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All AC current in the following has been measured by an ordinary digital multi meter, the Conrad Voltcraft VC220. It does not measure RMS. Doc states "displays RMS for sine wave input". Likely it measures peak and multiplies by 0.707. It has not been verified what kind of AC load the Mains adapter is, whether close to ohmic resistance (power factor near 1.00) or just eating current from top of voltage waveform. To get peak current, all AC current readings have to be multiplied by 1.41. But no easy way to compute RMS from peak. Have to know waveform - currently unknown.
Can we compute power differences from current difference? Difficult because we need to know the voltage at time of current, all moving targets. Charging current flows usually on rising egde near peak voltage, continues for smaller time after peak passed.
Computation of electrical power by "P = I * U" is only valid for RMS values of I and U.
The AC current readings are still good for comparision, to find increase and decrease, and give a feeling how much.
2011-06-22 Try some AC measurements. Multimeter VC220 fused mA ranges seem broken. 20 A range AC gives impressive reading of 0.02 to 0.06 as soon as a single cable is connected, or both, but no current flows. Little current seems to reduce to 0.01. 20 A range reading is 0.01 with little current flow and hands off, but flat hands left and right put at VC220 is 0.15. Impressive. Accu not charging. Mains voltage by VC220 is 228 V. CPU will soon not run at 1.33 Ghz, but be 800 MHz limited I guess. WIRELESS=ON, by software enable WWAN, disabled WLAN, disabled Bluetooth. Energieoptionen "Harddisk"="never off", CPU=Leistung. ############ Consider efficiency of Mains adapter to calculate final power inside VGN-P! Do later! 0.05 waiting in WinXP bootloader. 0.05 while booting. 0.03 idle WinXP desktop driving only external 1920*1080*16bpp*60Hz, sometimes 0.04 0.04 2* Calculator computing faculty. 0.04 1* Calculator, 1* h2testw.exe Write to internal HDD. Can I expect to see anything? 1 W at 228 V is 0.00044 A. 0.04 A means 9.12 W and can be true. But working at last digit is futile. Fixed broken fuse temporarily. Using 200 mA AC range now. Hands off. 01.3 Mains adapter disconnected from mains cable. Reading due to light in Mains switch. Closed switch, read 00.1. Light is 1.2 mA or 274 mW. 13.3 to 13.4 Mains adapter alone. VGN-P disconnected. Subtracting 1.2 mA, got 2.76 W Standby power. SONY says 0.3 W max on web. Needs interpretation. I believe the 0.3 W because of cool feeling of device. LED in plug to VGN-P is definitely less than 20 mA at 10.5 V or 0.21 W. It surely eats current from top of voltage only, no Power Factor Correction. No easy way to open it, because no screws, either snap-closed or glued. ########### 14.3 to 14.5 VGN-P OFF, but connected. Difference to previous is 1 mA. Comparing with 2010-01-14 DC result of 20.4 mA at 10.5 V is 0.214 W. Have 1 mA reading increase at input. ... REMARK: Hands on VC220 the 13.3 reading reduced to 12.8. 40.2 idle WinXP desktop driving only external 1920*1080*16bpp*60Hz 43.0 1* Calculator faculty 44.x up to 46.0 2* Calcu facu 48 to 49 1* Calcu facu, 1* h2testw reading internal HDD already present test data, writing nearly same, may go up to 50.x for short time It is difficult to get a truly idle system, because frequently WinXP wants to do something in background, accessing HDD short time. No Explorer window any more, but only "Eigenschaften von Anzeige" open. 40.0 to 40.3 1920*1080*16bpp*60Hz 40.4 to 40.8 1920*1080*32bpp*60Hz Approx 0.4 mA difference is 100 mW, trusting last digit of VC220. 51.3 to 51.6 extern 1920*1080*16bpp*60Hz, intern 1600*768*16bpp*60Hz max backlight 45.9 to 46.2 min backlight (not off), other as above ##### How to turn backlight completely off? Switching to single internal display using Intel tool. External display still connected. 41.0 to 41.5 intern 1600*768*16bpp*60Hz min backlight 47.0 to 47.3 max backlight same as above 44.9 to 45.3 backlight 1 below max, like I normally use it 45.2 to 45.5 32bpp, others same as above 42.0 to 42.3 32bpp, VGA/LAN adapter disconnected, means Ethernet chip truely off This is approx 730 mW difference, impressive. ###### Reconnect VGA/LAN-adapter for double-check, got reproducable result. Unplugging external display only - no change, as expected. The display Acer P235 HL makes a difference between "No cable" and "No signal"! Use Ger&aauml;temanager and deactivate Ethernet "Marvell Yukon ...". Note: This does not deactivate the PCI Express root port, which is done by VGA/LAN-adapter disconnection. 41.9 to 42.3 "Marvell Yukon ..." deactivated. Got same value as with disconnecting VGA/LAN-adapter. Deactivated "... Root Port 1", too, still same reading. OK. Guess is automatically turned down or off. WIRELESS=OFF now to off WWAN (GSM/UMTS). 37.8 to 38.0 WIRELESS=OFF This means another 912 mW less. 37.2 to 37.5 after disconnection of opto-mechanical USB mouse I had connected to right USB port. USB mouse is 137 mW. Assuming 80% efficiency of Mains adapter (and neglecting eff of other switchers) it is 109 mW or 22 mA at 5 V, but it will take less for itself because polling by USB Host at regular interval (##### 1 ms guess) costs power there, and in mouse, too. Energieoptionen CPU="Akku-Lebensdauer" (from "Leistung") does not make any difference. It is only CPU clock if CPU is running, which it is not most of the time here. Anyway "Akku..." is 800 MHz same as CPU braked by temperature. There is a difference between the seconds after last HDD access LED blink and after the "clack" sound of parking heads. It is approx 0.3 to 0.4 mA or 80 mW. Energieoptionen CPU=Leistung again, changed HDD off after 3 min, shortest setting possible, lets see whether WinXP is idle enough to activate it. Looks like I will never get it. 36.5 to 36.7 after 10 min wait, HDD really stopped. Lucky I had hit the moment. Within less than 2 min it started again. HDD rotation takes 0.7 mA Mains. Assuming 70% total efficiency down to 3.3 V powering HDD it needs 112 mW or 34 mA. 25.6 to 25.9 display off after 15 min, HDD running. This is for sure not only backlight, but video refresh and LVDS transmission and display power, too. ######## 24.7 to 25.0 HDD stopped, too. 37.0 change to 45.7 on connection of 27/2 = 13.5 Ohm resistance (metal film 1% ??? red violett black gold) at left USB port, via 8 cm short but thin cables of defective USB hub, voltage at resistors 4.89 V, cable losses unknown, but is safe assumption internally 5.00 V source, VC220 measured 4.99 V without load, resistance by VC220 13.4 Ohm. Means 362 mA at USB, Mains 8.7 mA, 1.81 W at 5 V, 1.9836 W at 228 V, 91.3 % total efficiency. IMPRESSIVE! "Sony STyle Visual Camera" deactivation in Geräte-Manager is difficult to judge. Anyway, that USB/EHCI is used by WIRELESS=ON with WWAN, but no Net connection. It seems to reduce from 38.5 to 37.9, but before fiddling with that setting, while Camera was active, the reading was 37.9 already, did not reduce on deactivation, but increased after activation. Operating Camera by WinXP supplied "Assistent für Scanner und Kameras" increased current from 39.0 to 40.0, but not easy to judge, because often something happend in background. Deactivation of "Atheros A928X..." WLAN brings absolutely no reduction. External 1920*1080*16bpp*60Hz, WIRELESS=ON, WWAN, Connection established but no transfer in progress, Accu charging (at approx 50 %), G.T.Connect running, Eudora open, A.R.10.0.1 open, USB mouse connected, otherwise idle desktop: 71.5 to 72.0 after HDD head parked. #### 70.5 to 71.0 after all except 2 Explorer windows closed, WWAN Connection closed. 69.9 a bit later Long time later, LED still indicating "Charging", current was down to only 40 mA, close to non-charging. (I note in following only the lowest reaging of fluctuations in 0.5 range.) 38.8 one more idle desktop, 2 Wordpad open, WIRELESS=ON WWAN Connection closed, external display 16 bit 33.8 WIRELESS=OFF and waited 2 min for silence, HDD head parked. 38.4 with the Adata 32 GB stick which becomes warm without usage. Using 92% efficiency as computed above, it takes just below 1 W (965 mW) or 193 mA. ##### copy to sticks! 35.7 with hama 32 GB stick instead 27.x with external display off after some idle time, returned to 33.6 after mouse moved.
Author: Harun Scheutzow
Last change: 2011-06-23