Dan's Data letters #168
Publication date: 29 June 2006.Last modified 03-Dec-2011.
You'll need a fire hose and a bench grinder...
I do know that you're not the author of the Women's Weekly "How do I get rid of this nasty stain on my shag pile" section, but I have a not dissimilar problem that's in need of some attention.
My wife left four AA Duracell batteries in her external camera flash for an extended period of time. Whilst the batteries' use by date is marked as 2008, methinks being left inside the flash has not been kind to them – they've spat much of their contents over the interior of the battery compartment, and have corroded the contacts slightly.
I've cleaned what I can of the gunk out of there, rather carefully as I assume it's at least mildly acidic. She Who Must Be At Least Listened To has suggested using a solution of baking soda on cotton buds or something similar to get the rest of the crap out. It sounds reasonable to use a basic solution to neutralise said acidic gunk, but perhaps you've come across this phenomenon before and have some suggestions?
Yep, I've Googled, but my fu may not be at its best today – I get SFA that helps my feeble brain.
This seemed helpful, but now I'm doubting my assertion that the residue is acidic – of course, the term "alkaline battery" may be a hint...
The use of alcohol in a reply to this post seems unlikely to be useful.
The Duracell Material Safety Data Sheet (PDF) confirms that the goo is alkaline (unless my high school chemistry has deserted me and a hydroxide ain't a base), so I suppose that vinegar or some other weak acid would be the go?
Brad
Answer:
Yes, the goo that comes out of leaking carbon-zinc batteries (not, as you say, alkalines) is acidic, but so's lemon
juice. You don't have to worry very much about getting ordinary battery goop on your hands unless you've got unusually
sensitive skin. Do feel free to use rubber gloves, of course, but the stuff isn't alien
blood; just don't let it sit on your hands - alkaline goop
is a strong enough potassium hydroxide paste that it certainly ought to scald normal skin, given time - and for Pete's
sake don't rub your eyes before washing your hands.
(Skin resists some quite strong acids very well. People who splash themselves with car battery acid commonly end up with holes in their clothes, but not in their bodies; your average calloused mechanic doesn't even know he's done it until his jeans fall apart. Try the same trick with moderately strong nitric or even quite weak hydrofluoric acid, though, and you will not be a happy camper.)
There's no actual need for you to neutralise anything here, though; it's not as if you just sloshed some scary acid all over the floor and now need to sprinkle sodium bicarbonate everywhere (industrial facilities that have open acid drums around often have them standing in a snowdrift of something-or-other carbonate or bicarbonate, to deal with spills and leaks before people even notice them). All you need to do is wash the goop out. The best solvent for doing that, since carbon-zinc and alkaline cells both use a water-based electrolyte, is water.
This is easier said than done for electronic devices that you don't want to take apart or drown, of course, but a squirt bottle full of warm tapwater can still do a good job when wielded with care. Likewise a damp dishcloth. Just make sure you don't wash freshly re-dissolved electrolyte into the flash; most electronic gadgets will survive being dunked in clean water if you just put them somewhere warm and breezy to dry afterwards, but all bets are off when something corrosive gets into the works, especially if it gets to stay there for a while.
Battery electrolyte re-dissolved in water probably won't do as spectacular a number on the flash as cola would, but that's not saying much.
So, anyway - wash it clean as best you can, then clean up the contacts, which are probably a bit corroded. A mild abrasive will do the job - reach in there with a pen eraser, or a bit of emery paper on the end of your finger, or whatever. Take care not to squish springy contacts flat, or yank them out.
If the flash doesn't work after you've done this (leave it in the sun for a while first just in case it's gotten damp inside), you could try taking it apart to assess the damage.
Note that even small photo flashes contain reasonably high value, high voltage capacitors, which may retain charge for ages after the flash was last used, and which can give you a nasty belt (possibly a fatal one, but really only if you're exceptionally talented). All properly designed flashes should be built with drain resistors that slowly leach power out of the big cap(s) and should make the flash safe after a few hours, but not all flashes are properly designed, or properly made.
So if you crack the flash's case, make discretion the better part of valour and keep one hand behind your back while you tinker with it.
Or hire a dwarf or a half-orc
I have been using my Sony Clie TJ-37's camera at work to troubleshoot and set up our motors. The camera in the PDA is an absolute piece of crap, but it does see IR very nicely, has a big real time display, and allows me to see what the IR LEDs are doing.
But the PDA is about ready to die, and I don't want to spend $400 to buy a PDA with a camera that may or may not work. I'm considering replacing it with a cameraless PDA - a junker Z22 that should do the trick, or I might even go the retro route and get a Visor Edge from the 'Bay. Frankly, I was surprised that the Clie camera saw IR, but it's such a poor camera that it's no shock that they left the IR filter out.
Any suggestions? I could buy an IR imager for a few grand, but I don't think anyone will go for that idea either!
Mike
Answer:
Actually, many consumer digicams still have no IR filter, to the best of my knowledge - or, at least, they have one
that lets through quite a lot of near-IR. That's all you need to see remote control LEDs. People who want to do actual
IR photography are more demanding (and are often using
pro cameras with higher quality IR filters, which are exactly what they don't
want).
Anyway, all but the cheapest consumer cameras now also have good preview screens, so your shopping options should be pretty much wide open. Just take a remote control with you to the camera shop and see how different cameras see it. You could also use a webcam, or one of those little plasticky motion video cameras that takes a memory card. A lot of those can do 30 frame per second recording these days, up from the 15-odd fps they did when I last reviewed one, years ago. They may not have a fast enough preview screen, though - and their preview screen will be a teeny little thing. If you want proper between-VHS-and-DVD-quality 30fps recording from a card-cam, I think you probably want a Sanyo Xacti. But, as I said, there are umpteen cheaper digital still cameras, with or without a worthwhile movie mode, that'll also do the job.
The fact that my EOS-20D can't see near-IR is one of the few things I don't like about it, though it does make everyday pictures look better (cameras that can see IR have spectral response that goes blue, green, yellow, orange, red, bluish-white, which is even worse than the red, orange, yellow, green, blue, bluish-white of film).
Oh, and at this juncture I simply must link to this again. It's completely useless in this context, but it's just so neat.
Are these too heavy?
I have a rather large photo shoot ahead of me this weekend. I intend to blow through about 1500 shots per day with my Sony DSC-F828 digicam using a couple of Microdrives. The best the InfoLithium battery can do is 500 shots, or roughly enough to fill a 2Gb card. I am familiar enough with electronics to build an outboard battery, but I am concerned about a couple of items.
1. The voltage the plugpack puts out is 8.4V. Unless I am mistaken, the nominal voltage of a rechargeable battery is 1.2. 7*1.2=8.4, so I think I'm set there.
2. Since the camera uses the plugpack to charge the InfoLithium battery as well as power the camera, what will happen when the voltage from the battery pack starts to drop off? If power draw remains constant, as the voltage drops won't the current increase, possibly damaging the camera? Normally I wouldn't be concerned, but A; 7 D-Cells can put out rather a large amount of current and B; I doubt the camera is designed to be about to cut off the charger jack since it's unlikely the voltage would ever sag that much on a mains powered regulated AC/DC supply.
Aaron
Answer:
Generally speaking, if you're making an external battery that you're going to plug in where a plugpack normally connects,
all you have to do is match the plugpack voltage and you'll be fine.
Note that for a significant amount of their discharge cycle, NiMH cells are likely to deliver more than 1.2 volts per cell - more than 1.3V when freshly charged. This isn't likely to hurt the camera, since it's a lousy electronic device that can't handle 10% more input voltage, but it can be significant in some situations. Don't freak out if you stick a multimeter across your new pack and it reads 9.2 volts after charging.
This, by the way, means that the camera will probably work fine from six alkaline cells, which is a much cheaper way to build a battery, and can thus be very attractive if you don't intend to be using the new pack very often.
The old high-drain cameras (which were all that existed when I wrote my outboard battery piece; these things were the state of the art in the consumer market then) were a pretty hefty load even for big alkalines (Ds, F-cell-filled 6V lantern batteries), so running them from alkalines wasn't a great idea unless you made some kind of huge series-parallel pack.
Today, though, the F828 runs for quite a while from its entirely typical 1.2Ah lithium ion pack. You get, what, three hours even when you're shooting quite a lot and using the flash? So alkalines are likely to work very well. I wouldn't be surprised if six C alkalines gave you four times the standard battery's life, and six Ds gave you ten times.
The usual disclaimers apply, though. If you try alkalines and the camera catches fire after 50 shots, I never said any of this.
When the battery pack voltage starts to sag, it's likely that surprisingly little will go wrong.
NiMH cells have a cliff-like discharge curve, which means they're pretty much flat by the time they drop to 1.1 volts per cell. At that point the camera will probably still be working and charging its own battery, though you may notice symptoms like slower zoom and focus motor action, and a dimmer screen. Or you may not.
As you say, the camera doesn't expect its plugpack to drop in voltage, and so it may indeed behave oddly when the pack's going flat. I'd expect something like turning off inelegantly when the flash starts to charge, and corrupting the file it's writing to the memory card as a result. I wouldn't expect the whole card to be munged as a result of this, though, and I'd be very surprised if anything was permanently damaged by low input voltage.
I think Acme make them
Any ideas whether BioPerformance is a crock or a genuine thing?
Eric
When Eric originally e-mailed me, the BioPerformance site was up and being promoted by various "affiliates" with their own URLs, as per normal for many operations whose principal product appears to be the opportunity to sell their principal product.
Now, staggeringly, it would appear that some miserable old government regulators have completely unfairly shut down, once again, the honest and hard-working people who just want to bring the world "gasoline pills". Even though the pills aren't as blatant as they used to be.
Will nothing please these regulatory tyrants?
Zero to drunk in...
I noticed you referenced Everclear in an article.
[Readers - are you bored? Play Find The Link! "View Source" is cheating.]
Have you got a source on it here in Australia?
Brad
Answer:
No. I think it's illegal, or so heavily taxed as to be functionally illegal, in Australia.
(Everclear is also unbuyable in many states of the USA. Not just Utah.)
This is because Everclear is high-potency ethanol, and like many other innocent little molecules, C2H6O is a political and regulatory problem.
Most countries, including Australia, have alcohol taxes based on the concentration of the ethanol in a beverage. That's why spirits here, and in a lot of other countries, is almost all 38 to 40% alcohol.
Tax structures differ for stronger beverages, but they're pretty much always more and more punitive as the alcohol concentration increases, perhaps as part of the age-old battle between moonshiners and revenooers. Anyway, the result is that one litre of 60%-alcohol hooch costs considerably more than 1.5 litres of 40%-alcohol.
A given legislature may not even have a legal category for "beverages" like the most common version of Everclear. That's 95% ethanol, which is the highest concentration of alcohol that can be created by distillation - it also won't dilute itself too rapidly by sucking water out of the air.
(If you set up your own still to get rid of the troublesome water in commercial spirits, by the way, you should easily be able to make 70% alcohol. Getting better than 90% at home may be a bit trickier, unless you cheat by dropping water absorbing pellets through your brew.)
If there is a category for booze this strong, it'll probably be taxed out the wazoo, to discourage the more-is-better kind of young and enthusiastic drinker that's over-represented in emergency room statistics (for various combinations of motor vehicle accidents, alcohol poisoning, street brawling and multiple sexually transmitted diseases). Which is a shame for those of us who just like to be able to buy purified chemicals.
Straight 95% Everclear does not really count as a beverage, of course. It's much too strong for ordinary drinking. Even hardened alcoholics with iron esophagi don't get much value from drinking 95% alcohol; unless you've got a decent amount of liquid in your stomach already, ethanol that strong will just irritate the stomach lining severely and cause the stomach to secrete protective mucus, which inhibits absorption of the alcohol, kind of defeating the purpose. If you're a normal human and have to follow the stuff with a great big chaser, you might as well be drinking more dilute alcohol in the first place, theatrics aside.
Of course, lots of people buy 95% ethanol all the time - it's medical alcohol. That's what some Everclear's bought as, too; it's a cheap way to get high potency ethanol for your garage science experiments. But, as med students down the ages have discovered, it goes the other way too - 95% medical ethanol can be added to drinks, or drunk straight on a dare.
You can't buy medical alcohol at the local liquor store, of course, but you should be able to get some from pretty much any scientific supplies place that sells reagents. They ought to stock ethanol at various concentrations - 70%, 95%, even 100%, though that'll start diluting itself as soon as you crack the bottle, and possibly before, depending on how vapour-proof its packaging is.
Needless to say, Australia has goofy regulations regarding who can buy "chemicals" from scientific suppliers, even if said chemicals are about as dangerous as table salt. But getting an account with a scientific supplier still shouldn't be too difficult.
All "potable" ethanol, though, is still subject to liquor taxes. Since "methylated spirit" in Australia is, I believe, now pretty much all ethanol plus non-alcohol denaturants (in other words, it isn't actually literally "methylated" by the addition of methyl alcohol at all - see the end of this page), it's possible that you can use that for scientific purposes, after suitable filtration.
If you're looking for a beverage, though, I suggest that any recipe that says "buy 50 litres of meths and some Brita water filters" is not worth following.
(Though, as is now well known, water filters can make ghastly "plastic jug" vodka into spirit that doesn't taste like paint stripper. Regrettably, Australia's liquor laws would appear to make plastic jug vodka uneconomical to sell, based on the fact that nobody here seems to sell it. This idea is now popular enough, though, that you can buy allegedly superior commercial products that do the same thing.)
