Where I live, in the Kansas City area, electricity to my home is rated at about $0.12 per kWh. This rate doesn't change based on the time of the day or the day of the week. Given the static electrical rate, I was looking at simple metering devices that I could use for not only monitoring how much electricity is consumed by my PHEV Prius when it's charging, but also as a quick & easy means to determine the actual cost of charging, as it relates to my per kWh rate from the local utility. I've used the Kill-O-Watt meter from P3 International for measuring other devices around the house & at work & was thinking this might work well for monitoring the PHEV Prius too. It's a fairly simple device where you just program in the kWh rate & it keeps a running score of the total power & costs consumed. According to the manufacturer's page, it says the Kill-O-Watt meter supports up to 15 amps of max power at 115-125 VAC & the Prius owner's manual (pages 80 & 90) states that a full PHEV charge requires 12 amps continuous for about 2.5 to 3 hours. The Prius owner's manual is very explicit about the importance of not using an extension cord (page 79) which makes sense given the potential for electrical shorts or overheating, but I don't think that advice applies to a device like the Kill-O-Watt meter. An electrician once told me that circuit breakers & extension cords are designed to be safely operated at up to 80% of their rated maximum. If I take 15 amps (the max rating for the Kill-O-Watt meter) and multiply that times 80%, I get 12 amps, which just happens to match what the PHEV draws while charging. Am I overlooking anything here that would create a safety risk with my simple math on this, or does anyone have a suggestion for an even better metering device that is relatively inexpensive (< $100)?
My Nissan Leaf Forum • View topic - Using my Voltec charger on a Leaf? and Roadburner440's posts at http://priuschat.com/forums/chevrolet-volt/100570-looks-like-some-more-volt-battery-fires-7.html might prove insightful. If you do it, I'd definitely make sure nothing's getting overly hot after a few hours of charging. Fortunately, the PiP shouldn't be drawing power at full amperage for >3 hours.
From the Kill o Watt GT (P4480) user manual specs page. GENERAL SPECIFICATIONS POWER RATING 120 Vrms ± 10%, 50/60Hz POWER CONSUMPTION Max. 0.8 Watt Ratings 15Amp (1980 Watts) Resistive and Inductive, 600 Watts Tungsten, 1/3 H.P. 120V.A.C. L/W/H 72mm x 73.4mm x 139.5mm WEIGHT Around 245g Note: 1. The specification is based on sine wave and resistance load. Note the "Note" and the "600 Watts Tungsten" rating. This is only 5 amps continuous. Poor contact of the plug to socket mating surfaces leads to excessive heat and meltdown or fire. I always upgrade from 15 amp to commercial heavy duty 20 amp sockets for food service equipment because of this. A solid wire clamped by a properly torqued screw is still the best way to go.
I've had inrush current arcing melt the front side of Kill-o-Watt. I suggest plugging the cord into the Kill-o-Watt, then the Kill-o-Watt into the wall.
Used a kill-o-watt from work to monitor my Volt for a while. No problems. Volt manual also suggests no extension cords, but a good 10/3 or 12/3 extension works fine (14/3 may get warm).
And another Volt poster noted the case of the kill-a-watt had started to melt after using it a week on the car.
At least a couple folks have had problems with the kill-a-watt when pulling 120V at 12A charging the Volt. Others have not had a problem. I have used a Watts Up daily for over a year to charge my Volt for several hours at a time overnight without any problem. It stays cool and seems well built. It can also be configured with kWh pricing info.
Hadn't heard of that meter before, so looked it up. Certainly sounds like a high quality choice, but they sure are pricy compared to a Kill-a-watt https://www.wattsupmeters.com/secure/products.php?pn=0
This is old school. All the new switched mode power supplies have circuitry that makes the power factor 1.0 which is a purely resistive load.
When my plug timer's relay failed, the repair man asked my what have I had connected. I told him an electric motorcycle, which draws 1.7kW. The timers is rated as 3600W, but he told me, that the charger is an inductive load and that the timer only handles 1500W of inductive load. Even so, he repaired it under the warranty, because the product box nor the manual defines anything like that, only that it handles 230V, 16A.
From everyone's feedback so far, it sounds like the Kill-O-Watt (model P4400) should work in theory, based on the experience others have had with the Volt given the similar charging characteristics both cars have in common. I know it's common to plug the Kill-O-Watt meter into an extension cord, since the meter will otherwise cover 2 full outlets in a duplex power receptacle, given the meter's size, but since I'm going to have a dedicated duplex receptacle on a stand-alone 20 amp circuit just for charging my PHEV Prius, I'm thinking that plugging the Kill-O-Watt directly into the power receptacle and the charging cable directly into the Kill-O-Watt with no extension cords should be safe. I think that cwerdna's suggestion of checking how hot it's getting after at least an hour or two of charging is a good idea. And like seilerts pointed out, arcing from in-rush current is a problem that I've seen as well with another Kill-O-Watt meter I already own, although I've never managed to melt one yet. And as Jeff N suggested, I hadn't previously heard of the Watt's Up series of meters, but I'm going to check those out. I'm not opposed to paying a bit of a price premium if the meter is constructed of higher grade materials, especially if it could reduce the chances of part of the meter melting. But, I'd have to figure out a way to do an apples-to-apples comparison of Kill-O-Watt and Watt's Up meters to make an informed decision on it.
On that note, to quote from the post at My Nissan Leaf Forum • View topic - Using my Voltec charger on a Leaf? Ingineer is pEEf here. Based on his work such as EVSE Upgrade - Products and http://www.nytimes.com/2011/10/16/a...t-leave-well-enough-alone.html?pagewanted=all, I trust his opinions and knowledge. He's done some amazing work to mod his Prius and knows how to fix certain problems on the Prius (e.g. 2nd gen Prius bad combination meter issue w/o replacing the entire board).
