Re-calibrating your iphone's battery meter

My iphone 4 is about 2 years old now and this is the time when battery life is starting to be a bit of an issue for me. Recently, it became necessary for me to use my portable charger on my phone every single day. Now, this is disappointing for me because, as someone really cares about batteries, I do expect a Lithium Polymer pack to last 3 years.

What's wrong with my phone?
I tried my best to make sure that I do not overly drain my battery too much before charging to reduce stress on it. After a while, I realised that my battery meter seems to decrease really fast from 100% but lasts disproportionately longer from 20% and below. This was a sign that the battery meter might be out-of-sync with the battery. Let me explain.

Typically, battery meters on digital devices such as laptops and phones are only estimates. Other than the determinable points such as the "full charged voltage" (100%) and "critically low voltage" (point where phone shuts off), it is very difficult to determine how much charge a lithium-ion/polymer battery has left between those two determinable points. Why? Lithium based batteries often hold their voltage very well until depletion and thus, making it very difficult to obtain a good estimate of the charge level by taking reference from the battery voltage.

As such, battery meters measure the amount of charge going into and out of the battery during charging and usage to estimate the remaining charge in the battery. Over time, the meter can get out of calibration due to random error due to things like difference in temperature, increase in battery resistance due to aging, battery self-discharge, etc.

Honestly, I forgot about battery calibration until I accidentally drained my phone battery till it shut off as I did not have access to a wall socket for 2 full days.

I was on the bus and minutes away from the safe refugee of my charger before the my phone decided that it was enough and shut off on its own at 2%.

How to recalibrate your battery meter:
I took the chance to recalibrate the meter by simply leaving it to charge for about 2.5 hours without unplugging it or using it. I purposely left it plugged in longer than I know it takes to obtain a full charge because I had to ensure that the battery had really reached its "full voltage". Remember, your battery meter may not be accurate even though it shows a 100%. However, the charging electronics will be able to tell if it has reached full charge and terminate charging.

After that, my phone was able to last 1 full day without charging compared to half day. Not bad considering that the battery had spent 2/3 of its expected lifespan.

Afterthoughts:
IT equipment has become so advanced to the point where everything is so convenient to the user. Gone were the days when instruction manuals were thick and explained the workings of certain user-maintainable components. Manufacturers expect their products to work perfectly for the user without the hassle of having him/her learn how to use it, which is why everything is so simplified and obscure to the user.

You may have encountered cameras with simplistic bar battery meters which deplete very quickly after losing the 1st bar. This type of battery meter attempts to use battery voltage as a reference, but is pretty much useless because it is rather drastic. Below is an approximation of the battery charge compared to typical battery indicator icons.

Well, I hope this article helps you understand a little better about your battery life and battery meters. Hopefully, this will minimize your encounter with the dreaded low-battery warning. Cheers!

Taking public transport in Singapore as a tourist (and going to Night Safari/Zoo)

I noticed a lot of international visitors at my blog. If you happen to visit my country, Singapore, and plan to head to the Night Safari (just the zoo, but at night), I'll have you know that the easiest way to get there is...

1) Go to Ang Mo Kio Bus Interchange. It is connected to Ang Mo Kio MRT (train station).

2) Take bus service no. 138. It is at the last boarding berth so you'll have to walk the entire length of the Bus Interchange.

3) To pay for the ticket, you either get yourself an Ez-Link card (a contactless stored value card) from a TransitLink counter at either an MRT or Bus Interchange or you can pay in coins when you board the bus.

-When paying in coins, you have to tell the driver your destination and he will tell you how much it costs.

-When using Ez-link card, tap your card when you board and tap again when you exit. The fare deducted will be the based on the distance you travel.

4) When in the bus, you will start to find that the surroundings are a little less built up compared to town areas. At a certain stretch, the bus will drive through a rather quiet road surrounded by trees. At this time you'll probably start asking other passengers where the Zoo is. Honestly, it is difficult to tell you the number of stops to go as we don't keep track ourselves. Don't worry, the Zoo is the bus' last stop before it loops back to Ang Mo Kio Bus Interchange. The driver will chase you out of the bus even if you don't alight.

5) Enjoy yourself!

6) As 138 is a loop service, the bus stop you alighted at is the same bus stop to board at to go back to Ang Mo Kio Bus Interchange.

I wrote this because I get asked many times on my way home and I see many visitors becoming worried once the landscape turns darker and quieter as the bus makes its way to the Zoo

Hint, there are several 24hour eateries along the 138 route and if you are feeling hungry after your visit to the zoo, just alight anywhere along the row of shophouses.

Fluorescent vs LED: Is it worth the switch?

When you head to the shops to get new bulbs, you get confronted by energy savings claims for choosing particular bulbs over "traditional" incandescent ones. While it is true that fluorescent and LED bulbs are both several times more efficient than incandescent ones, chances are, you are unlikely to be using incandescent bulbs in your house.

Most people are already using fluorescent lamps, be it the tubular kind or the compact swirl type (Compact Fluorescent Lamp). These offer a big jump in energy efficiency when compared to incandescent lamps. The price too, is a big jump. In the recent years, LED, a newer option appeared in the market as the prices became within the reach of the average consumer. These are often touted as lifetime bulbs as their lifespan is so long that most products that use LEDs are not designed for bulb replacement.

While it is true that each type of lamp have different colours, advantages, lifespan and brightness, it is important to consider how much benefit they offer against the other types.

Colour

Incandescent: In terms of colour spectrum production, Incandescent offer the best colour rendition because it provides a smooth spectrum of colours, just like our sun. This is why they are often used for photography, mood lighting and shop displays.

Fluorescent and LEDs: These are often criticized for their "coldness" and "harshness" of the light quality. Colours of things do not look "right" under these lights because they produce discrete colours instead of a smooth spectrum. This is due to the way they produce light from the excitation and relaxation of electrons. There are Fluorescent and LEDs that offer better rendition, however, those will cost more.

Lifespan

Incandescent: The worst of the worst. The fragile filament is rated in the range of 1000hours. (~7 months of use)

Fluorescent: Fragile design, but still lasts 10,000 hours (~5.5years of use) depending on the model, which is awesome. They become dimmer as they approach their end-of-life. The lifespan is also dependent on how often they are switched on and off.

LEDs: Hardy design. No breakable parts. 20,000hours (~11 years of use)

Brightness/Efficiency/Price

For the same application and similar brightness level, the power needed for each bulb are -

Incandescent: ~70W / $3 (Halogen E27)
Fluorescent: ~20W (CFL $12.90)
LED: ~8W ($14.90)

Prices from IKEA.SG

Notable things
Numbers are not all that matters

Dimming capability: Incandescent bulbs are completely capable of dimming while Fluorescent and LEDs are not always dimmable and they tend to be more expensive if they are capable of dimming. Incandescent bulbs are extremely versatile for this aspect because of their simplicity. Producing light by heating something up is simple!

Components: Most incandescent bulbs can be plugged in directly to the mains without requiring any other circuitry. Fluorescent bulbs need a ballast and a starter, while household LED bulbs have a step-down and regulation circuitry. These can also fail in time to come.

Cost Benefit Analysis
While it is clear enough while incandescent bulbs are really cheap to buy, they cost a lot more to operate in the long run. Hence, I will not be comparing incandescent bulbs.

Do LEDs really better value for money in the long run? To answer this, lets do a life-cycle cost analysis!
Take 20,000hours of operation (If switched on for 5h per day, this works out to be ~11 years of usage)

Fluorescent:
2 bulbs needed = 2 x $12.90 = $25.80
Energy consumed = 20W x 20,000h x 25.95c/KWh (Singapore electricity tariff) = $103.80
Total cost after 20,000h = $129.60

LED:
1 bulb needed = $14.90
Energy consumed = 8W x 20,000h x 25.95c/KWh = $41.52
Total cost after 20,000h = $56.42

Savings over Fluorescent = $73 (a 64% savings)

Conclusion

Initially, I was skeptical that LED are any better than fluorescent in terms of cost effectiveness. After doing a simple life-cycle cost analysis, it turns out that using LED will cost less than half the cost of using fluorescent in the long run. Sure, there are many different manufacturers and the price differs wildly. High end bulbs costs a lot more than the bulbs used here for comparison and they offer a lot higher efficiency while producing high brightness. If they are optimally placed, they may be able to replace 2 less-efficient fluorescent bulbs, thus reducing the number of bulbs needed in a home.

Bought another torchlight - the Nite Ize Buglit

While the haze was about, I took shelter in a shopping centre while waiting for my friend and I chanced upon some lights in Home-Fix. Frankly, I get the feeling that DIY products sold in an air-conditioned are often marked up in price and the only reason I was in the shop was only to window shop. It is particularly enjoyable to look and feel products from air-conditioned shops but they ain't the best place to buy stuff from since they probably charge you for the air-conditioner in their products.

Brand Intro
It was then I chanced upon a little keychain light from Nite Ize. It a US brand that seems to have a few basic products and a lot of other products that revolve around it. One of their basic product is the Inova Microlight, which is a simple 5mm keychain light. The same keychain light is then incorporated with several other add-on products that add value to the light that they have. By doing so, it makes it easier for mass production because their basic product is essentially the same for their entire product range.

 Its a bug!

Size comparison

Left: Photon microlight, Middle: Nite Ize microlight by itself and the bug legs. (If you don't fancy the bug legs, you can also get the microlight by itself)

The mini-clip and flexible legs are also sold on its own if you wish to purchase more.

The Buglit Microlight
This is the little light that caught my eye. It is a perfect replacement for my decade old Photon microlight which was mysteriously damaged when I put my keychain bunch into my bicycle saddle bag. I was really disappointed because it is very well thought out and in my opinion, the best keychain light.

What I look out for in a keychain light
1. Firstly, it has to be extremely convenient to carry around. Being a torch light enthusiast, you can have many expensive and advanced torch lights lying around at home. But, normally, no one carries their torchlights around most of the time. As the old adage goes "the best camera you have is the one that is with you when the need arises" and it is the same for torchlights.

2. Made of durable plastic. Why plastic? When something is hung on the same keyring as keys, they are bound to be scratched by keys. Some metal keychain lights have to go to great extent to be anadoized, galvanized, etc. just to be hardy enough to be used alongside keys. What's the point of that when plastic is hardy enough and soft enough to withstand hard objects?

3. I hate it when keychain lights needs to be continuously pressed in order to keep it on. That effectively means that you'll have to reserve one hand just for the torch. I need one that switches on after 1 click.

4. Auto-off feature: keychain lights are bound to be turned on accidentally one time or another. Having an auto-off feature saves the battery from running down and saves you from the nasty surprise of having a dead battery when you need a light the most. (Most keychain lights do not have this feature. The Photon microlight has this and it is why I regard it as the best keychain light).

5. Run on reliable and common lithium coin cell batteries. Lithium coin cells are meant to be reliable for 10 years and more, unlike alkaline coin cells that have lower capacity and will drain away in less than 5 years. (Most scientific calculators use the old LR44 alkaline coin batteries.)

Why I bought the buglit
Although the buglit doesn't have an auto-off feature (I haven't test it yet. Nothing was said about this on in the product description), what the buglit offers in return is the weird flexible legs that serves the dual purpose of protecting the switch from accidental activations

EDIT: After leaving it on for more than 10mins, it did not shut off and I can safely say that it does not have any auto-off feature.

The button is in the middle for both microlights. The Photon on the right has 2 buttons: 1 for contant on (to scroll through different modes) and the other for momentary on, which is rather clever.

Strobe mode for extra visibility. Can possibly double up as a front blinker for bicycles in a pinch. =)

 The run time and output intensity doesn't seem to be proportional. HIGH is 6x brighter than the LOW, but the runtime is only about half of LOW. This is because of the way ANSI standard calculates runtime. This light is probably not regulated, which means the light output drops as the batteries drain. The mircolight will spend most of the 10hours near or below 1 Lumen in HIGH mode (I.e. 6 lumens to 0.6 lumens) .

"The continuous time lapsed from the initial light output to when the light output is at 10% of the initial light output." -ANSI definition

Practically, this lamp will operate at 6 lumens at the beginning of the battery life and slowly dim down till 0.6 lumen for the first 10hours. But this is okay as this is enough for indoor use, close-up work and getting you to your big ass torch lights. I prefer keychain lights to be non-regulated because this means they can run for a lot longer than regulated lights. In an emergency, its better to have a dim light than no light at all.

 

 It uses 2x 2016 lithium coin batteries, which is incidentally the size of 1x 2032 battery.

 You can use 1x 2032 battery instead of 2x 2016 batteries in this. The brightness will be reduced but the run time will be doubled. I like this "coincidental" feature because I bought lots of 2032 batteries from dealextreme a few years ago. I have several lights that uses 2032 and I hope to standardize the batteries.

The flexible "bug legs" offer a creative way to go hands-free. This greatly ups the versatility of the light. In fact, all lights should have this feature!

In all, if this light is available in your area, do get one! Everyone should have a reliable keychain light to prepare for the occasional. It is reasonably priced too.

Eneloop glitters!

Got these 4 AA eneloop glitters for my birthday present. These little things have been regarded by most forumers at Candlepowerforums as the best rechargable NiMH batteries in the market and it is hard not to see why.

 

Self Discharge

These little things have impressively low self discharge. Self discharge was a problem with rechargeable batteries in its early days because it gave rechargeable batteries a bad reputation of being dead every time you need it. Couple that with the slow overnight chargers of the yesteryear, users of rechargeable batteries needed to be extra thoughtful when planning to use their batteries for whatever purpose. Most batteries would be flat by the end of 2-3 weeks and needed to be charged again. Then came the infamous high capacity Sanyo 2500mAh I bought about a decade ago which had the ability to lose almost all its charge in less than half a week. That was a turning point in battery history where people started to doubt the usefulness of trading self-discharge for higher capacity. After that, Sanyo started making eneloops, the first low self discharge batteries with albeit lower capacity of 2000mAh.

The low self discharge feature, for the first time, made consumer rechargeable batteries reliable.

No. of Cycles

It turned out that the benefits of changing the battery internal structure for low self discharge also rewarded the battery with longer longevity. Unlike normal rechargeables, low self discharge batteries tend to be rated for a higher number of recharge cycles. My glitters are rated at 1500 recharges while the latest eneloops are rated at 1800 recharges. Even though mine are the older version, they will still last way beyond normal NiMH batteries that are often rated for 500 recharges.

Performance

Wait a minute, there should be a catch in here somewhere. Does it perform worse than normal rechargeables? It turns out that they don't. In fact, they are the most recommended batteries for high powered torchlights.

Price

With such features performing way beyond most batteries in the market, one would expect that these eneloops to be rather expensive, but surprise! They are not. In Singapore, 1 AA or AAA goes about $5 to $6, which is about the same price as other brands.

I normally don't go for consumables that come in a pretty package because that is like buying a more expensive a nice printer cartridge not for increased ink capacity, but rather for its looks. But for well designed products like these, I'm going to make an exception. I may just get more of it to complete the collection. Heh.

My new 2xAA Batteries Emergency Charger for iPhone 4 / 4S/iPod - Black from dealextreme!

Hey everyone! I've finally received my new iphone portable charger from dealextreme. Its SKU67065 from dealextreme.com. I bought it for US$5.30, which is a reasonable price considering that most brand-less li-polymer mobile chargers go for about SGD$10.

I bought this because my dad's old hand-me-down li-polymer based portable charger isn't really working out for long trips away from the power socket. Sure, it does help to ensure I'll survive the rest of my day but that would mean I will have to be conscious about the battery usage.

The biggest difference between this and my old portable mobile charger is that I can always replace fresh batteries to charge my phone so that as long as I have enough batteries with me, I can always keep my phone juiced up all the time. Using rechargeable NiMH batteries to power this little thing provides a guilt free environmentally friendly way to keep a smartphone happy for hours. This is unlike energizer's energizer's aa portable phone charger which was reputed to be only good when used with expensive lithium batteries.

I particularly like the clean design of this portable charger. There are no switches, buttons whatsoever. All you need to do is to insert them batteries and plug it into your phone. Viola! It starts charging instantly. Due to this simplistic design, it is feasible to leave your batteries inside all the time without the circuitry slowly draining the battery away (refer to parasitic drain below). 

The finishing of this charger is also quite high quality. The plastic is tough and durable. Something that I expect to last quite some time.

 

Simply slide to unlock.

I used lithium batteries and it worked too.

The size and design complements the clean iphone look and is not at all obstructive when I used the phone when charging.

The bottom part of the charger follows the contours of the iphone so that it can be rested on a flat surface. This is good as it is unlikely to bend the connectors in the long term.

So far, I tried two different NiMh batteries:

MAHA imedion 2400mAh  - 60% increase (avg).
IKEA 2000mAh NiMH - 50% increase (avg)

Parasitic drain (not plugged in): 0.4mA
[Theoretically, a pair of MAHA imedions would be completely drained after being left inside for 8 months]

The charging data is pretty consistent given the delta in battery capacity and phone charge increase. I am also particularly pleased that this little thing produces very little heat in the process of charging, translating to minimal energy loss.

I would recommend using Low Self Discharge (LSD) NiMH batteries for your charger to give you the assurance that there will still be energy left in the batteries when you really need them. Typical NiMH batteries will lose most of its energy by around 3 weeks while LSD batteries can retain as much as 70% over a year or two.

All in all, an excellent buy with a very reasonable price considering the build quality and efficiency of the circuitry.

Is it okay to mix old and new batteries?

Most batteries would come with the same standard advice in full caps DO NOT MIX NEW AND OLD BATTERIES. Now, we all know that mixing new and old batteries will mean that the old battery will be the first to go, dragging down the performance of the entire group of batteries hence, we mixing is a bad idea. But is it really a bad idea all the time?

But wait. Why would you want to mix old batteries with new ones anyway? Chances are, some batteries are "half used" and it is difficult to say which ones should be thrown away. This is especially so for "drained" batteries that were used in digital cameras. These batteries often have enough remaining capacity to serve low powered devices such as remote controls, sensor lights and calculators for a very long time.

If you have a at least cheapo multimeter, you would be able to find out the voltage of the battery. Although this is not exactly a scientific way to tell the remaining capacity of your battery, it at least give a very rough estimate about when you should actually throw the battery away.

A typical AA/AAA battery should read 1.5V without load. Without load means the battery is not being used at the moment. Normally, the voltage reading of a battery will sag if it is being used. This is more prominent under more demanding loads.

Ok, if you want to mix batteries, read on. But be reminded that this advice is only applicable to non-rechargeable batteries! Mixing full and near-empty rechargeable batteries will certainly damage the near-empty ones as they go beyond empty.

1st step: Check the voltage under no load!
- Put the voltmeter to read "DC voltage"
- Touch the terminals with the probes.
- Is it between 1-1.5V? If it is, re-use it for less demanding devices!

 Information is key...

Step 2:

- Mix those batteries!

Step 3:

When the device is once again low on power, re-check those batteries and see which ones are low. I found that for a 3-battery device, usually only 1 battery is completely dead and needs replacing. Once that dead battery is replaced, it works well again! By doing this, I saved many batteries while keeping my sensor light bright and nice.

Why oh why manufacturers make devices that uses odd number of batteries?

Disclaimer: Alkaline and carbon zinc batteries may leak after a while, regardless of whether they are empty or not. However, driving them till empty increases the chance of leakage, which is corrosive to metal contacts. Do check your battery powered devices once in a while.

I discourage the use of non-rechargeable batteries because they are extremely low on value since they only work once. Rechargeable batteries are slightly more expensive, lasts at least 500 cycles and the electricity used to recharge them is negligible compared to the price of new non-rechargeable batteries. However, they can be rather cheap when bought it bulk for devices that you don't want to keep on an eye on, such as remote controls. These low powered devices have the capability to operate even at very low voltages. This means that you'll have no clue that the battery is almost dead. Rechargeable batteries should never be brought below too low a voltage as it will damage them.

NUS attempts conversion of petrol powered motorcycles to electric.

http://usp.nus.edu.sg/whats-new/2013/usp-launch-demo-electric-bike.html

A bunch of USP students managed to convert an old petrol powered bike into electric propulsion.

The main point of this seems to be aimed at extending the life of really old motorcycles with failing engines. Given the small capacity of most motorcycles, these bikes are usually ridden hard in Singapore in order to keep up with the pace of the roads and expressways. Particularly bikes under the 2B category.

The new electric propulsion makes use of seal-lead acid batteries which are typically very heavy while carrying little capacity, takes a hell of a long time to charge and its lifespan will be shortened every time the battery is used near its full capacity. On the flip side, they are relatively cheap to buy and cheap to maintain.

The only problem this project has is that the costs:

"...costs for the average motorcycle rider using the converted electric engine would drop from about S$121.11 to S$29.79 per month"

The estimate of $121.11/month is overly high if they are only considering petrol costs of a typical 200cc motorbike. Although the chassis used in this project is probably one that came with a 400cc engine, I sincerely doubt that the new electric motor has the same performance as a 400cc engine. Hence, it is fairer to compare it with a petrol engine of similar performance, which will be one that is 200cc and below. Unfortunately, the petrol costs for engines this small typically achieves very high fuel efficiency of about 30-40km/l, which means that it will cost about $70 per month if it is used for 38.5km per day. This means a saving of only $40 per month with the additional inconvenience of range anxiety, inability to follow the pace of other vehicles on the road and the initial conversion price of $3500 is already enough to buy a used bike with about 3-5years COE left.

In terms of overall running costs, an electric bike will save on maintenance fees that a petrol powered bike has to go through every 3 months, however, it is important to note that when the batteries are at its end of life, the replacement will cost quite a bit. In the end, it is difficult to tell which one will cost more in the long run.

While this project demonstrates the feasibility of converting the an old petrol bike into an electric one, the economic feasibility of this endeavor is not good because of the other costs of owning such a motorbike in the first place. This includes insurance, the need to renew the COE of the old bike and road taxes. All these additional fees make it hard for anyone to consider having an electric bike especially when the owner gets charged the same disincentives as one who owns a traditional motorcycle.

Solar power now: The Ikea Sunnan lamp

Yes, I've been a bit of an Ikea fan recently. It is kinda nice to be immersed in new furniture, decorative stuff and lights from Ikea because there is such a huge variety! Makes me wanna buy a house and fill it with interesting and functional products and furniture. I think the thing that makes me want to visit Ikea time and time again is because their products range caters to those with deep pockets to customers who are struggling with the high cost of living in Singapore. Naturally, the cheaper products are not always very well high quality, but they can be rather cheap. Some of the time, the cheapness really comes from how the product is designed and packaged. One example was a table lamp I saw which was on sale for $5.90. What the hell, it is cheaper than a Big Mac meal! Oh my oh my, it was tough to resist picking up every little interesting product I saw.

I wanted a small directional lamp for my table so that I can light up my table. My ceiling lights are really bright and it is kind of wasteful to light up my entire room when I'm only at my table. So, I looked at several of their flexible-neck lamps that uses LEDs. Damn, it turned out that most of them produces a far amount of heat. I suspect that the entire step-down transformer is housed in the head of the lamp since LEDs do not produce much heat. Moreover it was quite a let down since they were not as bright as my torchlight it was producing more heat than my torchlight!

So, I came across this small work lamp that uses a solar and rechargeable batteries, the Sunnan lamp. It too has a flexi-neck. Most of the time, solar based products are rubbish - the entire product becomes useless when the rechargable batteries die. Not this one though. The design allows you to swap dying batteries.

Whats more, the designers figured that it would be strange to put the entire lamp in the sun to charge, so they made a removable module with the solar panel and batteries in it so that it can be sufficiently charged in the sun.  The only problem is that the batteries will get pretty warm when left under the sun. This will potentially shorten the lifespan of the batteries. Currently, I'm thinking lengthening the wires to the solar panel so that I can place it outside my window permanently to let it charge my batteries rather than having to remove the module every time.

The lamp is rated at 20,000hours so I probably won't ever have to change it. Even if I do, it is to upgrade it to a newer, more efficient bulb in the future. The batteries however, will probably need to be changed every 1.5years. I'm not sure how long the solar panel will last though.The circuity is also very simple, if anything fails, it is possible to run to sim lim tower to get a replacement.

I don't think it can replace a normal lamp if you are intending to use it to light up a table for writing an essay. But increasingly, we are using solely using laptops for work and play and this lamp is sufficient for lighting up the keyboard and for doing simple stuff. I can imagine using this for lighting up outdoor tasks such as BBQing.

Edit:

I tried charging the battery pack a few times and it worked splendidly. The solar panels may take quite a while to charge up the battery but it does get the job done. Simplicity is good.

The solar module opened up to reveal the outdated BYD brand 3x 1200mAh NiMh batteries. I really doubt the batteries can take the abuse from being heated up under the sun. The really simple circuit board holds a diode and a fuse. I'm not sure if a fuse is so necessary but it will probably prevent a short circuit should a careless person touch both leads together. The diode is to prevent blackflow of current into the solar panel. Thoughful and simple.

When it comes to electrical components, the less there are, the more efficient the entire product is. The lean circuitry of this lamp does without many other components that it can live without. Thing such as:

1) a voltage regulator to maintain the brightness of the lamp throughout the entire battery capacity.

2) Overcharge protection to prevent stuffing too much sun energy into the batteries. After all, the battery module is likely to be unattended when left outside to the sun.

What I would recommend is to check the individual voltages of the batteries once in a while for uneven charging. If any uneven voltage is spotted, charge them up on a charger that charges each cell individually (most chargers do that already). This will minimize the chance of over draining a single cell and damaging it in the process.

Project: An automatic drawer light

Now, I could have simply used an automatic DIODER drawer light to light up my little drawer. But I didn't like it that it switches on only for a short 12 seconds. I want it to stay lighted up as long as the drawer is open. So, I thought that it might be better to make my own. It shouldn't be too difficult right?

My ingredients are:
White LED strip
A reed switch
8x AA batteries and holder.
Some black sticky tape to match my table.

I bought a 10m white LED strip from dealextreme. It was quite a good deal considering that they are $15 per meter if bought locally. These were really bright! It is bright enough to be my night light and it can be really discrete since they are so thin!

This is my little power source. My LED strip is more for automotive use and takes in 12v. So, 8x 1.5V AA batteries are required. I measured the power consumption and found that it would take 13hours to fully drain these batteries. I could use rechargeable batteries to save cost in the long run but I also risk damaging my rechargeable batteries should I run them down completely. The circuit is simple and hence, there is no protection circuit. These cheap and cheerful IKEA alkaline batteries cost $2.50 for a pack of 10. They are not as good as other branded alkaline batteries, but these are really value for money.


This is my hidden "normally closed" reed switch hidden under the sliding tray of my drawer. The other piece is stuck to the drawer door where the two parts will be separated when I open the drawer which then closes the circuit :)


The LEDs and their wires are hidden from plain view using black tape. See how bright my drawer is compared to the rest of my room? Having bright light shining on my drawer makes it easier to take things from it.

Alternative transportation: Cycling to work in Singapore

Last Friday, I decided to cycle to work. It took me a while to get to do it because my dad has always been driving me to work since it is on the way. I like the idea of reducing cost and redundancy, hence this logic made it difficult to get me off the passenger seat and onto my saddle. After all, why not hitch a ride when my its on the way?

The distance:
My office is 7km away from my house

The car/private transport:
Takes an unbeatable 15-20min for me to reach my workplace even in bad traffic. Clearly the ultimate choice of transport for anyone who can afford it right now.

Public transport:
Having such a short distance means that if I take public transport, waiting for the bus can take up a significant portion of my time since the actual "moving" time is actually quite short. In addition, the bus doesn't bring me directly to my office and I would still have to walk another 400m~ to my workplace. This brings up a total traveling time of about 30mins.Overall, quite an acceptable time for a daily commute but there is very little comfort in taking public transport during peak hours. These buses are often packed to the brim due to all the people rushing home from their workplace all at the same time. What really got on my nerves was that the road was rather clear but the buses were infrequent and mostly packed. So, I thought, why not get on the road myself?

Bicycle:
I have been cycling on the roads since I was secondary school and by now, I'm quite comfortable with vehicles speeding past me at close range. Possessing both motorcycle and car licences allows me to know the proper road etiquette. In addition, having driven for 5 years now, I have enough experience to preempt the moves of other motorists. Before I type and type about the benefits of cycling, I must admit that it won't be easy for any casual cyclist to pick up their bicycle and start cycling to work. It is important to first be acquainted with the roads. First try during off-peak hours and preferably with someone who is experienced with cycling on the road. I started off cycling on the road on my own and I was scared stiff during my first few tries.

Before I rode off to my office, I prepared several things:
1) Rear blinkers for better visability in the morning,
2) polo tee and jeans for my dress down day,
3) a small towel and a small bottle of hair/body soap.
4) a lock
and I was wearing dry-fit shirt and pants for the ride.

This wasn't a relaxed ride for me. I was trying it out as an alternative transport to bus and this was supposed to be comparable to public transport for it to be feasible for me to consider doing this on a daily basis. I have transport allowance so it did not make sense for me to use private transport unless there is something else I can gain to compensate for not using public transport. To me, I want to incorporate some exercise into my lifestyle as I am far too lazy to head to a gym or schedule some time for a run. Hence, cycling to work is my best option to provide me some exercise and transport.

Trying to keep up with cars and cycling at a speed that doesn't end up slowing down other vehicles really take quite some effort. By the time I reached office, I was so tired!

I took a quick 5min shower and I was at my desk. I made the mistake of not airing my cycling attire on my bike so that I could re-use it on the way back. This meant that I had to cycle with polo tee and jeans but it wasn't so bad as the evening was rather cooling and I did not bother to cycle as fast as in the morning.

So, if you are comfortable with cycling on the road, I urge you to give cycling

Thoughts on Intelligent Furniture

The idea of having intelligent furniture is very appealing. When someone talks about a "smart" home, it is easy to imagine a home that has many of its electrical appliances wired up to a computer which controls and monitors everything. I have seen commercials of some sort depicting automated security, lighting, water heater and even the TV many years ago. But the trend never really caught on. Some of these features were just too extravagant and just unnecessary. Several years ago, adding automation to your home will probably cost more than hiring a maid to do those tasks for you. Now, with increasing maid levy and the increasing ease of programming (I don't know how but I think I should learn about it someday) simple applications for mobile phones, it is now easier to be a lazy person, but only if you are hardworking enough to wire everything up in the first place.

Last year, a Singaporean from UC Berkeley automated his room and this is the result:

Meet BRAD (Berkeley Ridiculously Automated Dorm): http://lab.dereklow.co/brad/

From his website, he talks about the stuff that is used. Most of the things are easily bought from DIY shops, online DIY shops of course. DIY shops in shopping centres are ridiculously expensive and the cheap neighbourhood ones are hard to find because they are usually run by the older generation.

I don't think I'll need a party mode in my room but I do like several of the design features he used for BRAD. I particularly liked the way the lights are positioned. As a dorm room, everything is designed to be as minimalistic and efficiently, and so, the lights only light up the areas that need them, thus reducing the amount of electricity needed and also to make it less disturbing to your roommate when you are mugging way into the night. This makes the room very sleek, just like a well thought out hotel room. Secondly, I like the way motion sensors are used so you don't have to trouble yourself to walk to the switch to turn off/on the lights.

However, over-automating your room can be quite an annoyance at times when the automation does things at times you don't need. A friend of mine stayed a night at MBS and told me about annoying experience of having all the lights, curtain opened and the radio turned on when her roommate came into the room at 3am in the morning. Apparently, these things are programmed to welcome the guest when the door is opened by the keycard.

Time for another lighting project!

So, I don't want my room to be too smart for its own good. I just need it to give me purpose-built lighting. My current room lights follows the popular strategy of flooding the area with as much light as possible while using the least number of bulbs and fixtures.It does the job well, but it lacks sophistication. I don't want to turn on so many lights just for a simple task.

When I am at my desk, I only really need lights for my desk area. By doing so, I can decrease my electricity usage even lower through better placement of my lights. Currently, I am using CFLs for my room light, which is already quite efficient. So, I have to make sure that I do not end up using more electricity with my replacement lights.

For that extra bling, I will also add lights to my drawers. To add a touch of sophistication, I will be using magnetic switches which will turn on my lights as I open the drawers.

The table I'm using is ikea's MALM desk. It is a clean and simple table with 1 slide-out drawer and a lower cabinet with a swing door. I like the fact that it is simple, but it is by no means elegant. There is nothing that really stands out about this desk.

 

So boring hor... (picture from ikea)

And so, I want to give it some smarts by wiring some LED lights to it. Before I bought anything, I took my trusty dioder drawer light and placed it at several positions to see which position gives me the best lighting for my drawers.

Top drawer: It turns out that the best position to place the LED strip is on the edge of the table, shining down on the drawer rather than at the edge of the drawer. This allows the LEDs to be placed higher and shining evenly onto my things! Unfortunately, this means that I'll have to modifiy the sensor of my dioder strip and I didn't have the heart to mod such an expensive and well made LED strip. It is like modding a ferrari. Any mod you do to it probably makes it worse because the people who made it really knew their stuff.

Lower drawer: Best to place at the top edge of the swing door. The drawer is actually very deep and it is very difficult to see anything even if I were to light up the inside of the drawer. So, to make more efficient use of my deep drawers, I went to buy these boxes to keep things organised. I keep the things which I need most frequently on the outer side for more convenience. For example, my printing paper is on this tray below which I can easily take out. With the LEDs pointing towards the floor, I can see my things really clearly :) yay!

But, I don't intend to buy another 2 ikea dioder strips with sensors because they are really expensive! 2 of these will set you back $60! Instead, I ordered the components online and I'll fix them up myself to save cost. I'm a young and poor person who just joined the workforce, you know?

Another sensor light: the IKEA Komplement sensor LED strip

Yes, this is yet another write up about sensor lights. I like how sensor-based lights work because of how convenient it is. Having a sensor of sorts allow the pairing of switching on of lights with other actions, such as opening of a wardrobe door. And since I have two sides to my wardrobe, I decided to try out a different sensor light since I was a little disappointed with my Dioder drawer light due to the fact that it only turns on for 15s when the sensor is tripped. I needed something that stays on when my wardrobe door remains open. 15s is way to short for arranging clothes or simply picking out what I want to wear to work.

So, here comes the IKEA Komplement LED strip. I bought the 42cm model for $59.90. This is way longer than the 29cm IKEA Dioder drawer light. Unlike the Dioder drawer light, the Komplement stays on when there is no obstruction in front of the sensor. It uses power from the mains so there is no need to change batteries whatsoever. Hurray! I finally found what I wanted!

But no, it isn't really what I wanted. There are two problems - energy efficiency and ugly cabling. Firstly, the cables are wriggly and it is difficult to line it neatly. This is one problem that is completely mitigated by battery powered devices. It cannot beat the elegance of the Dioder drawer light.

Secondly, and more importantly the energy efficiency - LEDs are meant to be super efficient as they convert a very high percentage of electrical energy into light rather than heat. This is the concept I want to adopt for my room. I want my room to be smart, neat and most of all, energy efficient. Unfortunately, the IKEA Komplement does not really follow through the idea of energy efficiency for the Komplement. This is probably because it is powered by the mains and do not have the same constraints as a battery powered light. I felt disappointed about this partly because I wanted to power this up with a rechargeable battery pack to get rid of the messy looking cables.

Specifically, the things that let this light down are the transformer and the sensor. When the mains are left on and the light deactivated, the transformer still remains (very) slightly warm to the touch and this is bad because considering how little power the sensor takes. This means that the transformer is not very efficient. For the record, I did not measure the power consumption from the mains. It would give a much clearer picture of the intake power to know this and it would be possible to calculate how much it will cost to leave it plugged.

Although I mentioned that the sensor takes in only a little power, the sensor alone (without the light powered on) can drain a pack of 8x AA batteries in about 8days. Compare this to the 6.25months for 6x AAA for the Dioder and it becomes clear how much more parasitic the sensor is. This makes it very impractical for me to use batteries for the Komplement.

Power usage (mW)	Dioder drawer (29cm)	Komplement LED (42cm)
Residual	1.74	120
Activated	783	1440
Sensor/LED %	0.22%	9.09%

I've measured the power usage of both products and I found that for the Komplement, the sensor takes in a whopping 9% of the LEDs power consumption when the light is deactivated, which is why it will drain my battery pack so much quicker than the Dioder drawer. It is quite ironic that LEDs are now so efficient that it makes other components such as transformers and sensor modules look really bad in terms of energy consumption.

Instead of using the sensor to activate and deactivate the light, I am now using it more of a night light. It is easy for me to switch it on and off as the power socket is quite near my bed and it is not too bright to cause discomfort when switching it on at night. Overall, it works the way it should. It will definitely satisfy anyone looking for a quality drawer light. However, I don't like the fact that they did not carry the idea of energy efficiency all the way.

 

My drawer! Now, let there be LED lights!

 Nice warm soothing light from 24 LEDs

 

The sensor is in the middle of the light. It senses frosted glass perfectly well. (Top: Off when it senses nearby object. Bottom: Switches on when doors clear the sensor area)

 Well, yes it has a switch that bypasses the sensor :) But note that the transformer still takes in energy even in OFF.

The small transformer. Judging by the specs and assuming that the max intake (16w) will give the max possible output (6w), the transformer has a conversion efficiency of 37.5% at max load. As far as I know, transformers are generally inefficient at really low loads and becomes better as it reaches middle to max output. Even when the light is on, the load is only 24% of the max permitted load. Chances are, the efficiency never really reaches its peak. Having that said, packaging a higher quality transformer equates to higher price. I'm guessing that they use the same transformer for all their LED lighting range to achieve economy of scale at the cost of higher efficiency.

 Wriggly cabling. Made worse by using sticky tape.

 Komplement's sensor light as seen from a camera. This is a lot brighter than the Dioder's sensor IR light, probably a contributing factor to the sensor's power consumption. On the flip side, the sensor range is a lot further than the Dioder.

 Dim IR sensor light from the Dioder. It may be dim but it works just fine.

It also has a physical switch between the mains and transformer. It makes good sense to have the switch at that position of the circuit because it cuts off all power to the transformer.

Edit: I tried to remove all the wire clutter by powering the Komplement with using a 3x 18650 li-ion battery pack. The 3 batteries total up to around 12v which is a perfect replacement for the included transformer. Sadly, the batteries will drain out by 4-5 days of minimal use due to the fact that it needs a constant stream of electrical current. I know that my batteries are 2000mAh, so at 10mA, the Komplement will drain my batteries within 8 days. This is way too inconvenient. On the other hand, my Dioder with a sensor lasts more than a month without any problems.

 

These cells were salvaged from my gf's old laptop battery pack. The sticky tape on it is to stick on the protection circuit.