Just curious. The thread about the I-95 jam mentions in passing that EVs may not handle cold well and run out of charge.
I’m going to drive to work in an hour in -36C, in my gas powered vehicle. How would an EV handle temperature? Same as gas-vehicle? Worse? Better?
And a follow-up question - if an EV runs out of charge because of major traffic delays, how can it get re-charged? If a gas vehicle runs out of gas, an emergency service can bring some gas to get it going again. Is there an equivalent emergency charge option for EVs?
Cold reduces the range of EV’s. As this is due to the physics involved even if improvements can be made the problem can not be entirely eliminated.
Nope. If your EV runs out of juice it has to be towed.
I don’t know if the future will result in some alternative, but at present that’s where we are.
The future is now. Here’s one such alternative. How widespread such solutions are is a different question. And they’re not as easy as a can of gasoline. But a blanket “it has to be towed” is false.
My wife has a plugin hybrid (Ford C-Max) and in cold weather it gets about 10 miles on a full charge before the gas engine kicks in. That’s about half of what it gets in warmer weather. Funny, I always chalked it up to having the heater and defroster running (which I assumed were electric) plus the heated seats. I never really thought about it being because the battery itself wasn’t holding a charge as well in the cold.
OK, good - next questions:
How long does it take to charge vehicles sufficiently to get to a non-mobile power station? (I’m assuming it would be more efficient in a jam like on I-95 recently to not fully charge the stalled vehicles, just give them enough to get to another station, like using a 5 gallon can of gas to get an ICE vehicle to a service station).
How many of these would be needed to clear a jam like on I-95?
I’ll amend my answer to it’s probably, at this point, more efficient to tow the vast majority of these vehicles than to try to re-charge them in place. But that could change in the future.
And those are perfectly valid questions we’re a long way away from (and might never be able to get to) answering in a way that doesn’t imply that events like this are a much larger problem for electric vehicles than for ICE vehicles.
I read about one mobile recharging system (there are many obviously) that could provide about a mile of range per minute of charging. The typical situation is that you’re perhaps five or ten miles short of home or a supercharging station when the batteries run out, so it’s not infeasible to spend half-an-hour recharging a typical car. The situation in Virginia is extraordinary and not just for EVs. If AAA were providing five-gallon cans of gas to refuel the ICE cars on that road, they’d need a whole bunch of them.
I’ll also point out that there are instances where authorities will use tow trucks to clear ICE vehicles from a traffic jam rather than attempt to refuel them one by one. Circumstances vary, and options are good.
Exactly - that’s an instance where tow trucks may be employed either to get the ICE’s to a refueling point or just move them to where owners can access them more easily with a 5 gallon can of gas without said vehicle obstructing traffic.
Regarding general performance in extreme cold weather, a Tesla owner in Saskatoon has done a Q&A thread on the Saskatoon subreddit. I can dig up the link if you’re interested. The general takeaway is 40-50% range loss at sub -30 temps. You really want to be plugged into a charger when not in use so it can use grid power to keep the batteries warm, rather than using battery charge for that purpose. Cabin heats up quick and easy, no waiting like in an ICE vehicle.
That said, regarding cabin heat I saw a story just today about some Tesla owners in Alberta experiencing cabin heating issues apparently stemming from a software update over the past couple days. That is not a sort of glitch I’d be at all happy about. Still, cabin heat for EVs generally ought to be more reliable than in ICE vehicles, at the cost of additional range loss of course because the energy comes out of the battery charge instead of “waste” heat.
At -37 this morning, I feel it important to put scare quotes around “waste” in reference to heat. 
As EVs increase market share, we may find that tow truck operators who ordinarily bring a couple of gallons of gas for ICE vehicles will be fitted with an on-board genset that can give a flattened EV battery enough energy to get them home. However, it might require a pretty big genset to quickly provide even 30-40 miles of range. Maybe better to have a battery with an inverter that can provide AC power to the dead car. A tow truck that is itself an EV would make for a very clean solution to all of this.
Yeah, most portable generators can generate 30 - 40 amps at 240V via the one plug they have. It would have to be a pretty customized/specialized one to be able to deliver more than that. At that low of a load, it would take quite a while to get a reasonable amount of range.
It also depends on the charging capacity of your vehicle, as many of the older ones are not capable of taking “quick” charges at high amps/voltgage.
If you were designing a genset for a towtruck, you’d use the towtruck’s engine to power it directly. You’d potentially be able to deliver a couple hundred kilowatts - 200kW = 268HP. I’d think most towtrucks have engines with power well in excess of that. Drive a bigass winding around inside a bigass magnet and Bob’s your uncle. You’d obviously want big beefy electronics to control the output and match most common fast charge standards.
It wouldn’t be particularly cheap, but there’s nothing technically challenging about making such a thing. If there’s a market for such a service, there’ll be someone providing it.
Yes, but …
Re-directing engine power (normally sent to the transmission) to a generator implies a serious increase in mechanical complexity. This would be a low-volume mod, and thus (as you note) expensive. The charge delivered would need to be enough that the EV can reach a charge point with some excess of range.
I suspect any careful analysis would lead to the conclusion that in nearly all cases the sensible choice is towing the EV to a charging station.
It’s just a power take-off transmission. Tow trucks already have PTO transmissions to drive their winches and hydraulic pumps. The expensive part would be the power regulation and fast-charge format-matching.
luckily 24 hr traffic jams are exceedingly rare because it all goes to $#!t in that scenario.
Even if there’s a Setec van that naita linked to & there’s a charging station just one mile up the road. The van gives a little juice to two EVs at a time (best case scenario) they drive off to hit the nearby recharge station, except they sit there for 20+ mins taking on electrons. Cars 3 & 4 are waiting for 1 & 2 to charge & drive off before they can plug in. If you’re 10, 20, more cars back in that traffic jam you’ll probably run out of juice again just waiting in the line to plug in.
Would a typical PTO handle 268 hp?
EVs don’t use a lot of juice just sitting there. In fact, they tend to be more efficient the slower you go (to a point). Cold is going to change the picture somewhat since you have the heater running, but newer EVs generally have efficient heat pumps. A long range EV can sit in traffic for many hours, possibly days, before running out of juice.
As for the tow trucks, another method would be to tow while the car is on, and make sure regeneration is at the highest level. You could potentially generate something like 5 miles of charge for every mile of towing, so the truck wouldn’t have to go all the way to the charging station.
Looking at Muncie’s product lineup it looks to me like a typical existing tow truck PTO is probably rated in the 60-90HP range, so not quite. But it’s not like it would be difficult or vastly more expensive to engineer one to handle more power. PTOs on agricultural tractors can handle a lot more power than that, for instance.
That said, this is the beefiest PTO Muncie shows in its tow products, and at 95HP it can provide a theoretical 70kW charging rate, minus losses to generator efficiency and power regulation, which should already get 10-20 miles of range into a dead battery in just a few minutes.
I just want to challenge the (unstated) assumption that an EV is more likely than an ICE to run out of juice in this scenario. An EV battery is capable of heating cabin air (as well as heated seats, radio, etc.) continuously for days, not hours. My EV has a 62 kWh battery which would be enough to run my entire house (including heating) for about 2 days. I would expect in an extended traffic jam situation where the battery has nothing to do except run the heating and entertainment, I would run down the battery at about 1% to 2% per hour. Meanwhile the ICE cars are running down their fuel at maybe 1/4 to 1/2 gallon per hour idling their engines to heat the cabin.
So before asking about towing or recharging, consider that the EV is probably better equipped than a fossil fuel vehicle to cope with this extended traffic jam scenario, and more likely to be driving away without needing assistance once the road is clear.