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I have a two year old laptop that has spent most of it's life in a third world country where the power is very dirty*. Does the dirty power shorten the life of the battery or will it have no effect?

I'm no battery expert but my gut feeling is that it won't make any difference because the transformer will only give my a specific voltage regardless of the input voltage.

Is this correct or will the transformer be subject to the principal of garbage in, garbage out?

*Dirty as in subject to spikes and/or brownouts in the power supply.

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up vote 6 down vote accepted

Short answer: no, nothing will happen because of dirty power.

Notebook power supply does not contain just a transformer; it is a switch-mode power supply, and that involves much deeper level of conversion, output control and efficiency. For example, typical supply can work both on 220V and 110V networks. Moreover, there is another switch-mode converter inside your notebook which charges the battery, so the power that charges the battery is "double-converted". Basically it means that any spikes were filtered away.

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Lightning would still kill it, though. – LawrenceC Jul 10 '12 at 19:41
I bought a new (unoriginal) laptop adapter and my cursor started jumping around. I read this!topic/chromebook-central/… and asked myself the same as OP, but how can your answer be true, if it affects the trackpad? – Thomas Jensen Mar 9 '14 at 18:30
@ThomasJensen This is interesting. It means that the power supply in the notebook was unable to filter the input. I would not expect Chromebook's supply to be that bad, though... Do you perhaps have an oscilloscope? – whitequark Mar 13 '14 at 9:35
@whitequark I live in Denmark, which I would expect had very clean power, and it happens in different parts of the country as well. So I don't suspect the source to be the problem. No I sadly don't own an oscilloscope. The laptop is a Thinkpad X1. The question remains; Does it hurt my battery/laptop? Should I get rid of the adapter? – Thomas Jensen Mar 14 '14 at 10:39
@ThomasJensen No, I meant the input of the laptop itself, connected to the output of your power supply--not your mains. I would get rid of it. I don't think anything has happened to your laptop yet, but supplies of such incredibly horrible quality are prone to catastrophic failure. – whitequark Mar 15 '14 at 11:21

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