There is no savings by charging the batteries from the engine. Not to say it doesn't ever do that. You can see the charge direction when braking. They all recomend for maximum gains that you plan your stops so that you can slow down gradually. When you put your foot on the brake lightly it does the braking with the electric motor acting as a brake/generator. You can feel it. I try to do that. If you stop hard it still generates but also has to use the regular brakes. Some of the savings also comes from shutting the gas engine down when ever there is an opportunity. If you stop at a red light it will turn the engine off. When you take off the electric motor starts you moving and also starts the engine. When you are maintaining a consistent speed like out on the highway it will shut the gas engine off on slight downhills and use just the electric motor to maintain speed. It's pretty impressive that they are able to bring the gas engine in and out of the drive train without it being noticable. You really have to pay attention to tell when it happens. It pretty consistently gets around 50mpg no matter what the trip is. Even on the highway running at 75mph. I was surprised at that as the highway doesn't have much oppotunity for charging.
Did you build it? If I got that right, the DC generator was fed from the output so it operated as a motor? Can't help but wonder how it would perform with today's lithium ion batteries. Did it have anything to reverse the process to slow the car and charge the batteries? Maybe when downshifting?
and they don't mention that it takes more energy to CREATE the batteries and the vehicle itself than it will ever return in savings. electric cars and hybrids are a joke.
The Prius has an Atkinson cycle gas engine, a major feature for high mpg. The exhaust stroke is, in effect, longer than the intake stroke. That makes the engine more efficient. But it gives you less horsepower in the same size engine. The engine has variable valve timing. I have not seen a good explanation, but I think they can shift the engine back toward a 'normal' engine for higher HP when needed. The engine HP can be smaller (as with any hybrid) because when high HP is need both the gas engine and electric motors are used. With a smaller engine you are operating in a more efficient RPM range.
It uses a "hybrid synergy drive". It is a planetary drive that connects the gas engine, 2 motor/generators, and the wheels. There is no mechanical change for forward, reverse, high, low. The "drive" allows charging the batteries while driving, powering the drive electric motor from the other motor/generator (combined with gas engine - necessary at the high end of the speed range), and generally manipulating the "drive" so the gas engine runs in the efficient RPM range. When the batteries are charged from the engine while driving, the engine is at an efficient RPM. The engine throttle is totally controlled by computer.
Regenerative braking, as above, captures much of the kinetic energy that would be lost as heat in the brakes. It must work pretty well - the city mpg is close to the highway mpg. I assume this is a major feature of all hybrids.
Obviously it all works, as you mpg indicates.
Having the engine stop at a red light is kinda strange at first.
Measuring wattage you can use a CT amp connection, but you also need a direct connection to measure voltage, at least for loads with a power factor other than 1. I have not seen a watt meter with CTs that was very cheap. An old utility meter is cheap (but takes a little more work to connect).
You can get the newfangled modern external digital auxiliary power meters that also measure voltage and the CT's are inside the electrical panel and they're not cheap but they're easier to install than a power meter on the incoming main lines outside.
The nice thing about the concept of an electric car is that there is the possibility of eliminating the need for fossil fuel to operate it. Yes, you still need a souce of energy to provide the electricity, but that source can be derived from hydroelectric, nuclear, wind, or solar sources.
They also do not put out any pollution from the tailpipe, and are quieter.
Short answer: The Kill A Watt is a cheap way to go in some cases. Mine doesn't work on my microwave...just beeps, "overload".
15 amps max.
Longer answer...OK MUCH longer answer...based on a year of messing around measuring energy consumption.
Mike's metrology rule number 1. If you're not gonna use the answer, don't bother to ask the question.
For example, if you want to save on your heating bill, turn DOWN the thermostat. If it's already as low as you can tolerate, measuring it won't help a bit. If you can tolerate it lower, you don't need any measurement to know that it will save you money to turn DOWN the thermostat.
If you can replace a 100W incandescent bulb with a 13W CFL, the only thing that matters is that you still have some savings left after you amortize the added cost of the CFL over its lifetime...which is often WAY shorter than what it says on the package.
So, why do you want to measure consumption? For most of us it's an attempt to reduce costs. Most residential users, at least in the US, pay for WATT-hours. You want to measure what you pay for.
If you use a clamp-on amp meter and multiply amps by the voltage, you get VOLT-AMPS. You don't pay for VOLT-AMPS. The difference is in the power factor. For an incandescent lamp, the power factor is 1 and Watts == Volt-amps. For everything else, volt-amps > watts. You pay for watts...at least where I live.
I just plugged a random 13W CFL lamp into a kill a watt. Read 13 Watts and 20 Volt-amps. That matters to the power grid, but until they figure out how to charge you for it, you'll be billed for the 13 watts.
This difference is the basis for the power factor correction scam. They come out and measure amps on something with a high power factor. Then they hook up their magic box and the amps read much lower. What they don't tell you is that the watts is the same and you save nothing on your power bill. I've asked for the demo on some of those stating that we'll be using MY watt meter. They never call back.
Kill a watt can measure both volt-amps and watts. I'm wondering about the crest factor capability. Most older electronics has a high crest factor. I've not bothered to calculate accuracy on those devices.
Ok, so to use a kill a watt, you need to be able to unplug the device. That's hard to do for a water heater...which is likely your most hungry appliance. Ditto for the heater, furnace blower, dishwasher, stove, etc. Doesn't work on 240V stuff like the dryer or 240V window air conditioner.
The cleanest solution is to monitor the thing that determines your electric bill...the meter on the side of the house. Blue Line Innovations makes a wireless gizmo that clamps onto your power meter and reads the rotation of the wheel, or for electronic meters, the blinking led. Doesn't have a lot of resolution, but is fun to watch the display accumulate those pennies. Same device is marketed under other brands. They even have a wireless receiver that hooks to your computer for logging. I find it useful for knowing when I've left something turned on. My attic had 600W of lighting. Showed up clearly on the consumption. But the real solution was to replace the lights with CFL and drop the consumption dramatically.
And with a little math, I can tell exactly how much it costs to take a shower. But I didn't need it to know that shorter showers cost less.
You can measure consumption by timing the rotation of the wheel on your power meter with the device on/off and subtract out the base load. Once you have the consumption, you can use indirect measurements. If you measure the time your water heater runs, you can easily calculate the energy consumed.
I put a flapper on the heater register. Turns on a switch when the heater fan runs. Knowing how much gas the furnace consumes/hour and logging the run-time gives an indirect measurement of something otherwise difficult to measure directly in real time.
My earliest measurements were made with a PalmIII PDA. Just point it at the electronic power meter and it reads the watts consumed and graphs it. Doesn't work on the older wheel meters. I can supply the program to anyone who wants to play with it. It's crude, but written in basic so it can be modified. Mostly undocumented, so not for the faint of heart.
Some power companies are moving toward an online service that tracks usage in real time, or close to it. Microsoft Hohm is trying to do a similar thing.
But, bottom line is that knowing may not help. Telling your kids to take shorter showers will probably work for a week...maybe. Enforcement is the key.
Bottom line: I spent a lot of time tracking energy consumption. After the novelty wore off, I was left with the same guidance I had before I started. Turn down the thermostat, Take shorter showers, Get more insulation, More efficient furnace, Better windows, Dry clothes outside,
But. For the question you asked, go get a kill a watt. ;-)
regenerative braking puts roughly the same amount of energy back in as was required to accellerate the car to speed in the first place, or to take it up the hill if you are coming back down. Not 100%, for sure, but likely better than 75% on today's sophisticated hybrids.
I built it, and yes it did have SOME regenerative braking, but not a whole lot. Full feild it at speed, and it slowed down real quick, but only on full voltage.
Lithiums would definitely have been the cat's meow!!
What happens every time a Conservative business group tries to build a nuclear power plant or hydroelectric dam? I seem to recall a woman drowning Democrat blocking construction of an offshore wind farm because it would spoil his view of the ocean. I'm sure some left field religious group will file suit against a solar power plant because it steals the life energy from The Sun God. Tell me, how do you store the power from a wind or solar power plant in a practical manner for later use or for when there is no wind or sunshine?
Considering the efficiency of an electric motor, I'd say 75% is *way* high. Remember, you lose energy in both directions and you can't recapture it all anyway (or there would be no need for conventional brakes).
All laudable effects, but the electric car devotees are missing the point. The market for a car that only goes 80 miles on a full charge is minuscule.
My vehicle gets more than 250 miles on a tank of gas and I can "recharge" it in five minutes at any of scores of "filling stations" encountered during that 250 miles.
If someone drives 30 miles to work with the lights and A/C on, there's a good chance he won't make it home.
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