Dan's Data letters #112
Publication date: 21 June 2004.Last modified 03-Dec-2011.
All things die
My last two cell phones have been small flip phones, because I need a small form factor and I want the keys and screen protected while the phone is not in use. But these units have small batteries that don't seem to last. I get about a week of use out of a charge (with phone constantly on) when they're new, but after 15 to 18 months I have to charge the battery more and more frequently (I'm down to about 2 days per charge now). Both phones are the from the same manufacturer and use lithium ion batteries. Is there anything I can do to extend the service life of a new battery, or rejuvenate the battery I do have? Or is this performance degradation typical of the small form factor or type of battery?
Should I be shopping for a phone that uses a different battery type?
I'd really like to stay with the small flip phone form factor. And I need to have the phone on at all times.
Charlie
Answer:
The battery lifespan you're getting is pretty normal for lithium ion. All batteries wear out, and Lithium ion batteries
that haven't even been used can be expected to be severely degraded by internal oxidation after two to three years.
And that's two or three years after they're manufactured, not after you buy them.
Using a Li-I battery normally doesn't make it age any faster, but the warmer it is the sooner it'll die. So don't leave your mobile phone in the sun. Apart from that, there's nothing you can do but buy new batteries when the old ones die, and try to buy batteries that haven't been sitting on the shelf for a year. Good luck decoding the serial number to figure out the manufacturing date.
Lithium ion batteries in storage will last longer if they're stored with about a 40% charge, but the difference isn't large, and is irrelevant for a battery you're actually using.
If you don't like the short lifespan of lithium ion, you're in trouble, because it's pretty hard to find a phone that doesn't use Li-I these days. NiMH lasts longer than Li-I, and the fifty-year-old NiCd chemistry lasts longer still, by a large margin; if you've got a good charger and only charge once every several days, you may be able to get decades of life out of a NiCd pack made from modern brand name cells. But the energy density of lithium ion (energy per unit weight) is about twice as good as NiCd (and about 1.5 times as good as NiMH), so despite its fussiness and lousy lifespan, the portable device market has turned to Li-I en masse.
Peltier conditioning
I read your articles about Peltiers, and am wondering how effectively one could be used to cool a dorm room if you strapped an average CPU cooler/fan on each side, with the hot side set to be blowing out a window (with insulation around the rest of course). Do Peltiers have enough get-up-and-go to do that?
Nick
Answer:
If your dorm room's the size of a hatbox, this setup will work passably well. Any bigger, and the miserable thermal
transfer capability of even an array of Peltiers will mean they'll make much less difference to your comfort than
just leaving the darn window open.
Plus, Peltiers are very inefficient. You have to put much more power into a Peltier to move a given amount of heat than you'd need to move the same amount of heat with phase-change circulating refrigerant cooling. In both cases, you have to get rid of the heat you've moved plus the energy used to operate the system on the "hot side", but phase change systems let you put the hot side somewhere else; Peltiers have their hot side right next to their cold side, which means the hot side inescapably directly heats the cold side, and also makes it very difficult to get an efficient heat sink on both sides of the device. You can use a water block on each side of a Peltier with remote radiators, but that's getting a bit complex, and the whole exercise becomes clearly pointless when you look at the baseline comparative efficiency of Peltiers and regular refrigeration, as used by normal air conditioners.
The smallest window-mount air conditioners on the market have a (very fuzzy) half-horsepower input power rating and are good for about 5000 British Thermal Units per hour of cooling (the downright weird BTU hangs on as a description of heating and cooling power even in some metric countries, including Australia). One BTU is 1055 joules, and a joule is a watt-second, so these small window air conditioners can shift around 1.47 kilowatt-hours of heat out of a room in an hour.
For a Peltier device to actually be cooler on one side than on the other, it has to be running at rather less than its maximum thermal transfer capability. You're unlikely to be able to shift even fifty watts through a Peltier and keep the two sides very different in temperature (if the cold side's only three degrees below the outside ambient, you're obviously not going to get much cooling no matter how many watts the thing can theoretically shift), but let's be charitable and say that a Peltier device can shift 50 watts in a room-cooling application.
50 watts for an hour is 50 watt-hours (stop me if I'm going too fast for you); you'll thus need more than 29 of these unrealistically effective Peltier devices to equal a little air conditioner, and they'll draw a lot more power. In the real world, you'd probably need more than 50 Peltiers, and some ludicrous cold-plate, water-block, pipe-manifold, dual-radiator setup to get the heat into and out of them.
So there's no substitute for a real air conditioner. A small window-mount unit will be pretty darn cheap - though you'll have to install it properly, with brackets and such, if you don't want to just wedge the thing in the window and hope nothing Very Bad eventuates. Portable conditioners (which just have a plate with a tube going to it that you can safely wedge in a window) typically cost more, and don't work as well.
If you live somewhere where the humidity is normally quite low, by the way, then an evaporative cooler will work pretty well; if you're not allowed your own air conditioners, you should be able to get away with an evaporative unit. They're as cheap as basic window air conditioners, you can get small portable ones, they cost little to run (all they are is a fan blowing over a big damp wick, basically), and the only maintenance they ought to need is regular water top-ups. If you live somewhere with typical summer relative humidity well above 50%, though, they won't achieve much. They're pretty much useless here in coastal Sydney, Australia, for instance.
Headphone happiness
I recently ordered a pair of Sennheiser HD 497 headphones, and they sound AWESOME. Can't complain about them at all. I just have two questions:
1) When I'm not playing any music, I can hear this faint buzzing and occasionally some high-pitched tweeting to boot. When I move the mouse, the buzzing gets louder, and it's even louder if I'm dragging something around (a window, scrollbar, etc.) FYI I'm using onboard motherboard audio (nForce2) with a cordless keyboard/mouse (Logitech Cordless MX Duo).
2) How do I wear these properly? I think I've got them on right, but I'm not sure. The "cup" of each earpiece isn't big enough to surround my whole ear (like the proper circumaural ones) but instead only part of my ear. From experimentation, the best way I've found is to wear it such that the tops and backs of my ears hook up under the top and back sides of the cup – which feels comfortable and sounds great, however the speakers aren't directly opposite my ear canals. Or does this not matter?
Jonathan
Answer:
The noises you're hearing are the motherboard audio adapter failing to completely reject the storm of RF noise from
other components inside the case. This is normal; to avoid it you'll need to get either a rather nice sound card (better
standalone consumer cards may be good enough, or you might need a proper home studio card) or an external (USB)
audio adapter of some kind.
The 497s are hybrid 'phones like the HD 212 Pros I reviewed the other day - they look like circumaural 'phones, but as you say, the earpads are too small to actually go around your ears. They just sit on top. If your particular ear geometry makes it comfortable for you to tuck yourself into the earpads, as it were, then it's fine to go with that.
Mighty (unreliable) midget
I got one of those nifty Antec Aria cases, with the intention of building a tiny powerful PC. I've got the following hardware in there:
Gigabyte K8VT800M mobo
Athlon 64 3000+
Radeon 9800
Sound Blaster Audigy LS
PCI Wi-Fi card
DVD-RW drive
Two SATA 120Gb HDs in RAID 0 configMy question to you is, is the Aria's measly 300W PSU adequate to power all this under demanding conditions? Or could the "VPU recover" errors I get in Far Cry be a result of the PSU lagging under intense processing load?
I have a good video card cooler (VGA Silencer on high) but just the stock CPU cooler, and the 120mm fan in the PSU for ventilation.
I don't get lockups in Thief 3... which is also pretty DirectX 9 intensive, and I haven't had any other issues, but the levels on the 12V and 5V lines in MBM 5 are rather concerning - 11.63 and 3.33V?
Daniel
Answer:
Yes, the PSU could be at fault, though the fact that only one game fails would seem to suggest a software problem.
And 3.33V for the 5V line should mean your computer wouldn't work at all - though it's bang on for the 3.3V line,
of course. If that's actually what you're getting, I'd guess the hardware monitor/BIOS combination is miscalibrated.
Getting back to the PSU - I don't know what its real specs are, but you've got enough of a stacked system that I wouldn't be surprised if it was gasping. Could be something else again, though - overheating, bad RAM, a static-damaged video card, blah blah. It doesn't sound like a RAM error, though; if it's a hardware problem at all, my guess would be PSU first, overheating second, video card third, voodoo fourth.
Normally, I'd just recommend trying a new PSU on general principles, because as I've said many times before it's a good idea to have a spare power supply on your shelf anyway, and they don't cost much. But the funny little PSU the Aria uses is not commonly available, and I don't know if you could find a beefier one anywhere.
That said, though, you could get a decent 400W-plus ATX supply, unplug the stock PSU and just run the computer with the lid off, or cables snaking in through the hole where the regular PSU mounts, or whatever. The Aria PSU has standard connectors, so it should be possible to run the computer from an outboard ATX PSU with no trouble. If it works then, you have the choice of sticking with that ugly setup, or downgrading your computer so it works with the small PSU, or transplanting your components to a larger case with a regular PSU.
Before you do any of this, though, try taking the lid off and pointing a desk fan at the computer, to see if it's happier when it's cooler.
Hundred watt per channel headphones
Your article a way back put me on to one of those sweet Cmoy amps. It does its stuff with my Senn 555s no worries. But I want more. Seems that upgrading to a killer audiophile grade headphone amp is gonna be an expensive exercise.
So what if I just buy an el-cheapo full size amp on eBay, one well capable of causing my phones to explode, then buy some (cheap) device to convert the fully amplified signal into a more palatable one? Have you heard of this being done before? I know there are 'phones out there that can nearly take a loudspeaker level output, like AKG K 1000s, but they're not really what I'm after, or what I can afford. Using a full-sized amp would also give the added benefit of proper hardware treble and bass controls, instead of plasticky-sounding software equalisers and such.
Owen
Answer:
Yes, what you're suggesting can be done. If all you want is a headphone amplifier, though, buying a full-sized amp
and choking down its output to suit 'phones is unlikely to give you better sound per dollar than buying a dedicated
headphone amp for similar money. If you've already got a half-decent full-sized amp, of course, then an adapter
is a much more sensible proposition.
Headphone adapters for speaker output aren't common items, but they're not complex either. In the commercial arena, a quick hunt turned up QED Audio Products' now-discontinued MA18 Headphone Volume Control, and this simple adapter for the output terminals of a Grado amp.
The circuit for one of these things is very simple, though not quite just an in-line resistor for each channel, if you want the headphones to see the right input impedance.
In reality, just feeding the headphones through a resistor on each side probably would work fine with most amp/headphone combinations.
Another fan
You're a facist [sic], rambling idiot.
Facist [sic]: I can tell that you are against Germans and Homosexuals.
Rambling Idiot - how can you make this page so long? Why not do a simple bulleted list? And not get off topic?
I would have more, but I'm too lazy to browse your poorly coded site anymore. I know you can do better than a new HTML file for every ramble.
Answer:
I initially thought that Mike was taking this page seriously, as people occasionally do,
but he says not; he's talking about "little remarks about Germans and gays" elsewhere on this site.
I've got to say, I'm impressed. None of the rest of you have been able to spot these unspecified cryptic clues to my rampant, ah, anti-Teutonism, not to mention profound homophobia.
I've certainly been covering it up well, what with spending some more time yesterday evening playing with the ferocious dog that belongs to the frightfully famous co-convener of the Gay and Lesbian Rights Lobby here in Australia, where my girlfriend does volunteer work. Heck, I even went to the trouble of taking the cat there, one day. I tell you, it takes all of my strength to contain my hatred for those guys and gals every single time I go to a party with them. And now, it's all for nothing; I am discovered.
Coincidentally, my girlfriend's day job is at the Australia Centre Berlin, where of course I occasionally drop in just to make obscene phone calls to her German workmates, for all of whom I also feel the deep contempt which only Mike was cunning enough to discover.
I've told Mike all of this, but it didn't convince him; I guess he can't be fooled.
Mike didn't elaborate about what, exactly, gave me away, but I'm sure he'd love to talk to any or all of you about it. He might even explain to you what he means when he asks for shorter pages, that aren't "new HTML files".
Feel free to CC: me.
