BeigeJournal

Do you consider yourself some sort of geek or nerd? Do you understand power factor? If you answered yes, you need a Kill A Watt power meter. I mean, unless you already have some really expensive meter from Fluke or whatever that does the same thing, in which case you can skip it. Or if you live in some part of the world that does not use 120 volts or uses different electrical connectors than the United States, because this is a product for the US market.

The Kill A Watt is an electronic meter that measures volts, amps, VA, true power, frequency, power factor, and elapsed time and total kilowatt-hours since it was plugged in. Made by P3 International, the P4400 is rated for 125 VAC, 50/60 Hz, 15 A, 1875 VA. I paid $50 at the time I bought mine but they are running about $35 currently. It’s a box with three-prong plug on the back, socket on the front, LCD, and buttons to select which measurement to display. It is intended as a consumer product rather than some sort of industrial measurement equipment, and its build quality (it’s an indoor-use product), capabilities (120V, single phase, 15A, claimed 0.2% accuracy) and price (very low) reflect that. There are other consumer-oriented power meters out there, but as far as I know this is the only one with features like power factor and is the cheapest besides. Realistically, probably most people geeky enough to buy a meter to measure their TV set’s power consumption are probably curious about its power factor, too, and if you aren’t, we can’t make you press the PF button.

It is conceivable that an ordinary grid-connected consumer could, after making changes in her usage based on the actual data from the Kill A Watt, save enough power to eventually pay for the meter. Particularly if measuring what it actually costs to run leads you to get rid of that ancient freezer in the basement. Off-grid people will probably find it very valuable. It could pay for itself immediately if you use it to size a UPS, inverter, or generator based on actual data rather than just buying a really big one to be sure. The price is low enough, though, that it is a fantastic geek toy that does not necessarily need to be justified financially. That was my reason for buying it, as someone who spent a few years in the electrical and computer engineering department before ending up, eventually, with a chemistry degree. I have made some power saving changes in appliance usage based on the data, but not enough to pay for the meter anytime soon.

It is interesting how low the power factors of consumer compact fluorescent lamps are, usually below 0.6. Most small electronic devices have very low power factors, as do small motor appliances like humidifiers and fans, which can be below 0.5. The vacuum pump at work has a PF of just 0.33 and draws 6 amps. We residential users, of course, don’t pay for power factor in the USA, so this is more of academic than financial interest. On the other hand, high power devices may have some attention paid to power factor just to keep the current draw manageable for home use. My microwave draws 14.8A, 1605W, and 1700VA for a power factor of 0.94. My wet-dry vacuum draws about a kilowatt running with the hose on and unrestricted, with a better than 0.9 power factor, for some 9 amps. (With the inlet fully blocked it’s down to around 900W.) In the world of vacuum cleaners, with ludicrous “peak horsepower” figures advertised, it is nice to be able to measure true input power. It is also handy to monitor the input power to battery chargers to get at least some idea what they are doing without having to hack into the connection to the battery. You can at least distinguish the battery cookers from the more intelligent chargers. You can measure the power consumption of audio and video equipment when it is turned off, and be occasionally surprised by how high it is. My cable TV box is nearly the same on or off, but turning the stereo receiver off saves 14 watts.

Using the ability to integrate kWh over time the average power consumption of devices than cycle on and off, like refrigerators (100W, in my case), or systems with irregular consumption, like computers with monitors that go to sleep much of the time (120W, in my case, including a small TV set and the audio mixer) can be measured.

The Kill A Watt works well. If you are living off grid, or are trying to determine what size UPS to buy, you need one. If you have an ancient refrigerator that you are kind-of using, you might want to find out what it is costing to run. You might just decide that you don’t really need it. Otherwise, it is probably a geek toy, but a superb one. Highly recommended.

I received a Dremel Lithium-Ion Cordless rotary tool as a gift recently. (As far as I can tell the tool itself is the model 800 and the kit it is normally sold in is the 8000-01.) The Dremel is a traditional gift for anyone who you think would like a power tool, but you’re not sure which one exactly. I can tell you that I was happy to get one.

The Dremel is a tool of a thousand uses, although it was never obvious to me which, if any, of those uses were of use to me. Now that I have one and have a bit of experience using it, I can recall a number of projects that could have been done faster, more easily, and probably better with the Dremel than with hacksaw, file, or sandpaper. Aside from some fooling around (Hey, can it cut this? Answer: Yes) my first project has been a brass belt buckle that the plating had partly worn off of. I had spent some quality time on it with some steel wool attempting to remove the remaining plating to get a uniform appearance, with only partial success. With the Dremel I polished it up quite nicely in two evenings.

I’d be a better reviewer if I’d actually used a corded Dremel as well, but I haven’t. The Li-Ion cordless seems powerful enough and is reasonably light and easy to manage. With a bit of practice I have gotten used to the location of the center of mass and found it easy to manage on the relatively intricate task of polishing the corners and edges of the belt buckle mentioned above. The flexible shaft (which I do not have) is compatible with this model, though the manufacturer admits that the added friction will reduce battery life. Some of the attachments, including the 2217 tool holder, the 330 router, and 231 router table are not compatible with the Li-Ion Dremel. The 212 drill press requires an adapter.

Battery life is excellent. I’ve done over 45 minutes of fairly continuous work without running the battery completely down. The tool has three LEDs to give an indication of remaining battery capacity. I think that most of us casual users will be run down before the battery is. Certainly, if you work on bigger projects involving endless hours of grinding away at the workbench you’ll want a corded model, but the Li-Ion Dremel is not only convenient but capable of taking on relatively lengthy tasks. Recharge time is three hours.

Li-Ion is currently overall the best available rechargeable battery chemistry, and one aspect that might be considered a disadvantage I consider, in practice, a great advantage: Li-Ion batteries are spectacularly intolerant of abusive charging. Although primitive “battery cooker” chargers will substantially shorten the life of nickel-metal-hydride and (to a somewhat lesser extent) nickel-cadmium batteries, they will survive long enough that most products using NiCd or NiMH batteries ship with what I consider unacceptable chargers, with good chargers shipped only with the highest end equipment, or available only at extra cost, or sometimes just unavailable for some proprietary battery packs. Li-Ion batteries will catch on fire or even explode on the first charge cycle if such a primitive charger is used. Thus manufacturers are compelled to offer only decent chargers for Li-Ion. I have done no sophisticated analysis of the Dremel Li-Ion charger, but it seems to behave as one would expect, charging at a reasonable rate (I measured input power while charging at 7 watts) and shutting off when it decides the time is right.

This model has continuously variable speed, from 5000 to 35000 RPM. The lowest setting is off and it is possibly a bit too easy to accidentally bump the control, turning the tool on to low speed. It is something to be aware of. There is a button to lock the shaft for tool changing conveniently located near the shaft. This too is arguably a bit too easy to accidentally bump while the tool is running, but the tool does seem to be able to survive the occasional accidental light tap on the lock while running.

In an effort to keep the price down the Dremel kit contains a relatively small assortment of accessories, including a few grinding stones, some cutting disks, small and large drum sanding attachments with some sanding drums, some sanding disks, a carving cutter, drill, 401 and 402 collets, polishing wheels, and some felt polishing wheels but no polishing compound. It is certainly enough to get started and get a feel for the capabilities of the tool, after which you can buy whatever you find you need. Like the other Dremel products it comes in a nice plastic case.

I’m very happy with the Dremel. I always wanted one, and I have already found it more useful than I thought it would be. The Li-Ion cordless model, while more expensive than the others, offers freedom from the power cord while still light and powerful, with adequate battery life for all but the heaviest use.