Can I use a charger with the following values:

Input 100-240V 1.5A Output 19V 2.40A

To replace

Input 100-240V 1.6A Output 19V 3.42A

  • Check my answer below but it would be more useful if you posted what you are powering and what the specs were. – cbmeeks Jun 17 '15 at 20:02

First, you need to check what your device REQUIRES.

If the device requires a steady 3.42 amps and you're providing only 2.4 amps max, then the device (laptop?) will attempt to pull more current than the PSU was equipped for. Which could result in PSU failure, laptop failure or even worse, a fire.

Now, assuming the device ONLY needs to pull 19V and 2 amps, then you are within spec. And that would probably be OK. But I always prefer a safety margin. If a device requires 2 amps I like to make sure the PSU can provide 3 or more.

NEVER assume that because two power supplies fit, are from the same manufacturer, etc. that it is safe to use.

ALWAYS ALWAYS check the specs on the device you're needing to power.

  • Something I'd like to add to this answer...one thing I should have mentioned is to also check the polarity of the plugs!!! Many adapters (at least in the US) have center-positive polarity. Which means the "tip" (or center) of the barrel jack is the positive voltage and the surrounding shield is negative. But this is NOT guaranteed! There are some devices and PSU's that are center-negative. Reversed. If you plug the wrong polarity in, and your device doesn't protect from reverse polarity, you will more than likely destroy said equipment. I can't stress this enough. Do your research. – cbmeeks Feb 5 at 16:05

A similar question, at one point marked as a duplicate, focuses on a voltage difference between the original charger and a replacement. The answers on that one do a good job of addressing that issue. Here you're talking about 1/3 lower current rating, which is a different issue.

Short Answer:

  1. A charger with that much lower a current rating is unlikely to be adequate.
  2. The determination should be based on the specifications for the device being powered. If those specs are unavailable, use a charger at least the capacity of the original charger.

Longer Answer:

The current rating is a capacity. The charger will supply only what the device requires, up to the rated capacity. You don't need to worry about a charger with a higher current rating, but a lower rating might, or might not, be a problem.

The chargers are often "generic", designed to work with a range of models. The capacity of the original might be more than your device needs, in which case the replacement might be fine. In this case, if your device could actually work with a 2.4A charger, the originial would have been nearly 50% more than required, which seems unusual.

The only situation in which you should use a smaller charger is if you can determine that it meets the specifications for the device. Your device should have a sticker on it that shows its power requirements. If the sticker is no longer readable, you may be able to get the information from the user manual or the manufacturer's web site. The replacement must meet or exceed the device's amperage requirement.

If you use an inadequate charger, you will overload it, which could damage the charger or cause its overload protection to shut it down. Even if it does work, you would probably be unable to both charge the battery and power the device simultaneously. The charger would also run very hot, which could shorten its life.

If you are unable to determine the laptop's power requirements, go one of two routes:

  • Buy from the device manufacturer the replacement that they currently sell to support your model device. If its rating is a little less than the original, it probably means that the original had more capacity than required (and at least you would have recourse if it isn't adequate). If the replacement has a lot less capacity, like your example here, I would double check with the company's tech support.
  • The other route is to buy a third party replacement, in which case, go with a charger rated at the same or greater current than the original charger. Ignore any marketing claims that a lower capacity one is designed to work with your model device.
  • 1
    The OP didn't mention anything about what the power requirements actually are. Looking at specs on two different PSU's is pointless. We need to know what the device is and how much power it requires to know what kind of replacement is OK. Not the manufacturer. – cbmeeks Jun 17 '15 at 20:00
  • @cbmeeks: Good catch about the laptop specs; that's the definitive guidance. I added it to my answer. However, if those specs are unavailable, there is no reason why the original charger cannot be used as the basis for a replacement (in which case a smaller one like described in the question should not be used). If your point is to not try to guess at whether a smaller replacement will work, I agree. – fixer1234 Jun 17 '15 at 21:15
  • 1
    I disagree. The OP is clearly asking if a PSU with LOWER SPECS can replace a PSU with LARGER SPECS. i.e., can a PSU rated at 2.4 amps replace a PSU rated at 3.4 amps. Well, in generic terms, NO. I have to assume that whatever device that needed the 3.4 amp PSU needed it because it, well, needed somewhere close to 3.4 amps and providing only 2.4 amps may not work. The difference is huge. Now, I'm not saying it won't work for the OP. I can't because we still don't know what the requirements are for the device. – cbmeeks Jun 18 '15 at 14:13
  • @cbmeeks: We're not in disagreement. The size difference was the reason for my answer, as mentioned in the 1st paragraph. A charger that much smaller probably is not adequate and my advice was to get one at least the original size in the event that the actual device requirements cannot be determined (but to base it on the device specs if available). We're saying the same thing, our answers just have a different focus. The only place we differ is that I don't think an undersized charger could damage the device or cause a fire, so I didn't state that in my answer, but the advice is the same. – fixer1234 Jun 18 '15 at 15:19
  • OK, I can see your point. But, when you say "I don't think an undersized charger could damage the device or cause a fire", then that's where I disagree. I've seen cheap wall-warts get SUPER hot because somebody thought "the plug fits so it must work!". Only to find out the device attempted to pull 1.5A and the unregulated wall-wart was only rated at 0.5A. But again, I think we both have the same intentions with our answers. So, no worries. :-) – cbmeeks Jun 18 '15 at 19:57

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