thermometer and want to do a little test, you can see that the closer the battery gets to fully charged, the hotter it gets.
(If you have an app for your computer which tells you what percent charged your battery is, you may also note that the closer your battery gets to fully-charged, the longer it takes to add each additional percentage point to the total charged amount.)
Why does it get hotter? The closer the battery gets to fully charged, the less it wants to accept more electrical energy, so it rejects some of this power by turning it into waste heat.
Now, all working laptops have a circuit in them which turns off power from the charger when the battery reaches fully charged. Batteries are also supposed to have a fail-safe circuit which disables incoming electricity when they get too hot or something tries to overcharge the battery.
In the case of the defective MacBook Pro batteries, the fail-safe circuit in the battery was defective, so it didn’t do its job. Although I don’t have all the details, I suspect those poorly-made batteries were also reporting their voltage status to the MacBook Pro incorrectly, so the MacBook Pro continued to try to charge the batteries past fully charged. That meant the battery was creating more and more waste heat, which eventually lead to the fire.
Signs Your Laptop May Soon Explode
Now that you know what’s going on, you can take intelligent steps to protect yourself. Since the previous battery fires and explosions had two different causes, there are two different obvious symptoms to watch out for:
- Impact damage.
- Hot batteries.
For impact damage, remember that your battery will probably not explode or catch fire immediately. A short circuit will take several seconds or minutes to get hot enough to breach the case of the lithium-ion battery. In some cases, the impact damage will create a short circuit which only activates under certain circumstances (such as slight overcharging); in these cases, each time the short circuit briefly occurs, it may melt a tiny bit more of your lithium-ion case until it creates as full-blown short circuit which results in fire or explosion—but this can be days, weeks, or months after you drop your battery.
For hot batteries, it’s important to pay attention to any computer which seems to be hot. If your laptop is uncomfortably hot on your lap, your first step should be to search the web for information about your model of laptop—for example, do other people with your laptop report it being uncomfortably hot? In my case, reviews of my ThinkPad R500 say it’s surprisingly cool even under heavy load, so if I sensed it getting hot, I’d immediately worry that something was wrong.
Immediate Response To Heat, Smoke, And Flames
The following advice is what I would do, but I’m not a fire marshall, so please seek professional assistance if you need it.
If you sense your laptop getting unexpectedly hot, there may still be time to save the laptop (although you should have the battery tested before you continue using it). Here is what you need to do.
- Do NOT disconnect the charger immediately. This may be your first instinct, but if the battery is short circuiting, the charger’s grounding may be the only thing saving you from being electrocuted. (This is unlikely, but why take chances?)
- If possible, put the laptop on a reasonably non-flammable surface. The floor is a good place even if it’s carpeted—many carpets in the U.S. include fire-retardant material or treatment.
- Hold the power button down until your laptop turns off. Yes, I know you will lose your unsaved documents and Windows or Mac will complain about a sudden shutdown, but you want your laptop to stop drawing power from the battery as quick as possible to try and break the short circuit.
- Step away from your laptop, grab the charger wire, and yank it out of your laptop. Yes, I also know that you’re not supposed to disconnect electrical devices by yanking out the cord this way (because you might break the cord) but you don’t want to be holding your laptop when you break its ground connection in case the short circuit will electrocute you.
- If your laptop starts doing something weird (sparking, smoking, making noises even though it’s turned off—or anything else which isn’t right) don’t go near it. It’s not just a fire hazard now, it’s also an electrical hazard. If it seems to be all right, now is your chance to stop reacting and start thinking. It’s also a good time to clear the room of pets and children, and to enlist other adults into helping you.
- From across the room, throw a few drops of tap water (not purified water) on to your laptop. Tap water contains a little bit of metal, so it conducts electricity. If the water droplets which land on your laptop spark or fizz, stay away from the laptop and call the fire department immediately. If the droplets just sit there, you probably don’t have a short circuit, so you can very carefully approach your laptop and gently pick it up. If the battery stays hot, even though the laptop is off, throw the laptop outside (I’m serious) and call the fire department.
- If the laptop seems fine, disconnect the battery, put it in the least-inflammable box you have (a fire-proof safe works great) and store it outside and away from inflammable objects until you have a chance to take it to a computer repair shop or electrician for diagnosis. If the battery is found faulty, you can get a free replacement from the manufacturer as a thank you for not suing them.
Smoke And Flames: Take Immediate Action
If your laptop starts to spew smoke or catches on fire, you only have seconds to respond. Once again, you don’t want to remove the charging cord while you’re still touching the laptop to avoid possible electrocution. But you also don’t want to leave the laptop inside a structure where it can set the whole building on fire.
That means you need to make a quick judgment call: are you more afraid of being electrocuted or more afraid of your house or office catching fire? If you’re afraid of electrocution, follow the same steps and the instructions above, but call the fire department immediately and don’t approach your laptop until they arrive.
If you want to save your building from fire and are willing to risk potential electrocution, unplug your laptop from the wall and get it outside as quick as possible. Try to keep the battery part of the laptop as far away from your body as possible and don’t look at it more than necessary in case it explodes.
If the laptop is already on fire, I recommend that you consider flinging it through a window—even if that window is closed. A broken window is cheaper to repair than a burnt-down home or office.
What about your fire extinguisher? Even if you’re lucky to have an extinguisher in the same room as your computer, it may not be the right type. Lithium-ion battery fires are partially metal fires which require expensive Class-D fire extinguishers rather than the much more common A/B/C extinguishers (A/B/C/E in Europe and Australia).
However, sodium chloride—table salt—and sodium bicarbonate (baking soda) are reasonably effective at fighting metal and electrical fires, so a decent home solution to a burning battery is to stand as far away as possible and dump as much salt and baking soda on it as you have available.
Don’t use an A/B/C fire extinguisher until the metal fire is completely put out, whether by the salt and baking soda or simply by letting it burn itself out. Metal fires burn so hot that when the A/B/C fire extinguisher material hits them, they can explode and fling super-heated metal fragments into you and the rest of the room, burning you and starting more fires.
Even more important is to not throw water on the fire. Any water besides distilled water will conduct electricity, possibly electrocuting you or setting other parts of the room on fire.
For the most part, we’re dependent on laptop manufacturers to keep us safe. There are no affordable replacements for lithium-ion batteries which deliver similar results, so we’re stuck with them for now.
As more and more problems build up, consumer protection groups and regulatory bodies are more likely to advocate for stricter manufacturing requirements. And manufactures themselves, to avoid expensive lawsuits, are likely to voluntarily perform more quality assurance.
But that’s all in the future. (And it’s all hypothetical.) What can you do now to protect yourself?
- Check the U.S. Consumer Product Safety Commission website for your model of laptop or digital device to see if there is a recall order. If there is a recall, don’t delay—get your free replacement battery immediately.
- If possible, don’t leave your laptop plugged in unattended. When you leave home to go to work, hibernate your laptop and unplug it. It only takes 30 seconds (or faster with an SSD drive) to unhibernate your laptop when you get home.
- Remove the battery from laptops which never move. If you keep your laptop on your desk at work 24/7 and it’s always plugged in, you don’t need your battery, so just remove it. As long as your laptop is plugged in, the battery is not required to operate it, and removing the battery eliminates the risk of lithium-ion battery fires.
- Pay attention. In most cases, you may have several minutes between the time your laptop battery starts getting unreasonably hot and when the fire starts. If you take quick action, you may be able to entirely avoid damage to your laptop, your home, and your body.