I have never owned an EV. I’ve driven internal combustion vehicles for the last 40 years, and have never run out of gas. I’ve always been able to make it to a gas station when needed. Sure I’ve come close a few times. But even though people have been driving ICE vehicles for well over a century, people still run out of gas. You see them on the highway. People walking with a gas jug back to their vehicle, so they can get enough fuel to drive to the gas station to fill up.
So what happens in your EV when you run out juice? And don’t say people are more careful and won’t let that happen. It happens and will happen.
Possible answers:
You have to be towed to a charging station
You carry some sort of battery pack, just for this reason, that will get you to a charging station. (if this is the answer, how much do these batteries cost?)
There’s some sort of side reserve built in to the batteries in the vehicle, that only kicks in once you have depleted the main battery.
There has been talk of a diesel generator on a truck that could come and deliver a fast charge. I haven’t seen that it has actually happened though.
Where I drive there are a lot of places I could duck in for an emergency drive if needed, and the car will certain,unwarned you’re that you’re running low.
Maybe car-to-car charging? Not sure if there’s any technological problem with battery-to-battery transfer (speed?), but if you could transfer say 50 miles of charge in a few minutes, Uber drivers could offer the service, and be much cheaper than a tow truck.
While I imagine it’s not that technically difficult to get a portable 240Vac diesel generator on a tow truck capable of charging ~30-40mi/hr or so, I don’t know if it’s particularly cost-efficient to do so just for the low % of EV vehicles on the road, especially given the time that the tow truck would have to sit charging.
Eventually I imagine some form of a mobile supercharger (note the battery pack shown in the link is sufficient for 100 vehicles) may become the norm for roadside assistance vehicles, assuming EV adoption reaches a sizeable share of the market.
Perhaps they can design cars with an internal combustion engine that charges the battery pack, and/or provides propulsion on its own in case the battery is drained. Oh, wait…
Like others said, the answer now is that you get towed.
There’s no reason we can’t eventually have mobile charging setups. A truck with a beefy diesel as its main engine, and a power take-off to a generator, could charge any EV out there at its maximum rate (~250 kW currently, though most are less). 5-10 minutes of charging would be the equivalent of a gas can with a couple of gallons.
If you’re really in trouble, but have another car handy, you can tow the EV with a strap and use regeneration to charge the battery. This actually works remarkably well, and you can get 5+ miles of charge for every one mile of towing. Not too efficient but works if you don’t have alternatives.
It’s not something I’d recommend in general. But it does help that the regen causes a huge amount of drag, so it’ll tend to keep the strap taut and give the follower some extra reaction time. And there’s no need to go very fast; 15-20 mph gives plenty of charge rate.
I find it funny that it’s a bit like those little toy cars with the inertia wheel. You “charge” them by pushing on them to spin up the wheel, and they keep going well after you let go because of the stored energy.
I don’t know if the drag is enough. The way I was taught, the car being towed provides the braking, so that the strap doesn’t go slack at, say, a stop sign. If it is not done this way, there will be a jerk when the tow car moves again.
I think they might already provide such a service? The other day I was behind a van that said “AAA BATTERY CHARGING” or something similar. I was tired and it was late and it took me a minute to figure out why the hell anyone needs a service for re-charging AAA batteries. To be fair to me, the “AAA” on the back of the van wasn’t the AAA logo. That logo was on the side.
Anyway, they seem to have a van ready to go for jumps. I would think they have it set up for EV charging as well, and a map to the nearest station. I have AAA and you have to be fairly specific when you call them for service so I can see them having this scenario already planned out.
Regen is like moderate braking, though. Most days I don’t touch the brake pedal at all in my Tesla (the only exception being catching a yellow light at the wrong time). If the front car is gentle enough (and you’re on flat ground, etc.), and there’s not too great a weight imbalance, they could let the towed car do all the work here.
Looks like they did until recently, at least in some areas. The article isn’t super clear as to why it didn’t work out. AAA says they’ll have a different version in the future but for now they just tow. Maybe running out of juice is just so uncommon that a special charging fleet isn’t worth it.
The EV’s I’ve researched all deliberately mis-report your charge status to keep you from repeatedly discharging the battery down to zero, because that’s very bad for the lithium batteries. Also, repeatedly charging them up to maximum is bad, too, but that’s not much help here because it’ll always say you’re at full charge once you’re done charging, even though it’s only at 85% of true maximum. When it says it’s at zero charge, most EV’s will still have 10-15% of (true) maximum charge remaining, which will be 20-30 miles these days. You may need to go into the vehicle setup and manually override the default limit so you can use that last few miles, though.
True max/min for Li-ion is blocked out as you would quickly destroy the battery if you got to them, I doubt there would be any such override to get to true zero. There may be a false floor that is overridable, but it is not true zero. I’ve never heard of it and also saw what happens when EV’s run out of juice, like your cellphone they shut down. One type, perhaps very early Tesla’s, could not be simply recharged after and needed some different procedure to get it going again IIRC.
It wouldn’t surprise me if the generator thing happens eventually. EVs are still rare enough that not many people are going to invest in infrastructure just to deal with this problem. It’s not like a tow truck carrying around a few gallons of gas knowing they’ll probably use it in the next week or so.
As for swapping batteries, as it stands, that’s not an option. Replacing the battery on a Tesla involves removing the entire body. In this picture, it’s the big, flat, metal/silver/shiny thing in the middle of the frame. It’s literally the size of the car.
On the one hand, it wouldn’t surprise me if they did come up with a way to attach an accessory battery (like a forklift battery) to the vehicle, toss the battery in the trunk and have enough juice to get the car a few miles down the road. Sort of the equivalent of bringing someone a few gallons of gas.
On the other hand, a Tesla is working with nearly 400DCV. That’s not something to mess with. The few videos I’ve seen involving batteries have people working on them like they’re working on high voltage transmission lines with big rubber gloves and insulated tools.
For such a thing to be possible/easy/safe for the random tow truck driver, Tesla would have to build in this ability. I’d imagine a port, not connected to anything where they could plug in, then flip a switch to disconnect the main battery and connect to this one.
I’m sure something will get figured out because people will get stranded, but it’s going to have to be a bigger problem first.
