Bad PBS, No Biscuit
In general, I'm OK with the subtle indoctrination that PBS does in the games on their website (wait, did I say subtle? I meant blatant). None of the areas where I might have differences in opinion with the people making their editorial decisions are likely to come up in a children's program (or a children's website). I object, however, to factual errors.
Yesterday, as Nicky was playing a game on EekoWorld, I had to speak up to point out something that was (to me) a pretty obvious error. For those of you who are unfamiliar with the site, the site exists to teach kids about the role they play in taking care of Earth. As such, a couple of their areas of focus are responsible energy use and recycling/garbage reduction. With those areas of focus, one of the things they highlight is using rechargeable batteries when possible. But someone working on content for them goofed. In one of the quizzes, they asked whether you should use a rechargeable drill or one that plugs into the wall. Their preferred answer was that you should use a rechargeable - because rechargeables are good. I immediately interjected to point out that they were wrong.
Battery-powered drills (I'm pretty sure I've never seen one that uses non-rechargeable batteries, but if they're out there, a rechargeable *is* preferable to them) have a couple of significant losses that make them less energy-efficient than corded drills. The first is when you charge the battery - in low voltage applications like rechargeable batteries, the peak loss in the rectifier (which converts AC to DC) is around 10% of available power. The other major loss is battery self-discharge. Battery self-discharge is the reason why your flashlight is weak or dead when you pull it out of the drawer, even though you could have sworn that it had good batteries when you put it in there (because, in fact, you did - but batteries lose charge over time due to self-discharge). For people who use their cordless tools constantly, they suffer less from leakage loss, but even for them, it's still an issue.
There's also the garbage issue involved in rechargeable batteries. If you've had any cordless tool for a significant length of time, you've had to get a new battery for it because they only last so many charge/discharge cycles.
In theory, I could see a couple possible ways that a rechargeable drill could be more energy efficient than a corded drill. If you need an extension cord, you lose some energy to the voltage drop on the extension cord - the longer the extension and the thinner the gauge of the cord, the more energy you lose heating up the extension cord (trust me, this is *not* an energy-efficient way to heat your house). So if you're using a thin-gauge 100 foot extension cord, you might lose enough to make the cordless a better energy efficiency choice. The other way that a rechargeable could be more energy efficient is if you have to generate the electricity yourself. Portable generators are a lot less efficient than the industrial-strength power generation that my father and his co-workers used to do. But if you're working at a site that doesn't have installed power, you'll probably wind up charging your cordless drill from the generator, which means that you get *all* the losses.
Yesterday, as Nicky was playing a game on EekoWorld, I had to speak up to point out something that was (to me) a pretty obvious error. For those of you who are unfamiliar with the site, the site exists to teach kids about the role they play in taking care of Earth. As such, a couple of their areas of focus are responsible energy use and recycling/garbage reduction. With those areas of focus, one of the things they highlight is using rechargeable batteries when possible. But someone working on content for them goofed. In one of the quizzes, they asked whether you should use a rechargeable drill or one that plugs into the wall. Their preferred answer was that you should use a rechargeable - because rechargeables are good. I immediately interjected to point out that they were wrong.
Battery-powered drills (I'm pretty sure I've never seen one that uses non-rechargeable batteries, but if they're out there, a rechargeable *is* preferable to them) have a couple of significant losses that make them less energy-efficient than corded drills. The first is when you charge the battery - in low voltage applications like rechargeable batteries, the peak loss in the rectifier (which converts AC to DC) is around 10% of available power. The other major loss is battery self-discharge. Battery self-discharge is the reason why your flashlight is weak or dead when you pull it out of the drawer, even though you could have sworn that it had good batteries when you put it in there (because, in fact, you did - but batteries lose charge over time due to self-discharge). For people who use their cordless tools constantly, they suffer less from leakage loss, but even for them, it's still an issue.
There's also the garbage issue involved in rechargeable batteries. If you've had any cordless tool for a significant length of time, you've had to get a new battery for it because they only last so many charge/discharge cycles.
In theory, I could see a couple possible ways that a rechargeable drill could be more energy efficient than a corded drill. If you need an extension cord, you lose some energy to the voltage drop on the extension cord - the longer the extension and the thinner the gauge of the cord, the more energy you lose heating up the extension cord (trust me, this is *not* an energy-efficient way to heat your house). So if you're using a thin-gauge 100 foot extension cord, you might lose enough to make the cordless a better energy efficiency choice. The other way that a rechargeable could be more energy efficient is if you have to generate the electricity yourself. Portable generators are a lot less efficient than the industrial-strength power generation that my father and his co-workers used to do. But if you're working at a site that doesn't have installed power, you'll probably wind up charging your cordless drill from the generator, which means that you get *all* the losses.