My brother gave me a dead gaming laptop (Asus GL503V). He bought it on eBay some time ago but it died a couple of months after. A couple of days ago he gave it to me, and I noticed that the charger was relatively small considering the size of the laptop. When I checked, the charger was 45W, while the laptop was 180W.

I saw the computer working in my brother's hands and the laptop would constantly start charging and stop charging every 20 seconds or so. He told me one day it just died out of nowhere.

When I connect the smaller charger, nothing lights up and nothing at all happens. Could the motherboard be dead or could it just need a new charger?

Here are the specs of the Onn Universal 45W Laptop Power Adapter Charger from Walmart that was used to replace the original Asus adapter:

ONA17HO024 adapter, 19.5V output, 2.31A, 45W

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    Buy the proper ac adapter, i doubt the laptop is damaged but the adapter is. – Moab Oct 22 '19 at 21:50
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    Yup. 180W / 45W = 4. The AC adapter died a toasty death 🔥 trying to provide 4x more power than it was ever designed to to a very power-hungry laptop. – Mr Ethernet Oct 22 '19 at 21:58
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    If the battery is toast because of old age the laptop will try to run essentially on the adapter which is too small to power it. – Peter - Reinstate Monica Oct 23 '19 at 14:32
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    @MrEthernet Is this based on actual EE knowledge or are you just making a guess here? I don't think that a properly designed power supply with current limiting would "die a toasty death" because it's only going to supply it's rated power regardless of how much the load is trying to draw. If you plug a phone capable of charging from 2A into a 500mA computer USB port the computer won't catch fire, it will just charge the phone 4 times slower. As far as I can tell the only problems that would arise from using a properly designed 45W charger would be slower charge times. – JShorthouse Oct 24 '19 at 11:56
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    @JShorthouse "...are you just making a guess here?" Do some research into the OP's replacement adapter. This isn't a "properly designed power supply with current limiting". It's a budget $20 charger from Walmart, with multiple customer complaints of overheating. walmart.com/ip/Onn-Universal-45W-Laptop-Power-Adapter-Charger/… – Mr Ethernet Oct 24 '19 at 12:00

An EE here. Your power supply is inadequate to power the laptop. Since this model has a non-removable battery, your best bet is to attempt powering it using a properly rated supply. Any other testing would be inconclusive.

A bit more details, if you want to understand how parts of the puzzle connect here. First of all, suppose the laptop is totally off, and you are trying to charge the battery alone. In this disassembly video at 3:07 the rating of the battery can be clearly seen:

ASUS B41N1411 battery pack

Model B41N1711, nominal voltage 15.2V, capacity (typical) 4240mAh.

A typical Li-ion battery charger (the battery is marked generic Li-ion, but judging by its thin rectangular cells, it's most likely a Li-polymer type; this is not really important) works in 3 different modes. To explain them, let's use C for the battery capacity divided by 1 hour: C=4.3A (rounding up to 2 digits). This parameter is important, as it is used as the maximum charging current for the battery.

The battery appears to contain 4 cells, ostensibly used in series, as the per-cell voltage of 15.2V/4=3.8V is in a typical range for a Li-ion cell. This is important, as we base the threshold on a per-cell voltage (and current through all 4 cells is the same, as they are connected in series. Actual picture is much more complex, but this is not essential for understanding, except why I am talking about voltages as small as 3V: that's a per-cell voltage).

When the battery is deeply discharged, the charging circuit supplies a constant current of 0.1×C, which is only 0.43A, something that your supply is perfectly capable of. This is the first mode. It is important to limit the charge current at this stage, because if you connect the cell to (an ideal) voltage source, it will consume tens of times more than C, and likely explode from overheating.

When the battery is conditioned enough so that per-cell voltage reaches ~3V, the charger is safe to switch to the full charge current mode (but still a constant current!), so that it switches to supplying the full C, which is 4.3A. Your supply is rated for only half of this current.

Now, for the sake of completeness, I should mention the third mode, the constant voltage charging. Normally, the charging circuit would switch to this mode when the per-cell voltage reaches some 0.3V above the rated voltage, which would be 3.8+0.3=4.1V per cell. The battery took enough charge so we know it wont gulp too much current and explode, and now we feed the cell voltage, and measure charging current. Note it was the other way round until now. When the current naturally drops to 0.1×C, the charging circuit is turned off, as the battery is now considered fully charged.

What happens if the charger is trying to feed 4.3A into the battery, but your supply is rated for 2.3A? This depends on how much self-protecting circuitry is there in the supply. A quality power supply will turn itself off for a time, and attempt to restart in a few seconds. A cheap supply will experience a voltage sag (well below its rated output), and more likely than not overheat and die, either quietly or letting its magic smoke out. Some supplies have as simple a thing inside as a sacrificial fuse which melts when the current draw is too high.

What I think happened in your case. The charging circuitry inside the laptop is usually much smarter than that in a cheap power supply, because an error there can result in an explosion, fire, injury, death and/or a huge class action settlement. When it switched from the 0.1C to C constant current mode, the supply either turned itself off (if it's smarter) or simply sagged (if not). In either case, the charger detected an anomaly and stopped charging the battery. After a short while, it attempted a restart. Again, it starts gently at 0.1C, measures the voltage (after a couple seconds, to let the chemistry settle), and, detecting the 3V threshold voltage, switches to full C current mode... rinse, repeat. You've got the on-off charge cycle, and the 20s cycle time does not look implausible, although it seems nearly too long a time.

The notebook does not always consume 180W! Imagine putting a 200W incandescent bulb into this case: it would be quite hot. The actual power consumption is much less, at least until you load both the CPU and GPU to full capacity and turn screen backlight to eleven, while simultaneously charging the battery at the maximum current--and still the rating is usually given with a large margin. So, when doing almost nothing, even a powered laptop would discharge the battery very gently while our cycle of overloading the supply and turning off the charger continued (2.3A seems just enough to power the idle laptop at ~20W and send 0.1C to the battery). This would just lengthen the time it takes the charging circuit to charge the battery to that threshold of 3V by an extra 10-15 seconds (because the powered laptop would discharge it a bit while supply is not powering the whole rig) does not seem unlikely. Now the period of 20s makes even more sense.

TL;DR: Your power supply is likely toast, and is no match to the load anyway. Maintaining the battery at below 10%¹ capacity is not optimal, but it is not likely to hurt it much, and it is probably still good. Borrow an adequate known good power supply, and try to boot the laptop.

Then, if it boots, but the battery does not charge, let it charge for a while (the laptop does not have to be on, just plugged in). If the battery has deeply discharged from just sitting there unpowered, it may take from hours to few days to recover, and then at some moment you'll notice it would take the charge normally. If it does not start charging after 3 days, well, shop for a new battery and have someone qualified replace it. Do not try it yourself if you do not know what you are doing, and do not think that you know what you are doing if you've seen someone doing it on YouTube! A lithium battery is literally an incendiary device if handled improperly, and a flat cell case is made of just thick foil, too easy to puncture and short at the same time.

If the machine does not boot, or at least shows any signs of life with a known good power supply, then please recycle it responsibly, sorry. :(

¹ This article on DigiKey mentions the preconditioning charge of 10% in the first paragraph under the “Carefully does it” heading; the full, 100% charge is the total area under the “battery current” line on the graph, and the preconditioning charge at 0.1C is the area under the part of the line from time 0 to the point where the charge current jumps from 0.1C to C. Since the battery sat idle for a while, it may have discharged completely through its natural leakage.
(Thanks to @MrEthernet for the request to clarify the original value of 20% for the initial low-current preconditioning phase; the value was, according to the op. cit., incorrect, and I updated it.)

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    "Maintaining the battery at about 20% capacity is not the healthiest thing for it." I read somewhere that 40% was the optimal percentage charge for Li-ion to minimize aging during storage at room temperature. Just wondering where the 20% figure comes into this? – Mr Ethernet Oct 23 '19 at 23:44
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    @MrEthernet, yes, as the engineer's lore goes, 40% is the optimal charge for longevity (the story I heard, below room temp and above freezing is better for long-term storage), 0 is very bad, and 20% is kinda the lower bound of okay. But I cannot provide scientific references for that; many engineers go with ballpark numbers in their heads that just work (or they think so; everyone is biased). Many a number come from mfg's data sheets and application notes, but the research behind them may be unpublished. Your note is very valid, thanks for the feedback, and I'll change my wording a bit. – kkm Oct 24 '19 at 1:03
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    @MrEthernet, I updated this part, and found an application article that provided a different figure, 10%. Thanks again for questioning the number, which was off. Ask three engineers, get three different values (and they all work in practice)--this is how we design things that "just work". Of course, this is partially tongue-in-cheek: if I were to design a piece of charging circuitry, I'd look for many more than just one article first. But then I would nearly certainly pull a number off the top of my head for some minor detail. – kkm Oct 24 '19 at 1:37
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    @Arjan usually Electrical Engineer, occasionally Electronics Engineer. – WBT Oct 24 '19 at 14:26
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    @PedroLobito, thank you for sharing your priceless opinion, highly appreciated! – kkm Oct 25 '19 at 9:56

My brother gave me a dead gaming laptop (Asus GL503V)

Here's the original AC adapter for that laptop:

enter image description here

As long as the adapter used also provided approximately 19.5V DC then it would not have damaged the laptop. A lower current than the 9.23 A the laptop is designed to draw would just mean slower charge times.

When i checked, the charger was 45W, while the laptop is 180W.

The supply was rated for exactly 25% of the demand. This charger would therefore take 4x longer to charge the laptop than the correct charger would have taken.

This situation would be just like trying to charge a modern smartphone designed to draw 2 A using an old charger that could only supply 500 mA. It would be completely harmless, as the voltage would still match, but charge times would be quadrupled as the power supply could only meet 1/4 of the device's power demands.

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    If it is too small the adapter will overheat under use of the laptop. Been there done that. – Moab Oct 22 '19 at 21:49
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    @Moab you solved this riddle. The power supply died here trying to keep up with the laptop's 400% power demands. The laptop lived and the power supply died. – Mr Ethernet Oct 22 '19 at 21:55
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    Luckily, the voltage was exactly the same, so the laptop itself will be okay. The adapter just couldn't handle the load. – Mr Ethernet Oct 22 '19 at 22:43
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    It might be harmless to the laptop but it has the potential to be destructive to the charger itself. Being permanently over current due to high demand could stress components and cause them to overheat. High current draw can also cause voltage to drop and would explain the original "would stop charging" problem. It is most likely the charger is dead, but the regular high/low voltage cycling could also have done something to the laptop charging circuit. – Mokubai Oct 23 '19 at 6:50
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    "This charger would therefore take 4x longer to charge the laptop than the correct charger would have taken." This is likely wrong. What is much more likely is that the laptop will still try to draw whatever its charging circuit is designed to draw, which is more than what the supply can provide, and the supply will either overheat or shut down itself regularily. There are smarter chargers / charging circuits from other brands that can adapt (maybe Dell), but I doubt this is the case here. The laptop does not know that it is a 45W supply, and can't reduce its charging current accordingly. – dim Oct 23 '19 at 11:54

Having 1/4 of the power rating as charger is very meager, and depending on what was being done with the computer, it may very well eventually have killed the charger.

However, note that 180W is the maximum that the laptop will consume, not the average. Most computers, most of the time, are mostly idle and consume very little power. Something around 10-20W is reasonable for "normal" stuff like writing a letter or surfing the web. My desktop computer here consumes around 30W in "normal" mostly idle operation (the monitor consumes twice as much!), and desktop computers are a lot less tuned to be energy-conservative than laptops.
Only when playing games, you would expect actual 180W being consumed. So, 45W should be just about enough for doing "normal" stuff and adding a little charge to the battery meanwhile.

Now of course, something that has to operate at 100% yield all the time will eventually break. That's not about "if", but about "when".

So, chances that the charger is actually broken, are high. Also, I've had cases where the socket (where you plug in the charger) became flaky after some time, that would also explain the charges-doesn't-charge-charges thing that you described. The laptop then probably ran until eventually the battery was empty.

That doesn't mean the battery couldn't have died or the mainboard couldn't have a defect. It's just not very likely. In any case a too weak charger will certainly not cause a defect on the mainboard (though it could always have a defect otherwise).

Also note that a laptop is of course a portable computer. That means it can, pretty obviously, run entirely without the charger, on battery alone. This somewhat mitigates the absolute need for a powerful charger.
Much like a Diesel locomotive, which in reality is not at all a Diesel locomotive at all. It's truly the precursor of a hybrid engine. The Diesel motor powers a capacitator (or battery), and an electro motor actually moves the train around, using energy from the battery. The Diesel is good at providing a steady influx of electric power, but it isn't particularly good at delivering stunt performance. The battery / electro motor combo, on the other hand side, excels exactly in this discipline. It only needs a means of getting steadily charged, somehow. Very similar, if you think about it.

The fact that a laptop can operate without charger altogether provides a recipe to find out what's wrong, too:

  1. Plug in charger (laptop stays turned off). Little red LED near charger hole goes on within a few seconds. If that happens, charger probably "works fine", something else is broken. Alternatively, plug it into someone else's (compatible, check voltage!) laptop. No red light means the charger is dead.
  2. Carefully nudge the plug a bit. If you get a red LED now, the socket is loose (trivial to fix if you have a bit of experience with soldering, but you will probably want to let a repair shop do it).
  3. Use any kind of compatible or halfway compatible charger (same form factor on plug, and same voltage, with no tolerance upwards, and 1-3V tolerance downwards) to charge the laptop. Leave charging over night, pull plug. Turn laptop on. Works or not? If it does work now, your charger is dead.
  4. Remove battery from laptop, plug in charger. Turn on. This should work, but you will not be able to run hefty stuff like games. If it doesn't work, the battery isn't the culprit. If it does work, replace battery.
  5. Try getting your battery charged somehow, or try getting a replacement charger somehow (borrow from a friend? ask in a store?). If any of the above works with the now charged battery or the other charger, laptop is dead.
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  • I guess it might indeed have killed the charger, especially when the battery was empty while the computer was used. Like Apple MacBooks would reduce processing power when the battery was removed, and the only power source would be the small charger: "This prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide". – Arjan Oct 23 '19 at 11:40
  • Considering it's described as a gaming laptop, I strongly suspect it wasn't just used for writing letters. That charger is seriously suspect. – Mast Oct 23 '19 at 13:44
  • nitpick: EMD locomotives don't have batteries. The engine(s) runs a (very large - easily half the power output of the engine) air compressor and a generator, the generator runs the motor(s) and other electrical loads. – Phil Oct 23 '19 at 20:55

Try removing the laptop battery and connecting the AC adapter. If it powers on, the issue was with the battery. A damaged or spent battery may prevent the system from powering on, but any laptop should work with no battery and the AC power connected.

You probably can go into the firmware menu (BIOS or UEFI) and check the battery health, if you can get it to power on.

If it does not, the issue could be the motherboard or charger. The cheaper component to replace will be the charger, so try getting another one of those.

Wrong chargers can do a number of things (such as generate firmware error messages or cause the laptop to run more slowly), but constantly starting/stopping charging isn't typically one of them.

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  • Wouldn't they need to use a larger AC adapter? If its a 180W laptop and only a 45W adapter it may not be able to provide enough power to turn on. – Sam Axe Oct 22 '19 at 21:46
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    Exactly. That replacement charger was completely inadequate. The laptop is expecting something than can supply over 9 Amps! – Mr Ethernet Oct 22 '19 at 22:03
  • I just tested this out, but sadly, it did no work, @Sam Axe what you said makes a lot of sense and i guess you're right, but i'm not sure. – Kakuhiry Oct 22 '19 at 22:07
  • This model has a non-removable battery. See youtu.be/y6jIMcA6sLA – kkm Oct 23 '19 at 11:03

With today's smart batteries and chargers I'd guess what happened is that the laptop simply rejected to (wrong) power supply. My Dell G3 will ignore external power unless it has a Dell powersupply with at least 180W plugged in; an HP powersupply with 230W didn't do anything, and it was the same with a Dell 60W powersupply.

Laptops do this to protect both the battery and the laptop itself. Dumb thing about it is you need the original powersupply, a noname-brick or powersupply from another laptop (although it might work, given that the voltage and amperage are ok) will be rejected and the laptops simply runs on battery (until it's exhausted).

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