An Electric Car for TEOTWAWKI? – Part 2, by S.B.

(Continued from Part 1.)

Using the AC/Heater in the Car Matters (a lot)

The weather is not only going to have more of an affect on your electric car (compared to a gasoline vehicle), but it is going to have more of an effect on you because using climate control draws a lot of juice from your battery. In a gas vehicle, running the heater has little to no effect on the vehicle’s performance because you are just pulling heat from the engine compartment that is a byproduct of the engine running. Although running the air conditioner (AC) in a gas vehicle is supposed to reduce the miles per gallon (mpg) you achieve, I have never noticed much of a difference in the myriad cars I have driven over my life. However, in an electric car, the same battery that powers the engine also powers the heating and AC. In my car, if I turn on the heater or AC, the travel range on the display immediately drops about 15%. So, all else being equal, if I have enough battery charge to take me 50-miles, if I have my AC or heater on during that trip, I’ll only get about 43-miles. Not long after I first bought my car, I noticed that it had seat heaters. I thought that was a pretty luxurious amenity for such a basic vehicle. Then I figured out that it takes a lot less energy to run the seat heaters than to run the heating elements that heat the air in the cabin. The seat heaters weren’t an amenity, they were a workaround to minimize the need to use the “regular” heater.

For me, this plays directly into the charging time issue discussed above. When I commute to work, by the time I get to the parking lot, I don’t have enough charge to get back home. Fortunately, I have access to a Level 2 charger at the office. Still, every day, there is roughly a 3–4-hour period where if there was an emergency, I could not use my electric car to get home. So, to minimize this “can’t make it home” window, I use the heater very sparingly on the way into work. On winter mornings, I’ll be driving down the highway with gloves, scarf, and ski hat, rag in hand wiping the condensation from the cabin side of the windshield. Only when the condensation gets too bad will I treat myself to a few minutes of running the defrost. With the long charge times for electric vehicles, everything takes planning, because there is no stopping for gas whenever you need it.

If you go anywhere that takes more than 50% of your charge, expect to spend some time at a charger before heading home. In reality, and particularly in a TEOTWAWKI scenario, going anywhere that takes up to 30% or 40% of your charge under ideal conditions should include charging up time at the destination. What if the you-know-what has hit the fan? Say I’m driving with a couple of people from our retreat to the trader fair. We are toughing it out on a cold day, staying bundled up in the electric vehicle so we don’t need to use battery for the heater. It takes 45% of the charge to get to our destination. One of our group gets seriously injured and the best venue for treatment is our retreat. We need to turn on the heater to keep our injured teammate from going into shock. We-are-not-making-it-home-in-that-vehicle. Similar scenario but needing the AC instead. We-are-not-making-it-home-in-that-vehicle.

Elevation Change Matters

Every vehicle uses less fuel going downhill than uphill. It’s just physics. If you use half a tank in your gasoline vehicle to go down the mountain, your remaining half a tank won’t be enough to get you back up. However, the disparity between downhill mileage/range and uphill mileage/range is even greater in an electric vehicle because you aren’t just using less fuel coasting downhill, you are creating fuel. All modern electric vehicles have a generator system that kicks in when you coast or apply the brakes. When you go down a hill, you are generating power that extends how far you can go. On my commute to work there is a grade that drops about 1,400 feet over only about 1.5 miles. When I go down that grade, I in effect add almost 1% to the battery capacity, or roughly ½ to ¾ mile of extra range on the flatland. If your trip is taking you downhill, this can create a false sense of how much charge you actually need to get back up the hill. You take a trip with a 2,000-foot drop in elevation. At your destination you have 60% of the charge left on your battery. Must be enough to get back home. Right? Well, unfortunately, no. It’s going to take a lot more energy to get back up the hill than it took to get back down because not only are you fighting the physics of going uphill, but you aren’t making any energy on this leg of the trip. You are getting hit by a double-whammy and you aren’t making it home in that vehicle. The other side of that coin is, if the first leg of your trip is uphill, you might only need 45% charge or less to be able to make the downhill portion of the round trip.

Speed Matters

For those of us old enough to remember the 1970s, you will recall 55-mile per an hour speed limits on the interstate highway system to save fuel during the OPEC oil embargo. For you readers not old enough to remember the 1970s, don’t worry, it’s looking like the Biden administration is doing all it can to create the seemingly oxymoronic malaise and mayhem of that bygone era. But I digress. The point is, pushing a vehicle at higher speeds reduces fuel efficiency. I don’t know if the electric vehicle platform is more susceptible to this law of physics, or if it is just because I’m driving a car where a “full tank” is equivalent to about a quarter tank on any normal gas-powered car and I can detect smaller changes in fuel efficiency, but going fast sucks more juice out of the battery. If I drive home from work averaging 70 mph on the freeway, I have significantly less charge left when I get home than if I average 60 mph. I can’t verify this, but I have been told that the sweet spot on most electric vehicles to travel the most distance on the least charge is 45 mph. What I can verify is something we know from NASCAR, bicycle racing, and other sports…drafting does work. If I do a chunk of my commute behind a semi-truck, delivery van, or even a large pick-up truck, even at safe following distances, my vehicle uses less fuel.

So, thinking through another hypothetical TEOTWAWKI scenario, I’m out patrolling my neck of the woods at reasonable, cautious speeds. I take my vehicle to 50% charge. Then, just as I’m about to turn around for home, I make contact with a hostile force. My best move is to drive as fast as I can back to my retreat. However, driving at maximum speed, I’m now using a lot more charge and that vehicle can’t take me all the way back to my starting point. I’m either trying to get the rest of the way to my retreat on foot, or using what is now my 4-wheeled hunk of inert metal as cover/concealment for a fight.

This limitation may be equally true for a gasoline vehicle. So, if times are truly bad and you are making any movements in a vehicle, plan accordingly.

(To be concluded tomorrow, in Part 3.)


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