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| Confused about PHEV, Hybrids, etc... |
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| gnuarm:
--- Quote from: bdunham7 on August 02, 2022, 02:56:46 am --- --- Quote from: gnuarm on August 01, 2022, 10:31:48 pm ---I don't use the MPGe ratings because they are detached from reality. They are used to try to compare BEVs to ICE, but not in a useful way and clearly with significant variations... ...I have no interest in MPGe numbers because i never use them. Why not calculate using furlongs per fortnight? --- End quote --- Because MPG-E numbers are what is listed on the window sticker, so that's all there is to go on for an apples-to-apples comparison between models. And converting to Wh/mile or kWh/100kM is straightforward enough. 15kWh/100kM is 139.6 MPG-E. Like any EPA ratings, YMMV. --- End quote --- All you need to do is talk to people. It's easy to get good numbers. But I've never cared much about the tiny details. There's too much variation in conditions to worry with be overly accurate. 4 mi/kWh is plenty good enough. Every BEV I've seen will report the remaining charge in both kWh and distance. Is the MPGe rating something linear? How do they calculate it? I assume it has a magic fudge factor? |
| bdunham7:
--- Quote from: gnuarm on August 02, 2022, 05:05:58 am ---Is the MPGe rating something linear? How do they calculate it? I assume it has a magic fudge factor? --- End quote --- It just starts with the fundamental assumption that a gallon of gasoline is 'equivalent' to 33.7kWh. Which it is, provided you have a 100% efficient gasoline powered water heater. One thing about the numbers we've been talking about, including my 239kWh claim for my Focus, is that MPG-E is based on 'at the wall' power--including charging losses--whereas the car will generally report power used from the battery. So that becomes a 'fudge factor' if you will. But still, 139.6MPG-E simply means you drew 15kWh from the grid for every 100kM. |
| tom66:
--- Quote from: gnuarm on August 01, 2022, 09:14:31 pm ---So which BEVs can't attain 15kWh/100km? Mine is one, it gets more like 300 Wh/mi (19 kWh/100 km), but it is an outlier because it is a large luxury car. --- End quote --- Speed dependent (of course), but my PHEV Golf gets about 18kWh/100km on longer trips before engine is used. The e-Golf gets about 15kWh/100km. Even big SUVs like Kona electric can get less than 16kWh/100km (4 miles per kWh) when driven sensibly. At about 120km/h then efficiency falls. e.g. 20-22kWh/100km may be more realistic. The problem with EVs is torque is addictive and if you full throttle it all the time from the lights your battery will not last as long as you expect :o |
| gnuarm:
--- Quote from: bdunham7 on August 02, 2022, 05:38:48 am --- --- Quote from: gnuarm on August 02, 2022, 05:05:58 am ---Is the MPGe rating something linear? How do they calculate it? I assume it has a magic fudge factor? --- End quote --- It just starts with the fundamental assumption that a gallon of gasoline is 'equivalent' to 33.7kWh. Which it is, provided you have a 100% efficient gasoline powered water heater. One thing about the numbers we've been talking about, including my 239kWh claim for my Focus, is that MPG-E is based on 'at the wall' power--including charging losses--whereas the car will generally report power used from the battery. So that becomes a 'fudge factor' if you will. But still, 139.6MPG-E simply means you drew 15kWh from the grid for every 100kM. --- End quote --- I suppose that's useful if you want to calculate the impact to your electric bill. Not much use to determine range or anything else. To me it is a pointless value. |
| gnuarm:
--- Quote from: tom66 on August 02, 2022, 08:53:14 am --- --- Quote from: gnuarm on August 01, 2022, 09:14:31 pm ---So which BEVs can't attain 15kWh/100km? Mine is one, it gets more like 300 Wh/mi (19 kWh/100 km), but it is an outlier because it is a large luxury car. --- End quote --- Speed dependent (of course), but my PHEV Golf gets about 18kWh/100km on longer trips before engine is used. The e-Golf gets about 15kWh/100km. Even big SUVs like Kona electric can get less than 16kWh/100km (4 miles per kWh) when driven sensibly. At about 120km/h then efficiency falls. e.g. 20-22kWh/100km may be more realistic. The problem with EVs is torque is addictive and if you full throttle it all the time from the lights your battery will not last as long as you expect :o --- End quote --- Tires too! You seem to be talking about hybrids. I have no idea how the extra weight of the engine, etc. and the added complexity affects the mileage. I'm rather amazed that they barely beat my tank. Nothing personal, but hybrids are only about reducing cost of fuel. They will never be a zero emissions solution. BEVs may not be zero emissions currently, but as more renewable power comes online, they ultimately will be truly zero emissions. |
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