Laptop AC Adapters

[ianbergman]

Typically, for a 2nd AC adapter, I've thought that matching the voltage was important, and the amperage less so. My impression is that about the only result is that a mismatched amperage tends to wear out the battery a bit faster.

Does it matter at all? Or am I a fool and should I make absolutely sure that additional AC adapters for my laptops match in voltage and amperage to the original?

 

[Mark R]

Match the voltage as closely as possible.

The current (amps) rating on the PSU should equal or exceed that of the original. If the new PSU is too weak it may sizzle when the laptop tries to charge. If it's too strong then there isn't a problem, except maybe it will be bigger, heavier and more expensive.

 

[Chu]

Originally posted by: ianbergman
Typically, for a 2nd AC adapter, I've thought that matching the voltage was important, and the amperage less so. My impression is that about the only result is that a mismatched amperage tends to wear out the battery a bit faster.

Does it matter at all? Or am I a fool and should I make absolutely sure that additional AC adapters for my laptops match in voltage and amperage to the original?

You don't want to get the voltage close - you want it SPOT ON. Electronics are EXTREEMLY sensative to voltage changes. As for amperage, you want greater then or equal the one your replacing.

Oh - and about the plug - not all plugs have the same polarity! Be careful.

 

[imported_raybay]

Your statement as to voltage and amperage is essentially correct. For short terms of just a few days, you can be off by as many as two volts and be ok. Longer use will damage either the battery or the adapter. Many technicians claim that you can go one way but not the other... trouble is, I cannot remember whether you can increase the voltage over standard or decrease it. The computer itself is usually not too sensitive to voltage or amperage differences.

 

[lobadobadingdong]

voltages are rated +/-X% typically for PC devices the range is +/-5% allowed deviation your amps should be the same or more, for example if you have a 12V 15A device you need 11.4 to 12.6V output and 15A DC input, if you have a DC input of 20A or 30A that's fine, but the higher output devices will put out more heat and weigh more.

 

[Chu]

Originally posted by: raybay
Your statement as to voltage and amperage is essentially correct. For short terms of just a few days, you can be off by as many as two volts and be ok. Longer use will damage either the battery or the adapter. Many technicians claim that you can go one way but not the other... trouble is, I cannot remember whether you can increase the voltage over standard or decrease it. The computer itself is usually not too sensitive to voltage or amperage differences.

+2V:Q Most laptops have the bare minium when it comes to power regulation. Feed that much extra voltage to it and your just BEGGING for trouble - one or two days or not. Considering the most I've seen wall sockets vary is ~10%, a 120V;15V transformer would correspond to 132V:16.5V, so I guess you could get away with an extra 1.5V - but if you plug into that same socket with your new out of spec AC adaptor you now have 132V:18.15V, 3.15V out of spec! This is REALLY DANGEROUS. Spend the extra bucks and just get the right AC adaptor please.

-Chu

EDIT : Way over or Way under really depends on the particular part. For way over, your really putting stress on your components, though eventuially you'll hit something with a voltage ceiling. Under is really dangerous for components like flip-flops, which might not trigger correctly - which generally isn't dangerous for life but will corrupt data.