# 2018 Nissan Leaf - Recharge time

Several times you have spoken favorably about electric cars. While I am certain they have their place as city commuters, I believe they will never become a family’s main transportation. The reason is the lack of a “quick” recharge. Stopping for several hours during a trip is not something “built in” to most Americans. People will demand a recharge time similar to a typical fuel stop, or about six minutes. Longer range batteries are now 100 Kwh and above. You can do the math for pumping 100 Kwh into a battery in 6 minutes, as I have done and come up with one megawatt/hr power flow for six minutes, not counting any frictional losses. Even if the battery to do this is developed, I can’t imagine municipal power supplies being able to recharge more than a couple of cars at the same without blacking out the whole town. No one seems to thinking about the municipal power supply quick recharge barrier.

(The car selected below was just to fill the required squares for this submission)

I agree, but I am not Ray. I am a CarTalk forum member.

Just where would there be “friction” be in electrical current? There are losses, for sure but it isn’t friction.

But you are rather perceptive. Assuming the battery could even accept one megawatt without destroying it, imagine the size of the power cables you’d need to use! BTW, the math doesn’t work as simply as you calculated. Li-Ion car batteries don’t like to be completely drained, they don’t want to be pulled below about 40% state of charge. So you are filling 60 kWh and not even 100% of that given how batteries actually accept charge. Assume 80% of the 60% or 54 kWh max. Charger efficiency of 80% and battery charge efficiency of 90% means you need or 0.750 MW in 6 minutes. Still a big number.

But that is only needed on a long trip. A 100 kWh battery will give roughly 300 miles range. More than enough driving distance in a day. Even for soccer practice, band practice and errands. Plenty for their “main” transportation but not enough for the family vacation. That can be solved by renting a gasoline car, flying, or planning the long stops needed to recharge the battery. In many areas, however, there isn’t nearly enough electrical capacity to charge all these cars at night.

Thank you for the interest. Perhaps resistance/heat would be better terms for electricity. I would not expect current batteries or chargers to meet the challenges needed for fast recharge so present limitations on Li-Ion batteries would likely not apply. The big challenge is to the grid, chargers, and electrical connections needed for high rate power transmission assuming that batteries up to the job can be developed. EVs, at their present level of technology will not become main family transportation. If the dreamers get their wish and EVs take over, manufacturers will stop making combustion engine vehicles and with that, the gas station network will wither away making the renting of a gas buggy for a long trip an impossibility.

This is a post that appeals to the engineer in me. Whenever I hear BS about “XX Company will charge your 300-mile range EV battery in 3 minutes” I am certain the person who re-wrote the press release has no clue about energy or any sort of technical training. You would need a cord as thick as a firehose and bringing that power to anyplace other than a municipal lot would cost the owner of the charger a mint since that much juice is not just a quick trench and backfill type job. Another thing the EVangelist always forget is that the battery is never back to 100%. Electrochemistry doesn’t like that last 20% at high rates of recharge. As everyone with an EV knows, the primary re-charge location is always one’s home. And in anyplace with real winter and snow, that means inside a garage. Which means a huge percentage of the population is not really ever going to own an EV. ps - I love the new Leaf. Great around town runabout for folks with \$26K to burn on a second car. Here’s my review.

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Don’t believe the hype that most publications print about electric cars. They generally aren’t engineers (I am, and @GoremJ is) and they have no real understanding of all the dominos that must fall into place to make EV’s function in modern society nor the science behind it.

EV’s have been around for over 100 years. They didn’t win the marketing battle with IC engines 90 years ago for various reasons. Those reasons have dwindled, but they aren’t all solved.

One solution that has not been mentioned is replaceable battery packs. Exchange your battery pack for one fully charged. The station can then recharge the old one slowly.

Has many problems and not practical today, but something to think about.

I proposed that scheme on this site maybe 8 years ago. Universal pack form factor and quick change design. Then set up like the Blue Rhino propane guys. You never own a pack, you rent them from Red Hot Electron. Locate the nearest exchange location and they swap out in minutes. On your way. Plus, pack bums out or has diminished range? No biggie, it’s not yours. Just exchange for new one.

The Tesla supercharger will recharge an 85 kWh battery in 75 minutes. That’s a lunch stop or dinner stop, and provides about 265 miles of range. In another couple of battery generations, electric cars will be reasonable choices for just about anyone. You seem to think that technology won’t improve, but look at the improvement from Prius to Chevrolet Volt. The newer battery technology in the Volt allows for more than twice the full electric range. Then there is the all electric Bolt with about 240 miles range, and the MSRP is about \$40,000, far les than the Model 3 Tesla available today at over \$60,000.

There’s lots of electric cars on the road here in San Jose. Many of my neighbors have them parked in their driveway. I don’t own one myself, but from what I can tell the owners charge them while they are at work, or they charge them overnight, at home, with their home charging equipment. Many parking lots in shopping centers provide free 2 hours charging. I don’t understand how that’s paid for, but such a thing is pretty common. And those spaces are in much demand. The electric owners all seem to have second and third vehicles which are internal combustion powered for longer and out of town trips. For those w/pick-up trucks, most of them are internal combustion. But the vehicle they universally drive the most often, back and forth to work, to the shopping mall, to the soccer matches, to the movies, to the library etc is their electric.

I’m a fleet mechanic and a public servant

I believe it will be awhile before ev technology has progressed to the point where it will be sufficient for vocational vehicles. Many of our vehicles are class 7 and 8, to put things in perspective. Sure, a Nissan Leaf could take the place of a Chevy Cobalt, but what’s going to take the place of a class 8 vehicle with a GVWR of well over 50,000lbs . . . ?!

I don’t see the popularity of electric cars so much as “dreamers getting their wish” but simple economics. Electric motors with similar performance to a gasoline motor are just simpler to design and build than the gasoline version. The challenge at this point for electrics is keeping the battery charged, but most owners have figured out a way to do that for their daily driver. As electrics continue to gain market share the demand for charging technology and charging stations will outpace the demand for gasoline & gasoline stations, and what the OP says is true, eventually there won’t be as many gasoline stations. Just like there are few places to fill up your dirigible now. Or to buy a buggy whip. But I don’t expect gasoline powered vehicles are going away any time soon. At this point the electric/gasoline decision based on purchase price, fuel charges, and repair/maintenance costs seems more like a break even, and that’s for the lower priced econobox electrics.

Two major challenges- charging time as has been mentioned, and battery COST. The cost is still huge, and the materials needed are getting in short supply, cobalt especially.

I think a ‘regular ‘ hybrid is actually the sweet spot in terms of cost vs benefit. No \$30,000 battery pack needed.

I think the realities of the cold weather parts of the country have been ignored, range drops with temp, also with winter tires, also with snow on the road. Then there is the matter of keeping the occupants from freezing to death in a blizzard if stuck for a day or two. No pure electric in my future.

Someone mentioned load capacity for class 8 trucks. My legal gross limit pulling twin 45 foot trailers on the NY Thruway and Mass Pike was 143,000 pounds. Some goodly hills too. I can’t see trucking companies payong drivers to wait for recharging.

Are there any battery electric buses in your fleet, @db4690? If so, how are they charged?

There is a new lithium battery chemistry that doesn’t use cobalt. Lithium-ferro-phosphate.
This battery chemistry has the good fortune of having 3.2 volts per cell which means a four cell battery closely matches the voltage of a six cell 12 volt lead-acid battery and can be substituted for a lead acid battery in cars and motorcycles with a considerable weight savings. A boon for weight sensitive vehicles like off road motorcycles, aircraft, and race cars.
This chemistry is also safer, less likely to result in a battery fire.

Edit: Well, maybe not aircraft, everything on an airplane has to be certified.

the buses are serviced by metro, and I work for the city fleet

But metro does have some electric buses . . . and the company is Chinese . . . and there were very interesting articles written in the Los Angeles times about the profound lack of range and performance

The article did mention, though, that because the technology is still advancing, that the next generation(s) of electric buses might be reliable enough for regular use on more mainstream routes

I have thought about it and it doesn’t appeal to me for at least one reason. I drive my brand new EV until low on juice and roll into the battery exchange station and the fully charged battery I get is five years old and has already lost some capacity. The recharge station recharges MY discharged battery and someone else gets MY brand new battery.

Battery exchange was done…in 1905 or so in NYC. Before many folks owned cars, and when electrics were popular, electric taxis were common, perfect for NYC as long as they could swap their lead-acid batteries frequently.

Now, I see no chance of this. Technology is advancing too fast, no companies would want to lock theirs to a standard, and the battery costs are huge. Tesla claimed they were going to do this, nothing came of it. Another company from Israel claimed they were going to do it, they went bankrupt.

If a city wants to have a electric bus fleet, perhaps it should bypass batteries altogether and invest in a overhead trolley wire infrastructure, like Salt Lake City’s “Trax” light rail system uses.
The buses could still have a small battery for route gaps that are off the grid.

For sure, I think it is a tough sell but not impossible. First of all, if a company can develop a viable business model, they can benefit the car company in a couple of ways. One, the car is delivered with a rented pack already installed. The entire cost of the battery pack is removed from the sale price (and mfr costs to build) giving them a HUGE advantage over the competitor that requires a buyer to pay up front for a multi-kilobuck battery pack. The car mfr does not have to warranty the pack- another potentially huge risk removal for them.

As far a technical risk, batteries are unlikely to ever get larger. So a common form factor now will likely only shrink over time and will remain viable. If they design the charger as a modular part that can be swapped out, they could fairly easily support new battery technologies as they evolve. Even better if it is completely software based…