Apple Iphone Charger efficiency test!

I've bought my electrical meter for quite some time now and have been testing the power consumption of various appliances in my house.

One of my more prominent device is my Apple Iphone charger. It is a rather mysterious gadget because there is very little technical specifications about it other than the fact that it outputs up to 1A @ 5v.

Some did a tear down review of the little charger and concluded that it is actually very well designed compared to a counterfeit charger. But that does it translate to in real world usage? And what can we find out about charging iphones?

Efficiency Test

What I did was to record the power consumption of the charger when charging an iphone with less than 20% capacity. In this test, I assumed that the charger is putting out its maximum wattage indicated on the charger, which is 5w. This is because the iphone is likely to pull as much power as it can from the charger to fill up the battery fast since the battery is almost empty.

 

What we have here is a 6.5w consumption from the wall socket. If 5w was going to my phone, 1.5w was being wasted as heat. So, this charger is 77% efficient. Quite a decent figure here.

For a more accurate test, we can measure the output current from the USB. But that is for another time.

Any parasitic drain when left on?

Apparently, the charger has negligible drain when plugged in and switched on. This is good considering that some of us simply leave these chargers switched on even when we aren't charging anything. I like it when devices are so well designed to be able to achieve this. Saves the hassle of having the need to turn it off and on every time without the guilt of wasting energy.

 Charging with an extra long cable

For some reasons, my parents thought that it was a good idea to buy an extra long wire so that they can bring their phones to their bedside while they charge. Before I tested it, I had the expectation that the power consumption is similar to the first case above or more so as to compensate for the energy loss through such a long wire.

It came as a surprise that power consumption dropped! The iphone was deliberately pulling off less power from the same charger. It has been well established that the iphone is controls its power input quite smartly and it may have sensed that it was not able to receive the full 5w it expects. Hence, lowering down itself to the next lower rate which was 2.5w - computer USB ports give out this much.

 Assuming that it is indeed outputting 2.5w, the whole charger set up efficiency is now 64%, which is a whole 13% weaker!

Is it true that the iphone charges faster when you put it on airplane mode?

Some websites are claiming this, but looking at the power consumption when airplane mode is turned on and my screen switched off, the power consumption dropped. This indicates that the iphone is now pulling less power than before.

This suggests that the iphone dynamically takes in power from the charger to supply itself while the phone is being used. The myth that iphone charges faster in airplane mode implies that the charger is always outputting its maximum power solely to charge the battery and less power will end up going into the battery when more power consuming features/apps are used, lowering the charging speed.

 

However, this it not the case here. The lowering of the power consumption implies that the the charger is more than sufficient to supply the iphone the power it demands. So, no point switching off your phone or putting it on airplane mode hoping that it will charge faster.

I hope this is useful for you iphone users! Oh yes, avoid long wires!

Super-Max Super Stainless Blue

Finally finished my pack of 5 Super-Max Super Stainless Blue double edge blades.

I think I took about 3 to 4 months to go through that little 90cent pack which works out to be about 3 weeks per blade and approximately 7 shaves per blade. I didn't change out the blade because I felt a drop in sharpness, but rather, it was because I was bored of it.

Longer than normal Super-max stainless steel Blue blades.

While the other blades I tried seemed rather mundane and worked just as it should, the Super-Max stood out because it was just a little larger than other blades, causing it to bend at the sides of the blade when screwed down into my Rimei budget razor. Most of my blades bend just so very slightly at the edges but the Super-Max Stainless Blue bends it so badly that it sometimes tear off a small portion of the blade. When that happens, the blade becomes straight again. Ironically, that makes things well again.

Could it be razor specific?

It may be. The Rimei razor head has notches at the corners of the head to keep the blade centered. Most blades will sit snugly between these notches with a tiny amount of bending at the sides. It is visible if you scrutinize it but no matter, most blades feel just as good as the other. I think the slight bending do help in keeping the blade rigid since the blade edge is quite exposed. I suspect that other razors which do not rely on these notches are going to be just fine when used with the blade.

Would I recommend it?

Not really. It was my first pack of blades I bought when I first started with double edge shaving. Since then, I learnt that it was possible to get a variety of brands from local shops and many of these brands are cheaper and fits well. I believe that razors and blades are very precise tools and the moment they are not made properly, it will affect its performance. Being bent at the side means that the effective shaving length decreases and you may have perform more passes, eventually leading to more irritation. Otherwise, the shave is not memorable.

Choosing a good charger for your Ni-MH rechargable battery / Ikea LADDA battery charger

Several years ago, I picked up an interest in rechargeable batteries because I think they offer so much convenience and value for money over normal disposables. It may be more expensive at the start, but subsequent re-charges brings down the cost way below disposables. With today's high drain devices such as cameras, handphones and torch lights, rechargables actually outperform branded alkaline batteries.

Rechargeables batteries, while they are very good, they demand some care in order to maintain their high performance. One of the most basic way is to choose a good charger. To make things difficult, not all branded chargers are good.

Here, I'll list down the crucial features you should be looking for:

1) Charging speeds come in a few flavours.

15min "high speed" charger
These are speedy chargers that often come with a 15min timer. They are really good if you need to recharge your batteries in a rush, but they are very bad for your batteries. Charging at such speed forces a lot of current into a small battery and in turn, they get extremely hot. These chargers fry your batteries with every charge and you won't get much battery longevity using these.

Overnight chargers
Ok, so fast chargers are bad, so slow chargers should be good then? Nope. Overnight chargers are typically "dumb" chargers - they do not know when a battery is full, so manufacturers use very low current to charge the batteries. Adding more energy into the battery after it is full also causes the battery to wear out faster, but not as much as those 15min fryers. Overnight charging is just too long! Who waits that long!

~2 hour "fast" charger
These chargers are often able to detect when a battery is full and stops right there. A 2 hour charge is actually the optimal charging duration because it is slow enough such that the battery does not get too hot during charging and it is fast enough for an accurate battery charge detection.

2) Battery charge detection

Built-in timer (no detection)
By far the worst type. You either end up force feeding your battery or end up with a partial charge.

Temperature
Not accurate at all. Batteries typically rise in temperature as they reach full charge, but detection is difficult.

Negative Delta V detection
Ni-MH batteries dip slightly in voltage when the battery is full. When the charger detects this dip, it stops the charging. This is extremely important because it is able to charge up a high capacity battery and/or partially depleted battery to its full capacity, every time.

3) Dual cell charge / Single cell charging

Manufacturers sometimes try to save cost by charging 2 slots at once. This means that you'll need to put in 2 batteries before it charges both. This is terrible because batteries may have started off with an uneven charge. So, it is important to choose a charger that has dedicated slots for each battery!


So, after saying so much, do I have a recommended charger?

If you don't mind spending more for a sophisticated charger that does a lot more, get a Maha Powerex MH-C9000 analyzer/charger. Be warned, you'll get to set your own charging rate. At about sgd$100, you get features to break-in new batteries, run capacity tests and more.

Otherwise a $30 Ikea LADDA battery charger is actually very good. It was reviewed in Candlepowerforums. It comes with all the basic features of an excellent charger. At $30, you won't find other chargers that can match it. It's nice to discover hidden gems which are not well marketed but are actually very good.