Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Battery on my laptop is 4%, I don't have original power supply at the moment and I have some work to do.

Is it safe to ask a friend to give me his power supply from another type of laptop?

What parameters to look for to see if this is possible?

share|improve this question

migrated from serverfault.com Nov 13 '10 at 18:26

This question came from our site for professional system and network administrators.

    
Do you mean "power cable" or "power supply" (with its associated cable(s))? –  Dennis Williamson Nov 13 '10 at 19:42
    
Sorry, I meant the whole thing - cable from the wall to the laptop. –  kliketa Nov 14 '10 at 15:21
add comment

5 Answers

One size does not fit all. Buy something like the thing at picture below (would replace to CC version later), pick a matching connector, set a correct voltage.

Lower power (e.g. 60W instead of 90W) is OK, just the battery charge time will raise. Same for higher (used to feed 30W netbook with 110W supply). Voltage should be the same!

alt text

share|improve this answer
add comment

I have used a 90w power supply on my dell and it seems to charge much faster than my current 65w unit. Since my 65w unit blew it works very well with the 90w unit. Hope this helps!

share|improve this answer
add comment

Same power ( voltage and Amps )

Well its doesnt have to be perfect but similar..

As an example

(19.5V - 7.7A) 20V - 7.8A is fine..

Obviously the power adapter to connect should fit / be the same

share|improve this answer
    
Better off a little higher on the amperage and voltage than a little lower, although for short use, it shouldn't make much difference. Try to avoid large variances. –  MaQleod Nov 13 '10 at 18:58
add comment

Obviously, the connector must fit. Other than that, the voltages need to match. There is some tolerance, but it's hard to give a solid number of what will still work and what might even harm your computer. Lower voltages are safer, but 5% deviation will be fine either way.

Another thing to look out for is the polarity as reversing it could be damaging, probably isn't but a power supply with the wrong polarity definitely won't work. Luckily, it is very uncommon to find laptop power supplies that do not adhere to the rule of the inner terminal being positive.

Current is largely irrelevant. How many amps are supplied depends on the load, not on the PSU which simply specifies the maximum current it can handle. If your laptop draws more power than can be supplied, the machine will either shut down or draw power from the batteries. Worst case scenario for a current rating too low: you need to power the machine down and wait for the batteries to recharge. Worst case for 'too high' a current, the recharge crazy fast.

share|improve this answer
add comment

My Dell D510 is OK with another Dell power supply. Original was 19.5v with 3.3 amp output. The 'extra' power supply is 19.5v with 4.6 amp output. Your mileage may vary. Take pictures of your laptop on fire if it doesn't work out, and let us know. Since, I'm only supplying a single data point. My guess is, that you can probably be within about 0.5v tolerance and 50% of the amp output... but I"m only guessing on that. Oh yeah, you'll find that the physical connector varies among manufacturers, so you'll need a 100% match there.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.