-1

I have this laptop:

http://www.newegg.com/Product/Product.aspx?Item=N82E16834233058

It came with a pretty large and heavy power supply, so I am trying to replace it with a smaller one. The reason why it's so heavy is because it outputs 19.5V at 7A max. That's a lot of power. I plugged my laptop to a desk power supply and measured the current going in at 19.5V when I simultaneously copy file from partition to partition, download from the internet and play a very demanding video game engaging the NVidia graphics card. Maximum input was 4A - it never peaked over it. When the graphics card is not engaged, the input is about 1.5A. My question is, is it safe to replace the power supply with one that outputs maximum of 19.5V at 5A? What happens if, theoretically, the current draw is momentarily higher than 5A? I guess it would just turn of charging of the battery and start sucking the extra needed power from the battery, right? In other words, I should be safe using a lower amperage power supply, correct? I want to make sure my logic is sound before I do this. Thank you!

Community
  • 1
pkout
  • 153
  • 1
  • 8
  • Modern laptops can sense what type of adapter is plugged in and refuse it, or disengage some functions such as battery charging when not enough power is available. If the 5A adapter claims to be compatible with this specific computer, it will work with reduced performance. Otherwise it will not. – venny Sep 17 '14 at 17:26
  • I was downvoted, I guess because this question was asked already. Is there a way to merge this question with the other one or should I just delete it? – pkout Sep 17 '14 at 17:58
  • I don't think this is a duplicate of the power supply question. You measured the current usage of your laptop and found it to be less than the supplied adapter. This question is more asking whether it's OK to assume that lower current usage by the laptop allows you to use a smaller adapter, which in theory it does. However nobody except the manufacturer can state definitively whether there is a reason for the oversize supply. – JYelton Sep 17 '14 at 18:04

1 Answers1

2

If a lower-current power supply was suitable, the manufacturer probbaly would have saved the extra cost and provided a lower-current power supply.

Though, it's entirely possible that a different model computer made by the same manufacturer does use more current, and it was more economical for the manufacturer to order a gigaton of 7A supplies rather than a megaton each of two different supplies.

I can't speak as to how exactly your laptop functions when it comes to charging the battery versus using power from the external adapter, it might or might not have the smarts to alternately charge or use the battery depending on power supply and demand.

If you use a lower-current supply and your laptop encounters an instance where it needs to draw more, but cannot (because the battery isn't present or the charging circuit isn't appropriately designed), then you could damage your computer.

So, while you might be fine using a lower-current supply, be prepared to void your warranty or worse.

JYelton
  • 32,302
  • 33
  • 134
  • 249
  • Okay. Thanks for the answer. I tried one lower power adapter that I have here (same voltage, lower amperage). It worked, even charging worked. I just wasn't sure if it could damage the laptop long term during power spikes. – pkout Sep 17 '14 at 17:56
  • It may be that the laptop is perfectly fine with it. The battery might charge more slowly, of course. I'd base my decision on how expensive and new the laptop was. :) If it's worth a lot to me and new, I'd use only the correct adapter. – JYelton Sep 17 '14 at 17:59
  • If you saw the massive, heavy beast adapter that came with it, you'd give it a second thought :). Thank you for your thoughts on this! – pkout Sep 17 '14 at 18:01
  • Might I suggest writing GigaByte an email to their customer support? A definitive answer from the manufacturer would set your mind at ease. – JYelton Sep 17 '14 at 18:02
  • I am quite familiar with corporate behavior and their answers. They will very likely discourage me from using another adapter even if it's viable. – pkout Sep 17 '14 at 18:07
  • @pkout yes, they will discourage it, lest you do something different and something goes wrong and you sue them. – KyranF Sep 17 '14 at 19:24