Series hybrids : they make paper sense, why aren't they more common

On paper, leaked numbers show that Bolt’s battery costs GM $145/kWh for the bare cells. Or $8700. Let’s round up to $175/kwh to factor in the cost of all the circuitry and structure around the battery. So the battery probably costs GM about $10,500 per car they produce. (they probably lose money on the vehicle).

60 kWh is 230 miles of electric range. Almost no one drives that daily. Instead, how about you put a battery in that gets you only 100 miles of electric range, or about 30 kWh. So the battery only costs the manufacturer $5,250. Then you put a conventional engine/generator. It would be a motorcycle engine, since they are cheap and mass market, tuned for enough power output to match the energy needed to keep the car moving at highway speeds while at design load. Basically a “sustainer engine”. A small fuel tank (2-5 gallons), and you run the engine at wide open throttle at a fixed RPM when it needs to run. Power to accelerate comes from the batteries.

So it would be intended as a car that nearly all trips are done on pure battery power (since it has a little more range than a Leaf) but long car trips are possible using the engine. It would also be cheaper, a conventional engine/generator is probably less than $5250 per unit for the manufacturer.

So what’s the drawback? I keep thinking about how much sense it makes - basically you don’t need the ability to supercharge or to wait at rapid chargers, but almost never have to pay for gas. As the battery pack ages, the lost range doesn’t matter as much since you still have an engine.

At the risk of sounding snarky, the drawback is clear.

The great bulk of American people simply won’t buy electric cars that don’t go 200-plus miles on the battery. Because they’re stupid and they can only think in terms of one power source and one fill-up.

The extra $5K in batteries is (as you say) engineering and economically stupid. But it’s marketing essential. And marketing wins every time.

20 years from now when a new generation of consumers has been raised on vehicles that have two power sources, a plug-in and a gas tank, the problem will go away. Except for Buick, which will need to be making 300 mile gasoline-only cars until the very last Baby Boomer is dead and buried.

Have you literally never heard of the Chevy Volt?

I’m not even going to ask if you’ve heard of the BMW i3 or Toyota Prius Prime.

I knew about the BMW i3. I was asking why they aren’t more common. The other 2 cars you mention are parallel hybrids with miniscule batteries.

That reply (meaning my reply) was too snarky. Let me rephrase: there are several cars like this on the market, but I think generally either many people don’t understand them or they don’t want to pay the extra money over a traditional hybrid.

You start making it hard to sell those cars in cold weather climates. Range can be reduced by 50% or more when you take into account effects like drawing power from cold cells, cabin heating,etc. (Cite)

For a lot of people in cold climates that becomes what we already think of as a hybrid since the engine has to run so often. It’s kind of a crappy hybrid too. The engine has to kick in early because it can’t provide the maximum power that might be called on.

This still seems like a good idea. Even better in colder climates than all-electric. It means you won’t get stuck somewhere and freeze to death, having gasoline power on tap. And yes, you get less battery range, but so? It would make most cold weather commutes as well just fine.

Note that the purpose of this car is for someone who lives somewhere and commutes a practical distance to work. (no more than an hour each way). Someone who is driving hours each day most days of the week needs a parallel hybrid.

There are multiple problems with your assertions, both in terminology and in the criteria you use. The Chevy Volt is not truly a “parallel hybrid” – that would be more like a conventional hybrid like a Prius or a hybrid city bus. It has a complicated transmission that does include a mechanical linkage to the ICE but it’s only used in certain of the extended-range modes. It has both a large traction motor and a small motor/generator and that, plus the ICE, are used in various combinations in various circumstances, but the significant thing about the Volt is that by and large with charged batteries the Volt does most of its driving in full EV mode.

If someone is looking for the kind of thing you describe as a “series hybrid”, something like the Volt is it. You want a range of 100 miles. The Volt can do 53 before the ICE has to cut in. If someone wants more than that on all-electric power, they can opt for the all-electric Bolt at 238 miles. It’s not clear what you’re complaining about since both sides of the continuum are covered.

Why have a battery large enough to go 100 miles? Most drivers in America drive on average under 30 miles/day. The 50 mile all-electric range of the current Volt’s “miniscule” battery provides for most drivers daily needs most of the time. Heck many drivers could do most days’ driving on all-electric with much less range. My smaller C-Max range gets me to and from work most days without using any gas, for example. At least when its not too cold … turn on the heat and the engine will come on, and yes range drops. (Still in regular hybrid mode I get mid 40s mpg and it is a nice driving car.)

The Volt was initially billed as a series hybrid and did work in that fashion lots of the time (never was a pure series hybrid though). As it’s evolved they’ve move away from that model to a more parallel hybrid system when not on all-electric. It is just more efficient.

What’s the potential attraction of all electric? No engine to maintain or to wear down. The downside of course is that initial battery cost and the specter of having to replace it. Prices are coming down. (Estimates were $1000/kWh seven years ago, now $175!?) Real data on battery longevity is still sparse but they seem to be durable anecdotally anyway.

Tesla seems to lose 23 miles of range per 100K driven.. So by 300K the base Tesla 3 (215 mile estimated range) will be be down to a 146 mile range. Still a satisfactory commuter. Even in cold weather.

Right. Terrible design. A completely separate and inexpensive engine module makes a lot more sense.

Again, the issue is marketing. Most Americans [del]think[/del] fervently believe they *need *one car that can do it all: drive 2 miles to the grocery store, 40 miles to work, and 2500 miles on summer vacation. In rain or shine, roasting hot, mild, or bitter frigid cold. With no more than a 5 minute stop to upload more fuel/power.

It’s a slow process to re-educate the masses to think differently about what they’re really buying: transportation services, not a car. Right now all the various specialized forms of transportation services are small niche markets. Whether that’s a rental pickup truck from Home Depot, a ride from Uber, a zipcar, or a self-owned series or parallel hybrid or even a pure plug-in.

The public is very, very slowly starting to learn more and to think more flexibly. The challenge for a marketer is to be out ahead of the public enough to *gently *tug their reins in a useful direction. But not too far out in front, lest the public simply dig in their heels, ignore the reins and you’ll watch as your product goes utterly unsold.

So you claim. But I’ve yet to read you make any reasonable arguments why. The first step is to prove that an inexpensive engine charging the battery which then converts into kinetic energy (losing some efficiency at each step) is not less efficient that an engine system that variably directly powers the wheels and the batteries keeping at near optimal efficiency output at all times. Then you have to be sure that the inexpensive engine is big enough to keep up with the power needs (after conversion into the battery and out) at all times.

FWIW the one true series plug-in hybrid on the market currently: the BMW i3 REx goes pure electric for about 81 miles and then the ICE kicks in to charge the battery and only that getting its total range to about 150.

Of course there have been reputed real world problems with its ICE being able to provide enough power to replenish the battery fast enough, enough to provokea lawsuit.

Costs quite a bit more than the Volt. Few days most drivers need more range than the Volt can provide on all-electric but on those days the Volt can relatively drive all day (370 on in pure hybrid mode after out of the 50 miles pure BEV range) as a regular hybrid performing at its usual impressive levels. The i3 REx? Will allow you to relatively hobble to a charge point.

So why not more of them? Because who wants to buy a product that has inferior performance overall for significantly more money?

Be careful on the whole range thing. Driving a lot of steep hills or a good Minnesota winter will greatly reduce that range.

There are also some weird legal bits. For instance, the BMW i3 REx has a software limited gas tank. That is, the gas tank holds gas that the ECU won’t let you use.

The reason for this is that in CA, you get special treatment if the range extender has less range than the battery. So, if you have an 80-mile battery and a 79-mile gas tank you’re cool; if the tank is 81 miles, you’re treated no better than a conventional hybrid.

So the i3 limits the gas extension range artificially so they get the better treatment. But this has a side effect of making the car much less practical than it could be.

because there’s no inherent advantage to a series hybrid over a parallel hybrid. The Volt and i3 are about as close to a series hybrid as exists, and even they still mechanically couple the engine to the output drive when it’s more efficient to do so. (edit: apparently not so with the i3)

why geeks have this hang-up about “pure” series hybrids is beyond me. In the real world, “purity” takes a back seat to reality.

ok. where’s yours, then?

FWIW update on the one true series plug-n hybrid, the BMW i3 REx - 2017’s has a denser battery so electric range is now rated at 114 miles per charge which has let them “unlock” its full 2.4 gallon tank which should allow for another 80 to 85 miles using the little ICE to keep the charge up enough (195ish miles from full battery and tank to out of power).

Still priced higher than the Volt and more in the range of the Bolt and the Tesla 3.

The advantage is?

Just onebother thought: the Volt with the ICE running gives a much more refined ride than the i3 with the sewing machine chattering away in the back. One article I read put it very well: sometimes a big engine running slow is much better than a small engine running faster.

And I say the Volt has the advantage in this area as a person who drives an i3 every day.

Many gas stations in my area have either closed shop, or torn up the gas pumps to focus on selling beer, lottery tickets and snacks.
As electric cars in various forms gain market share, this trend will continue. Perhaps the day will come in a few decades when so many people use electrics, that gasoline becomes only a niche product.

gas has been a “loss leader” for a very long time. Back in the '90s I was a part time pump jockey and occasionally would see the invoices when we received a shipment. even back then (when gas was around $1.00/gal) the mark-up was only a few cents per gallon. IIRC it was 4 cents for regular, and 8 cents for premium.

The only example of a technology happening to be expensive and not great is not proof the technology is bad. You should first look at the details and see if the problem is implementation or the fundamental tech.

For example, you might look at the cost of CNG cars and conclude that CNG is expensive and has no advantages. Except that there’s only a couple models being made, and it’s just the manufacturer slapping a big premium on the price. The cost of CNG bottles and a gas handling fuel injector bank would only add a few hundred bucks to a mass market vehicle, it’s just a chicken-egg problem with CNG stations.

Similarly, based on the fundamentals, a series hybrid is cheaper than a parallel hybrid or pure electric vehicle with the same range, and more fuel efficient than a parallel hybrid under nearly all use cases. The *reason *it’s more efficient to have more battery range (which means less gas needs to be burned), thus it’s better than a parallel hybrid. And you need a smaller battery so it’s better than a pure EV.