Electrical Question - Laptop adapter Input A

i have two laptop adapters, one i received due to the oem one buzzing

they both have the same output rating BUT the INPUT is different by ONE AMP.

the oem INPUT is 100-240V~, 50/60Hz, 2.5A
the other INPUT is '', '', 1.5A

what is the difference (besides the one amp difference =P), which is better? is it safe?

 

No it probably isn't...the power rating isn't going to be as high. If your notebook draws too much power you could burn the new AC adapter out.

But just to be sure, what notebook do you have?

 

gateway MX7525, it is a AMD 4000+, i also undervolt too

 

That PSU rated at 1.5A input will be fine unless you have some monster of a laptop. The power would still be over 150W at 110V. It is the output voltage and current which matter and the replacement should have a current equal or larger than the original.

[I have just looked at the specs for the PSUs for my notebooks. The Q35 has a small 60W PSU rated at 100~240V, 1.7A input; 19V 3.16V output. The X60plus has a bigger 90W PSU rated at 100~240V 1.5A input; 19V, 4.74A output. Strange that the bigger PSU has the smaller input current, but I won't lose any sleep worrying about it.]

John

 

The above just points out the Efficiencies differences of those adaptors

The first one to produce it's rated output will consume 300 Watts ( 120 Volt X 2.5 Amps)

The second one will consume 180 Watts (120 Volts X 1.5 Amps)

The first one consume more power for the same output which means that the excess power draw will be converted to HEAT.

With higher efficiency, less energy is wasted in Heat and your electric bill is lower.

If I look at the 3 adpaters I have access to, here is the breakdown;

Calculations are based on 120 Volts AC input

LG S1 Adapter. Input 100 to 240 VAC @ 1.5 Amps (180 Watts)
Output 19 Volts DC @ 4.74 Amps (90 Watts)
Efficiency = 90 / 180 = 50%

Dell Latitude C400. Input 100 to 240 VAC @ 1.2A (144 Watts)
Output 20 Volts DC @ 2.5 Amps (50 Watts)
Efficiency = 50 / 144 = 34.72%

Voodoo Envy M855 (Mitac 8350)
Input 100 - 240 VAC @ 2.0Amps (240 Watts)
Output 19 Volts DC @ 7.9 Amps (150 Watts Max)
Efficiency = 150 / 240 = 62.50%

Best regards

frenchnew

 

To attain the power rating of each adapter the power equation (P=IV), should only be applied on the output of the adapter, and not the input. The adapter will only use the amount of energy that is required by the notebook, and not more. Heat is given off from components within the power supply that covert the AC power to DC. Basically, the AC adapter is a transformer. Transformers are very power efficient, and don't give heat (and energy) out that isn't being used.

 

Yes. These modern switch mode PSUs are quite efficient. I would guess around 80% to 90% which means that they only emit around 10W as heat (and that is only when heavily loaded). If there was 100W to dissipate they would need a fan and/or be too hot to hold. The point I was trying to make in my earlier post is that the input current values seem to be nominal. Perhaps they reflect a temporary surge when the PSU is plugged in.

A traditional transformer would be much less efficient and about 5 time heavier (I had one about 12 years ago for an external CD-ROM drive and the transformer weighed more than the drive).

John