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My laptop charger (Toshiba Satellite L850 18U - 19V 4.74A) has been broken. So I bought a new charger - Trust 90W charger. According to the new charger's packaging it is suitable for my laptop. But when I opened it on the product label it says that the charger is 19.5V 4.62A. Do you think that it is save to use it? As the packaging says that it is suitable for 19V 4.74A.

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  • You have to look at the bottom of the laptop for the input rating. The 19.5V vs 19V will not matter (it is a small enough difference); as long as the current rating on the charger is at least as much as the current rating printed on the laptop it will be fine. Dec 1, 2014 at 20:01
  • The chargers are "generic"; the same model is used for various laptops even with the OEM chargers. The 19.5V is close enough to 19V, it won't make a difference. The 4.62A is slightly less than 4.74A, but 4.74A was likely more than the laptop actually required. If your laptop is heavily expanded and was drawing the limit on the old adapter, the replacement will get extremely hot. In that case, return it based on mislabeling that it could actually handle 4.74A.
    – fixer1234
    Dec 1, 2014 at 20:12

4 Answers 4

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To be absolutely safe:

  • No, you shouldn't use chargers with different voltages at all and if you do, you will most likely void the warranty of either the laptop, the charger, or both. That also goes for the safety guidelines so if anything exploded in your face, YOU would be responsible. (Except maybe the charger manufacturer could be if they officially stated it's compatible with your model)

If you don't care about warranty and are ready to be responsible for your safety:

1. Voltage: 19.5V and 19V is a relatively small voltage difference. It is most probably safe to use as long as:

  • The current of the charger is the same or higher than that of the laptop. (Which in this case is not, but then again, 4.74A and 4.62A is a relatively small difference) To explain a bit more:

    • The output power (Amps * Volts) of the original and the new charger differs in 0.6 Watts, the 19.5V charger having more output power. That's negligible.
    • Laptops usually don't draw the full power from the charger even when in use and being charged at the same time. The original charger was ready to output slightly more power than needed so even then - only, let's say, 4A were drawn. Which is well enough for the new charger to handle. Though in case you were to do heavy computing (gaming, rendering 3D or videos, or similar), and charging the laptop at the same time, it might need to draw the full power, in which case the charger wouldn't supply enough for it's rating and start to get very or extremely hot and your laptop would start to slowly discharge even when connected. In that case, you should immediately stop doing what you were doing and disconnect the charger.
    • Most chargers from trustworthy companies have a fuse that would shut the charger down in case of extreme overheat (as in extreme power draw), but you don't want to risk anything.

2. Current: As explained above, the current rating of the charger should be same or higher higher than that of the laptop. (To understand - Laptops draw current from the charger as needed. Chargers don't push current inside laptops. So if the laptop is fully charged, it takes ~0A from the charger even when connected.)

3. Size: The charger's connector needs to be exactly the same size as the old one (meaning that it needs to fit the laptop connector), otherwise it might either not fit at all, or if it does, you might break the laptop's inside connector and make it unusable even by original chargers.

4. Polarity: The polarity of the charger connector and the laptop connector (or the original charger connector) must be the same. It most probably is, the industry standard is "+" on the inside pin and "-" on the outside. But to be sure, check for polarity on both the charger and the laptop. There should be a picture similar to this - polarity image

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I’ll attest to it being perfectly fine to use a 19.5v adapter on a 19v machine.

I have had countless of laptops and All-in-One (AIO) machines, and have had to deal with missing power bricks many times. After looking into this over 10 years ago, I was advised the same as those have found here; most power adapters never put out exactly the voltage they spec and most error on the high side.

It had been many years since dealing with this and recently noticed my high end Acer AIO had a generic LiteOn brand adapter that was rated less wattage than what the machine specified. It needed 9.47A at 19v. It concerned me that I was shorting the machine some watts under the recent high loads I was putting it under. Although, it never had any BSOD or other issues.

My high end Dell laptop had the same plug that would fit in the Acer but was 19.5v @9.23A. I plugged it in and it ram it just fine under full load for hours while rendering.

If you do the math and multiply the two figures together, on each one, you get the same exact watts. I even checked the voltages. The Dell 19.5 laptop adapter was ready 19.34 and the one I had been using on the Acer AIO (that called for 19v on the machine and stated 19v on the adapter) read 19.25A.

One thing I did learn when bench testing some fans and wanted power from a PC power supply I had laying around, is the following. Just because you jump the green wire on the ATX plug and turn the power supply on (old trick that has been know for decades), and you may get the 12v or 5v that you need, the power supply will not be able to go into full voltage regulation unless the power leads have a certain minimum load on them. If you ever want to turn a PC power supply into a bench power supply or one for another purpose it’s good to research this. The reason I bring that up is that maybe these external power adapters are the same way. Maybe you are reading incorrect voltage, when you have it plugged to the wall but not plugged into the laptop. Maybe the voltage regulates more to the 19v or 19.5v that the adapter specs? Either way, thankfully these machines can work with a range of voltage.

It’s apparent that the motherboards must have their own voltage regulators onboard since the CPU and other components really need a steady voltage or they will get fried. I doubt they rely on a power adapter plugged in far from the machine and a quick disconnect plug and battery and all other factors that can cause power fluctuations.

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I took out my digital multimeter and measured the output voltage of five of the 19-volt adaptors I have with the multimeter setting at 20 volts. I also measured five of the 19.5-volt adaptors I have. All the ten adaptors had output voltages above 19 volts but none of them, not even a single one, had an output voltage above 19.4 volts. Two of the 19-volt adaptors even had higher output voltage than the 19.5-volt adaptors.

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    The output voltage with no load attached is not a good indicator.
    – sawdust
    Mar 30, 2020 at 5:13
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Not with some laptops especially DELL Latitude 7390 Model. Even with DELL laptop chargers of 19.5V/65 Watts or 90 Watts (recommended by manufacturer), if the output voltage becomes 20V DC, the pop-up error message "Replace with compatible charger" is activated and battery charging will stop. The tolerance limit looks like 19.5 +/- 0.3 Volts. With incoming AC supply exceeding 240V AC (charger rating 100V to 240V AC),the output voltage becomes 20V DC and the laptop stops charging the battery.

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