EV Fundamentals: Range Killers
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Range Killers
04.21
| 00:00 | One of the biggest talking points and probably the most rapid area of improvement when it comes to electric vehicles is range. |
| 00:05 | This is something that we briefly discussed in the earlier EV overview module. |
| 00:09 | And now it's time to delve a little bit deeper into this subject and why increasing the range of electric vehicles is such a challenge and how it's affected by different variables, some controllable and some not. |
| 00:21 | Just a few years ago, the only practical application that many saw for consumer EVs was inner city runabouts. |
| 00:27 | And that was due to the woefully limited range available. |
| 00:29 | These small, low battery capacity vehicles are still out there and still being sold and they're definitely fit for purpose. |
| 00:35 | But battery and management tech has come a long way in a very short amount of time. |
| 00:39 | And that means we're now seeing OEM vehicles with ranges comparable to traditional and sometimes in excess of traditional combustion powered offerings. |
| 00:47 | As we touched on earlier, due to the nature of an EV system when compared to ICE, our vehicle carries substantially less energy on board. |
| 00:55 | And for that reason, everything about the car needs to be much more efficient and optimized in order to get any kind of decent range. |
| 01:01 | This is why early attempts like GM's EV1 in the late 90s, for example, looked like a melted block of butter on skinny tires. |
| 01:08 | Engineers were doing all they possibly could to make the car as slippery and friction free as possible in order to get anywhere near a range that consumers would be okay with. |
| 01:18 | So, yes, while the tech has come a long way since those days, factors like friction and aerodynamic drag still prove to be range killers on an EV system. |
| 01:27 | This applies to all electric vehicles, but is an especially important factor in electric converted projects because we're often physically limited in how big of a battery system we can fit. |
| 01:37 | Also very relevant to swap projects is the fact that if we decide to run a motor through an OEM transmission and then an OEM diff, turning the power 90 degrees, we'll significantly reduce the range when compared to an EV specific drive unit, which generally has a single gear reduction. |
| 01:52 | This is just the same principle as the driveline losses we see when comparing a traditional gasoline vehicle at the crank power figures versus at the wheels. |
| 02:00 | Only all that friction has a far greater impact on an electric system's range. |
| 02:05 | Large, sticky tires are another big source of friction that affect a car's efficiency. |
| 02:09 | To be clear, this isn't like the nominal difference that we'd probably never notice in an ICE vehicle when upgrading wheel and tire package. |
| 02:16 | But as a general rule, a big set of rubber on an EV will increase the power required to drive down the highway by about 15 to 25% versus smaller eco tires. |
| 02:25 | Aerodynamically, there are ways of clawing that back. |
| 02:28 | The best example is a flat floor that ensures the air can pass smoothly under the vehicle, as well as channeling air around the wheels and tires and not hitting it head on. |
| 02:38 | Something that nearly all modern electric vehicles employ. |
| 02:41 | This is going to net an increase of 10 or 20% in range at highway speeds. |
| 02:46 | Now, obviously, that figure changes exponentially based on speed, but it gives us some indication as to how sensitive EVs are to these kinds of factors. |
| 02:53 | The final big range killer is our ancillaries. |
| 02:56 | Let's take a typical fairly efficient EV. |
| 02:58 | It's going to require about 15 kilowatts of power to cruise at 100 kilometers an hour. |
| 03:03 | Anytime you add an additional load to that, you can easily figure out how much your power draw will change accordingly. |
| 03:10 | For example, a poorly insulated cabin using resistive heat in the winter will require 5 to 8 kilowatts of heat through a PTC, positive temperature coefficient heater. |
| 03:21 | As there's no combustion engine to use as a source of free heat. |
| 03:25 | So, that increases the required power to 20 to 23 kilowatts at 100 kilometers an hour, and that works out to about a 45% increase in consumed energy. |
| 03:35 | On the flip side, in the summer, a high voltage AC compressor will use maybe 3 to 6 kilowatts depending on the load. |
| 03:41 | Obviously, I'm not suggesting we should just put up with being too cold or too hot, nor should we be playing at the fiberglass and mocking up homebrewed aero enhancements. |
| 03:49 | And we can definitely leave the space saver wheels at the wreckers. |
| 03:52 | But these range killers are all something that need to be kept in mind and a healthy compromise found if you're planning on your own EV conversion project. |
| 03:59 | In this module, we learned that EVs carry far less energy on board when compared to ICE power vehicles. |
| 04:04 | This means that factors like tire friction, aerodynamic drag, and ancillary equipment usage all have a big impact on range. |
| 04:11 | So, the more we can minimize and optimize those sources of power waste, the more we'll be able to do with the limited amount of energy available to us. |
