Wesley's Tool-Box

The smart meter I installed last month is running nicely, but using it to measure a precise power consumption of an individual appliance is cumbersome as you need to have everything else stable. So it was time for me to invest in a plug-in type electricity monitor. After some comparing, the one from by the company that made the smart meter was deemed most practical. Named SJPM-C16, it cost me about US$18.50 (KRW 22,400) after discounts.

The goal of this sort of electricity monitor is not just about informing you of electricity usage, but also getting you some ideas on how to make savings from such info. Considering this, I liked the way it was packaged. It was pretty compact and minimal, with hardly any waste of space or materials.


Even the manual is a neatly-folded single sheet of paper that lists everything that you need to know when using the product. This includes the fact that South Korea has a bizarre 6-tier exponential residential pricing for the retail electricity, and that this monitor fully accounts for this when calculating the costs. You can also configure for other pricing schemes and the tier prices themselves are also adjustable, making it useful even if there are future changes.

Now armed with this capable tool, I set out to check the power consumption of every appliances and devices scattered throughout the house.

After successfully deploying LED lamps across the FPL lamp fixtures, I thought that the lamps installed in the traditional screw-in sockets should be replaced as well. Ever since these lamps started to go mainstream about 5 years ago, the price kept dropping and the choices kept on growing. This meant that it was a good time to make the move.

Comparing the various offerings on the market, I ultimately settled on the BEAM series of lightbulbs from Sigma LED (formerly Sunsea). They were among the brightest for the rated power, yet priced competitively. Both the 8W and 10W versions cost me about US$3.75 (KRW 4,500) per bulb.


They were set to replace the 20W compact fluorescent (CFL) bulbs made by Hankuk Lighting and installed throughout the house by default. Here is how they compare.


The LED bulbs are shaped closer to the traditional incandescent bulbs, making them thicker and shorter than the CFL ones. Because of the larger diameter, some of the fixtures that were designed only with the CFL in mind may have trouble taking in the 10W ones. This is why I got 8W ones as a fallback.

Meanwhile, the spec comparison reveals a similar trend seen with the longer cousins. The LED bulbs meant to replace the CFL comes in at about half the power consumption and slightly lower total amount of light. I'll be checking if the reality reflects these numbers, of course.

Having a smart meter giving real-time power consumption data provided a lot of insights for my home. The baseline load when everything is idle is about 80W, and the refrigerator running at full power adds 90W to that. So when I noticed that more than 300W were being used during the evening hours even with the TV turned off, I had to track down what the culprit was.

It turned out that the sole reason for this uptick was the lighting. Fluorescent lights in the living room and the study room were turned on for several hours every day and contributing much to the total consumption. Knowing that LED lights were more efficient and that the price has come down a lot recently, I decided to make some major investment.


As with a lot of apartments in Korea, the typical type of lighting installed was PL compact fluorescent lights, or FPL for short. It uses 4-pin 2G11 socket and has external ballast. Lots of replacement methods exist - lamp-only, ballast + lamp (socket is kept), or total replacement. As the lamp-only method is simplest by far and not much more expensive than replacing everything, the choice was obvious for me. I ordered the relevant LED lamps manufactured and sold by TopLux of Korea which were on sale - 23W version cost about KRW 21,000 (US$17.50) and 15W one, KRW 14,000 (US$11.70). Here is how they stack up with the existing FPL lamps.


According to the specifications, the LED lamp consumes about half the power while putting out about 85% of total light, or luminous flux, compared to the similarly sized FPL counterpart. This is indeed quite an increase in efficiency if it delivers. Visually, one side of the lamp is taken up by a long heat sink and uses the same four-pin layout. The pins themselves are simply round, not dimpled in the middle like the FPL it's replacing, so I suppose it won't "hook in" quite as well.

My home isn't particularly wasteful when it comes to electricity spending - it rarely exceeds 200kWh per month except for hot summer months. Still, I wanted to see the real-time usage to make further optimizations. After browsing through myriads of metering solutions, both domestic and abroad, I settled on a particular product sold by Seojun Electric.

Officially called "Smart Power & Charge Meter" model SJPM-B70 (I'll simply refer to it as "smart meter" hereafter), it connects to the main power line going through the primary circuit breaker inside the house. Once installed, it constantly measures and stores the power consumption data. This can then be accessed in real time by a smartphone via Bluetooth technology.


The main thing going for this product is its cost and simplicity. It only costs KRW 42,000 (US$35) online, not much more than the power monitors you plug into an outlet. And you merely need to hook the sensor and the power plug into the right place to get it working - no further maintenance required. Instructions on how to do that are shown with diagrams in the included guide.

You also don't need to sign up for anything as the data stays in your house, fully under your control. As I don't need to have my consumption data shared and analyzed over the internet cloud, this was actually a plus for me. And in case you wanted to show that you have this smart meter installed, the package provides two blue stickers to let you do just that.

Shortly after finishing the battery tests for the earlier post, iPhone 4S and later generations received the iOS 9.1 update. Then the thought crossed my mind that I should have tested the "Low Power Mode" introduced with iOS 9. It's a feature touted as enabling you to use the phone up to an hour more by cutting off some background activities, reduce the screen brightness, and slow down the processor. Would it equally benefit different generations of the iPhones? I ran the GeekBench 3 again to find out.

Here, the only major differentiating factor would be the processor speed because the iPhones were in airplane mode and the screen brightness was manually set to lowest like the previous tests. I did re-run the tests for the 'normal' mode because the iOS version was changed from 9.0.2 to 9.1. And as always, the values are normalized to the designed battery capacity.



This revealed that Apple's claims were not overblown. With the exception of iPhone 4S, the iPhones indeed lasted significantly longer under Low Power Mode: about one and a half hours with 5 and 5S, and about two and a half hours with the Plus phones, which are around 30 to 50% gain. It seems that the processor is clocked down to squeeze out as much battery time as possible. On the other hand, the processor for 4S can't seem to throttle back for this mode, resulting in practically no changes. This means that for 4S, the real-life battery savings would have to come from other tweaks.


And if we measure how much work is done with each mode, it gets more interesting. It confirms that the 4S isn't doing anything different, while iPhone 5 seems to fully trade battery time for speed. Meanwhile, the newer generations are able to do more work under the Low Power Mode. This means that if the tasks you do a lot on your phone isn't impacted too much by this mode, it might not be a bad idea to keep this mode on while you do those things if you want to maximize battery life.