0

Many a times I leave the laptop connected to the charger with the switch on for the entire day. When it becomes fully charged does it still consume electrical energy?

MrAP
  • 487
  • 1
  • 5
  • 13
  • 3
    You are asking if a powered-on laptop consumes electricity? – Bryan Boettcher Dec 20 '16 at 14:42
  • When the laptop is fully charged does it still consume electricity? – MrAP Dec 20 '16 at 14:43
  • @Antonio No its not a duplicate. That question addresses what happens when the switch is on but nothing is connected with the charger. My question is different. – MrAP Dec 20 '16 at 14:54
  • 1
    @MrAP - *"what happens when the switch is on but nothing is connected with the charger"* - That is not what you asked. You need to be very clear with your question. Two sentences is rarely ever enough. – Bort Dec 20 '16 at 15:21
  • Ah, ok. This depend from laptop. For example my Thinkpad (and some Lenovo Ideapad) has a battery life optimization system that defines the levels (thresholds) of charge and discharge. If battery is over the upper threshold battery won't charge also if you leave it plugged into mains. – Antonio Dec 20 '16 at 16:08
  • Yep it does, quiescent current – Voltage Spike Dec 20 '16 at 19:02

2 Answers2

5

Yes, some energy will still be consumed.

Assuming the laptop is switched off (not in sleep mode) and the battery is fully charged, it will consume very little energy (a few Watt perhaps).

When in sleep mode, the laptop keeps the RAM powered so it will consume somewhat more power.

But do not neglect the power adapter (many call this the charger but it is not, the charging circuit is inside the laptop). If the power adapter is of good quality it will also consume very little energy.

You can easily check what is taking significant power as this power is converted into heat. So an inefficient power adapter will get warm or even hot when you charge the laptop. When the laptop is off the power adapter should not feel warm (allow it some time to cool down after charging though).

Samuel
  • 11,811
  • 31
  • 51
Bimpelrekkie
  • 80,139
  • 2
  • 93
  • 183
  • Why if the laptop is switched off it draw some energy? I see it happens on my notebook (Lenovo ThinkPad E550), fully charged, after a week the battery could be at 50-60%, but I can't understand why it "eat" some battery when I leave it unused. – Antonio Dec 20 '16 at 16:11
  • Even when it's off the laptop is still partly on. e.g. it may need to keep something powered to detect the power button. It may be looking for wake on LAN packets. And the battery pack monitoring circuits are also always powered. But none of this should take much power at all, no where near 50% in a week. Are you sure it's off and not in sleep mode? – Andrew Dec 20 '16 at 17:17
  • A laptop cannot be switched "off", unless you remove battery, and disconnect the charger from AC mains. There is always some standby mode inside the system's ICs, which makes these power buttons to react to pushes and set internal signals signal "on" or "off". There are only specified system states, S0 to S6, per ACPI specifications. https://arstechnica.com/civis//viewtopic.php?f=8&t=354552 – Ale..chenski Dec 20 '16 at 19:58
1

Yes it will still consume some energy. It takes some energy to operate the charger itself.

The charger will draw the most power from the power mains whilst it is in heaviest part of the charging cycle. As the battery becomes charged the line load will taper off to the idling mode.

Note that there can be wide variation on amount of idle power that various chargers can consume.

Michael Karas
  • 56,889
  • 3
  • 70
  • 138
  • Actually, there is no wide variation. A consumer product must pass variety of certifications, and standby power consumption is one of them, and for the last decade the level was <500mW. Making standby consumption less is not economical. So all manufacturers "optimize" their product to this level. This answer clarifies the statement, http://electronics.stackexchange.com/a/274233/117785 – Ale..chenski Dec 20 '16 at 18:03
  • @AliChen - You are correct IF you can vouch for all manufacturers performing the necessary tests and obtaining the certifications. I venture to comment that there are plenty of low cost sources for power adapters that place fake certification labels on the product and sell them to consumers. This has become way more prevalent in modern times where consumers, looking for the cheapest prices, do their purchasing on line where source to customer knows no national or regulatory boundary. – Michael Karas Dec 20 '16 at 19:38