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Even if the question may go into the technical details of a laptop computer specifications, I would like to know general experience of travellers concerning that topic.

Some airlines offer power sockets at their seats where it is possible to plug a computer. So far, I have not been able to know limitations of the supplied power, such as maximum power output.

In my current case, I have an Acer Predator Helios 300 as my main laptop. It is a gaming-grade machine, meaning it should suck a little more power than the average MacBook. I do not find a clear power rating indication in watts, and intelligent power management of nowadays should modulate the actual power drawn according to the current usage. Let's say that typing documents requires less power than playing a top-tier 3D game.

Each time I plug it in, the green light on the airplane socket goes off. It means that the breaker has tripped, likely because I am trying to draw too much power. Surprisingly, it also happens when I plug the charger alone without the laptop at the other end. This was my experience so far on Delta and United.

I usually ride trains quite a lot in Europe. Rail cars are equipped with sockets nowadays and my laptop was powered by them without issues in all situations. In France, for instance, the train sockets are labeled 100 watts max, therefore my laptop should be drawing less. So, why is is a problem when done in airplanes?

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    Your adapter requires 180W. Maybe those airplanes don’t provide 180 Watts? – Hanky Panky Aug 15 at 14:40
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    Most trains get a nice big power supply rated in MW, and they can quite easily divert quite a lot of current to the user accessible sockets. Consider than even a double unit duplex TGV with over 1000 seats would only represent 100 kW if everybody was drawing 100 W, while the engines draw up to 10 MW. A plane is a very different beast, and generating power is costly. There’s already a lot of vital systems to power, and the IFE, so there’s much less margin. Also, for security reasons, breakers are probably a lot more sensitive. – jcaron Aug 15 at 15:50
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    "meaning it should suck a little more power than the average MacBook." A little more? A Macbook draws maybe 50 W, so your computer draws almost four times that. – d-b Aug 16 at 2:12
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    If you really insist on charging your laptop while traveling, perhaps you could replace the charger with a lighter one and configure your laptop for lower power usage by for instance disabling the separate graphics card and using the integrated chip, and using Intel's Extreme Tuning Utility to lower overall power usage by the CPU and other components. That said, you should be very aware of what you're doing so the laptop doesn't attempt to draw more power than needed. – Sebastiaan van den Broek Aug 16 at 3:37
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    If you trip a 100 W fuse by connecting a PSU without the laptop connected, something is wrong with the PSU. 180 W rating on the PSU doesn't mean it needs to draw 180 W, it (typically) means that it can provide up to 180 W output. – Zulan Aug 16 at 11:29

12 Answers 12

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Overcurrent isn't the only reason for an airline circuit to trip. It might also be looking for ground faults/residual current (GFCI/RCD) or listening for arc faults (AFCI). Any appliance can have either problem.

Trains are electric beasts - even a diesel train has the diesel engine driving a giant electric generator on the order of 3 million watts (with electric, a lot more; with no hard upper limit since it is part of mains distribution and can cheerfully surge 10x or more). This electricity is divvied up between electric drive motors and hotel loads (galley, HVAC, your laptop). Power distribution is just like to your house: transformers, commercial off-the-shelf (COTS) Siemens panelboards with normal trip curves (tolerant of surges) and receptacles handling mains 230V power. In fact, cleaners use it for their vacuum cleaners. The labeling is statutory: so the conductor can prohibit people from cooking or running heaters, and because the whole car must share 1 or 2 3680W circuits.

Whereas on an airline, power is at a high premium. A 737 has two 90,000 watt generators, which together couldn't even power an Amtrak dining car... This must power all the galley, lighting and avionics loads. Further, this power is not 120/230V mains; for that it must go through exotic converters, where wattage costs money, and surges are absolutely intolerable. Further, fire is the worst nightmare in aviation, and electrical fires are the #1 cause, so extraordinary circuit protection is installed and all this equipment must be aerospace grade not COTS like the train. So provisioning power to passengers is a big deal, and it is tightly controlled.

Your gaming laptop is custom enough that there hasn't been a huge amount of engineering to reduce things like inrush current, which is caused by lazy power supply design.

I agree that the laptop isn't pulling that much power if you're not crunching/gaming, so it may be possible. Your best bet is push back on your manufacturer to give you a better power block, or go onto the aftermarket and get one.

You can test it by sticking it on a Kill-a-Watt or logging ammeter and plugging the power supply in. The Kill-a-Watt will tell you power draw second by second, or the logging ammeter wil tell you about inrush-current spikes.

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    Comments are not for extended discussion; this conversation has been moved to chat. – Willeke♦ Aug 18 at 15:22
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If a socket says "100 W max", it doesn't mean, that your laptop would be drawing less. Your laptop/charger will draw what it needs. The socket will provide the power that your laptop needs, until it reaches the rating of the circuit breaker, and it will trip (as you have experienced). Also, as the 2 comments already have mentioned, a load peak can always happen if you plug the charger in, even if there is no laptop connected, or if you only type a document on your laptop.

If it doesn't happen in trains, than it just means that the circuit breakers have either a higher rating (even if it says less on the socket) or are not that sensitive to short load peaks as the ones on the planes.

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    Trains have a 16A breaker which supplies more than 1 socket, so one guy using his 1000Watt gaming machine is no problem, 4 people at once is. So no LAN parties on the track! – Christian Aug 16 at 7:13
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    @Christian but, a 24 hour train ride is the perfect opportunity for an OpenTTD megamap multiplayer megamarathon. How can the railway companies not see that? – John Dvorak Aug 16 at 7:18
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    @JohnDvorak Railway companies are very aware of that, they specifically request this to annoy their customers – Christian Aug 16 at 7:19
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    The main problem is fire and short cuts. So airlines are much more restrictive. Fire on train is much less a problem than a fire in a plane. In any case, the problem is not in your computer, but on your charger. buy one which allow much less watts. It will take you more time to charge, but you are in a plane: you much have time. – Giacomo Catenazzi Aug 16 at 8:36
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    @GiacomoCatenazzi: "Buy a more reasonable charger" should be an answer not a comment. :-) – R.. Aug 16 at 16:03
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This alone explains it all:

it also happens when I plug the charger alone without the laptop at the other end.

Because of the way power supplies are constructed, they draw extremely short, but very large "inrush" current. This can sometimes even visually manifest itself as a tiny spark when plugging it in. The PSU doesn't even need to be turned on, it's about charging it's input capacitors that always stay connected to mains.

It doesn't trip the breakers in your home or a train, because regular breakers work with a delay. It means you can draw much more than breaker rated current, as long as it's ultra-short. Simply, the grid is so big and inert that such spike isn't harmful. Unfortunately, plane's grid is neither big nor strong - so airplane makers install faster breakers that are successfully tripped by your big PSU.

What can you do about it? Find a PSU with smaller input caps. It's more of hit and miss without knowing their insides. Statistically, smaller (in terms of both power and physical dimensions) PSUs have smaller input caps.

Try getting other PSU that still works with your laptop. Possibly a smaller one - many laptops can work with smaller PSUs. It won't supply enough power for 100% load and charging the battery at the same time, but it can provide just enough power to extend battery life for few hours, hopefully to get you through the flight. Ask on the Electrical Engineering StackExchange how can you test the inrush current at home without even boarding the plane.

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    Why is this not the top answer? – Sentinel Aug 16 at 20:03
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    @Sentinel it mostly repeats the info of the top answer with less detail. Why do you think it should be top? – Tim Aug 17 at 0:06
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    @Tim Your comment proves that I have failed to explain the distinction between PSU rated power (which is meaningless) and inrush current (which is the culprit). How can I improve my answer? – Agent_L Aug 17 at 6:08
  • Seconded that this is the best answer. – R.. Aug 17 at 20:15
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    @Tim: FWIW "capacitor" is the modern term for that part. – Ben Voigt Aug 18 at 1:16
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I had a laptop that drew too much power for the socket. So I didn't plug it in and use it at the same time. I used it on battery, then when I wasn't using it (eg during meals) I closed the lid and plugged it in. This reduced the draw enough to keep the breaker from flipping. This may not make any and all laptops work with finicky power supplies on planes, but it increases your chances of success.

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    That sounds like good advice in general but it doesn't help the asker, since they say their power supply trips the breaker even if it's not attached to the laptop. – David Richerby Aug 15 at 23:03
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    The key point here is to avoid running the system and charging the battery at the same time, which practically divides the required maximum power in half. – Dmitry Grigoryev Aug 16 at 12:41
  • I've done the same, but have also had luck using it while plugged in if it was already charged to 100% (and didn't do anything taxing like playing games) – user2813274 Aug 16 at 12:46
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    @DmitryGrigoryev No, the key point is that even running the power supply when it's not connected to the laptop is enough to trip the breaker. At that point, it's neither running the system nor charging the battery. – David Richerby Aug 16 at 17:21
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Unfortunately there is no negotiation mechanism between a mains outlet and your laptop. So your laptop has no idea that it needs to limit its current draw.

I would not take the "100W max" label on the sockets on the train as meaning much. AFAICT sockets on planes typically have local protection (the green light that goes out), while sockets on trains are typically connected to shared circuits.

Possible workarounds may include

  • Turn the laptop off, so it only draws the current needed to charge the battery and doesn't try to run the laptop and charge the battery at the same time.
  • Use a smaller power brick, some laptop vendors have a mechanism for indicating how much power the brick can supply to the laptop, so using a smaller brick lets you limit the power. When I Google your laptop the accessories page links me to a 65W adapter that may work for this. If you are lucky enough to have a laptop that supports charging over USB C then that may be an option too.
  • Remove the battery, a laptop can't try to charge a battery that is not installed, on the downside if the power does trip out your laptop loses power immediately.
  • Try to start your trip with a fully charged battery.
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    The asker says that the power supply trips the breaker even if it's not attached to the laptop, so your first and third suggestions, while being good general advice, won't work in this case. – David Richerby Aug 15 at 23:05
  • My laptop runs on USB-C, but if I plug it to any PSU that cannot provide 20V, it just doesn't work. My old laptop could use a lower-rated brick, but drawing part of the power from the battery, and never increasing it at all, even without load (and would never boot connected to that brick). – Davidmh Aug 16 at 12:24
  • Actually there are mechanisms which let the laptop know what PSU is plugged into them. I don't have an Acer, but my HP laptop automatically deactivates battery charging while ON if the travel PSU is used. – Dmitry Grigoryev Aug 16 at 12:37
  • Or buy a travel laptop, and use that instead. These days, computers are inexpensive enough that a person can have more than one. – Jim MacKenzie Aug 16 at 16:20
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When you power your laptop on, you're likely drawing the peak 180W. That may be causing issues with not just the circuit breaker, but any surge suppression or arc-fault detectors as well. While this is for Virgin Atlantic circa 2010, I can't see them being too terribly different from other airlines flying planes today

Each pair of outlets at every row of three can support a maximum total of 225 watts per this certification, but there is "enough power" onboard for every outlet on average to deliver 82 watts to every outlet in the aircraft at any given time.

and

The issue we believe Mr. Rosen unfortunately encountered relates to usage/surge protection and can affect some laptop users, (per what the second post notes. Newer laptops and certain types of AC charger/adaptors in particular have been more closely linked to this occurrence. Seat guru, an airline blog has a good overview of this too here. Unfortunately some computer power supplies may present a request for power with a momentary amperage spike that is interpreted by the in-seat power system as a surge.

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    The asker says the breaker trips even if the charger isn't connected to the laptop. The issue is the charger's inrush current. – David Richerby Aug 16 at 17:23
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You can try finding a compatible charger that supplies fewer watts, say 60 or 80 watts.

The effect would be that your battery might discharge slowly while you use your computer (much slower than if you are not using any charger) and it recharges more slowly when the laptop gets turned off, but hopefully it gets you round the problem you have. If you do this, turn the screen brightness down as low as possible. Turn WiFi and Bluetooth off as well, assuming they are no use on an airplane anyway.

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  • Planes often have WiFi, these days. Especially long-haul. But even then, you probably don't need it on most of the time. – David Richerby Aug 15 at 23:10
  • If you're going to do this you should either start with a charged battery, or plug in several minutes before switching on, as it can fail to boot while charging – Chris H Aug 16 at 8:30
  • @Chris H my Dell refuses to boot with a lesser charger, even a legit Dell charger of same voltage but less power. Workaround is to unplug it, boot from battery, then plug it again. – Emilio M Bumachar Aug 16 at 10:29
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    @EmilioMBumachar That's typical Dell design. Unlike many manufacturers they have communications between the power supply and the laptop. My experience of laptops has been more forgiving (Asus/Lenovo/Acer and longer ago Toshiba and Compaq): Get the voltage about right, use the right connector, and it works. The desktop Dells I've used have had similarly mean aspects to the design. – Chris H Aug 16 at 10:37
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Surprisingly, [the green light on the airplane socket goes off] when I plug the charger alone without the laptop at the other end.

This means the actual power consumption has nothing to do with it, it's purely the inrush current phenomenon. Your laptop has a beefy capacitor near the input which is supposed to store enough energy for the laptop to stay powered while the AC voltage goes through the zero-crossing. The capacitor is big enough to produce the initial current high enough to trip the protection circuit on connection.

Power supplies rated for less power have smaller capacitors and thus less inrush current, so if you can find one that works with your laptop, it's worth a try. Capacitors also hold their charge for about half a minute, so if you have two sockets available, plugging the supply into one (tripping it), then immediately unplugging it and plugging to the second socket may help. In any case, airplane sockets are typically rated for 60W, so even if the protection doesn't trip at initial connection, it may trip later on when the laptop will start consuming power, so anything above 60W will be trial and error.

Even if you don't do anything intensive on the laptop, it will typically consume full power from the mains to charge the battery. Some laptops can be set up not to charge the battery when it's above 50..90%, which may help with a power supply rated for more than 60W.

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There is actually a technical solution, but you may not be able to apply it. I include it for completeness anyway.

Negative Temperature Coefficient resisitors are used to limit inrush current. However fitting one would mean customising mains-powered equipment, which you probably aren't qualified to do: either modifying the power supply or building a short extension lead with the NTC resistor in it. I'd probably do the latter, but I've had some training in designing mains-powered kit. In some jurisdictions it's probably even illegal, and strange-looking custom electronics don't tend to go down too well with aviation security.

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    The legality of connecting homebrew electrical equipment on a plane aside, there is no reason it needs to be less safe than a mass produced item. This is legit advise, why the downvotes? Matter of fact, not too long ago I was trying to find such a solution, but didn't exactly know what to look for. This answer would have been helpful. – Someone Aug 16 at 12:30
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    @DmitryGrigoryev I'm not going to say your concerns are unfounded, though I think they're easily dealt with by someone competent and I've warned about the need for competence. Thank you for stating your disagreement clearly; it helps people make up their minds. – Chris H Aug 16 at 14:28
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    I don't disagree with the content of this answer, but I don't think it belongs on this particular (Travel) site. If this question were asked on Electrical Engineering then I think it would be appropriate there. – Joe Aug 16 at 16:36
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    Is there any rule on StackExchange as to how safe a proposed solution has to be? I get what you are all saying, but unless such a rule exists, downvoting this only because it's from the "don't try this at home" category, would unnecessarily bury good information. – Someone Aug 16 at 17:44
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    @Ben I've often travelled with custom cables, both for personal use and on business (e.g. spare parts for equipment). They aren't forbidden, they just attract annoying attention if not professional quality (hence my final caveat including "strange-looking"). This isn't just Europe but transatlantic flights. If someone can do the job safely they can also do it tidily enough that it wouldn't look out of the ordinary. If they can't do either, they shouldn't try. I admit it's only appropriate for a minority – Chris H Aug 16 at 19:33
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I had this problem a few years ago with my MacbookPro. This was using a grounded Australian plug. Strangely, when I connected a European (or maybe it was US) plug adapter (not a transformer), it worked OK. My guess was either the Australian plugs were not making good contact, or it was some sort of ground protection kicking in, which the non-grounded international adapter did not have (which is a slight worry to be honest).

I did sometimes get a tickle from the aluminium cover of my older Mac laptops....

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  • That is probably arc-fault detection because of poor contact. That happens either with "everything sockets " which do every plug but none well, or if you force plugs where they do not go. – Harper - Reinstate Monica Aug 17 at 16:19
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From personal experience on many flights: it's probably an inrush current issue, but repeatedly unplugging and replugging often keeps the mysterious green light on. Plugging in with the lid closed, then opening the lid often helps.

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  • I came to post this answer myself, but don't have enough rep on this site. The outlets usually reset almost immediately on un-plugging, so quickly re-plugging a few times with the laptop disconnected from the power supply is my go-to solution to get it to work. – alex.forencich Aug 18 at 8:46
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You are most likely drawing more than 100 watts of power. According to Acer, the Predator Helios 300 comes with either a 135 watt or 180 watt power supply, depending on model. The airplane outlet is likely correct in detecting a current overdraw and shutting down. In my experience, the outlet limiters on planes are overzealous and will shut down draws as low as 80 watts, despite a listed 100 watt limit. The circuitry controlling outlets on trains may be more permissive, and allow your overdrawing device.

The solution is to use a lower-draw power supply for your laptop. Some laptops, such as Apple's MacBooks or Microsoft's Surface line, are designed to accept power supplies with varying capability. You can find small power adapters that will draw only 35 or 40 watts and are ideal for travel. Most laptops when idle or performing light tasks will draw fewer than 20 watts. If more power is required than the adapter can provide, for example while running 3D accelerated games, the laptop will draw from its battery to cover the energy gap. When the battery is exhausted, it may downclock or shut down.

Unfortunately, your Predator Helios laptop does not appear to have sophisticated power management circuitry to allow for the safe use of lower-wattage power supplies. Acer sells only one model of power supply per laptop. A recent post at the LinusTechTips forum describes a user's experience powering an Acer Predator G3-571 with a 90 watt supply, when a 180 watt supply is recommended. They report their machine switching from plug to battery power, depending on the workload. They also report symptoms of poor voltage stability from the power supply (flickering keyboard lights), likely as the laptop is drawing more current than the supply was designed to handle.

It's my opinion that this is unsafe for both the laptop, which may become unstable, and for the power supply, which could overheat and become damaged. I do not recommend trying this.

One final option is to shut down your laptop before connecting the power supply. When shut off, the power draw to charge the battery alone might be less than 100 watts. You may not be able to use your laptop while plugged in, but you might be able to get away with closing the lid and charging its battery.

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  • "One final option is to shut down your laptop before connecting the power supply" The question says the breaker trips even when the transformer alone, with no laptop attached, is plugged in. – Ben Voigt Aug 18 at 1:18
  • You could only have posted this when you did, by carelessly ignoring that the question clearly specifies the issue occurs with the laptop not connected to the charger. The actual issue of inrush current (which is not operational power consumption) was already well explained before you made this posting. – Chris Stratton Aug 18 at 17:29
  • Hi Chris, thanks for being rude for no particular reason. I didn't carelessly ignore this aspect the question. I read and understood it. Smaller wattage power supplies will have smaller smoothing capacitors and smaller inrush current. The advice towards the end of my answer is in the event that inrush doesn't trip the protection circuit. – Zack Schilling Aug 19 at 2:21

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