Matching power Supply volts and amps to laptop

Starwatcher55

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Mar 10, 2013
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I have a dell laptop. I having a power issue. The power lights so not turn even though it is receiving power form the supply. I wonder does their amps on the supply have to match the amps for the laptop or can it exceed the requirement. This laptop was produced in 2004
 

unksol

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Sep 12, 2011
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the current capacity of the supply just has to meet what the load will draw. It doesn't matter if it exceeds it. Voltage needs to be relatively close.

If it's from 2004 it's not worth messing with at all and probably just died from old age anyway.
 

RetiredChief

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Feb 22, 2007
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You have two posts open for this question.
As posted in your other post:
Two Things:
1) The Current (Amp) Ratings on the for the AC adaptor is ONLY stating that the rated Voltage can be supplied at UPTO the specified amperage..
2) The Ac adaptor will only supply what current is required by the laptop upto the max rating. ie The current, upto specified is dependent on the load, not the charger.
3) as long as your laptop current draw is under that specified on the charger; voltage polarity is correct, and plug/jack mate properly - you are fine.

My charger for a i5-2410 17" laptop w/ 540M dGPU is rated 19V @ 4.74A.
Max wattage: Charging battery and playing a Blu-ray move 60 Watts.
Using a eff rating of 80 % this means that the AC adaptor is ONLY providing approx. 2.5Amps

Added: unksol - depends on what def you use for close - LOLs
"Voltage needs to be relatively close."
Most laptops will operate from the Cigarette lighter in autoes. This voltage is 12.6 ->14 Volts.
The voltage supplied must be above, the greater of, the Voltage required by the MB (typically 12V) and the voltage required to charge the Batteries. Laptop batteries are typically about 10.9 ->11.1 Volts (depends on the type of Li-ion battery or for OLD laptops Ni metal Hydrioxe).
What happens is the Laptop is based on Power, so as voltage input decrease (up to a min value ie 12.6) the current draw required will increase. A 8 Amp brick at 12.6 V would most likely work - Do I recommend that, No - Reason is that the charging circuit must work much harder - lower eff.


 
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