Airline power sockets shut down when I plug my computer in. How can I avoid that?

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.

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.

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.

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.

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.

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.

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.

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.

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.

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....

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.

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.