Sulu

Agreed. If the next generation of batteries (Toyota's solid-state battery, for example) are as good as we are led to believe, with high capacity and quick charging, in a compact and light package, normal and plug-in hybrids will not be necessary. Hybrids were meant to be interim, stop-gap solutions because we did not have good enough batteries but they took on a life of their own.

chromedome

I've driven the SUV equivalent of that car, the xDrive40e, and it's an absolute dog because of the added weight. 2400 kg is a heck of a lot to haul using a turbo four-cylinder and I've never gotten the electric range to reach the rated 30 km figure. There's plenty of torque but only if the battery is fully charged. The same drivetrain works better in a lighter sedan like your 530e.

Looking at battery weights and energy densities to get 50 mile PHEV range... Napkin scribbles mainly:

* Tesla Model 3 battery pack weighs 500 kg for 80 kWh = 160 wH per kg
* To get 50 miles of range, you need a 13 kWh pack (based on Model 3 80 kWh getting 300 miles range = 266 wH per mile)
* That 13 kWh pack would weigh 83 kg

That's a bit off since the BMW 530e uses a 9.2 kWh pack and gets 19 miles EPA (a whopping 484 wH per mile), so a 50-mile pack for the BMW would be a huge 24 kWh pack weighing 150 kg, assuming it uses a light and sense configuration like the Model 3.

So a 50-mile BMW sedan PHEV would weigh 1900-2000 kg, compared to the 530e's 1800 kg and Model S 75's 2000 kg curb weights. You're better off going full EV because the Model S 75 with a similar weight can go *250* miles on a charge.

Sulu

You just highlighted a major problem / shortcoming of most of the current plug-in hybrid vehicles, which are built by merely increasing the size of the normal hybrid car's battery. The battery weighs a lot but so does that internal combustion engine and transmission. How much electric range could be added if the ICE drivetrain could be replaced by its weight equivalence in battery?

spwolf

I think main problem here is that their actual hybrid system is useless, so you end up getting 22 mpg when it is out of juice (which is soon). On the other hand, Prius Prime gets same mpg as regular Prius when you are out of battery juice.

Something like Prius Prime, but for LS for instance, which would give you extra 100hp when car is juiced up, would be just fine performance wise. And even without extra juice, you would end up with 60-65hp power from batteries since system could recharge them properly, unlike these 1 motor systems that cant do both at the same time.

spwolf

lots of weight is in casing and electronic, not just actual cells. Prime is around 140kg heavier than regular Prius with 8.8 kwh battery.

venom21

Except the Model S 75 is almost $30000 more expensive fully loaded than my 530e.....

chromedome

Responding to three commenters above:

Sulu: Yes, the most efficient configuration in terms of weight and battery capacity would be a full EV or an EV with a tiny range extender. A hybrid uses an engine with battery assist whereas a PHEV uses a battery with engine assist, putting the latter too close towards EVs in terms of weight. That said, lighter sedans like the 530e are more optimal whereas the xDrive40e and this Cayenne aren't efficient at all.

Spwolf: Even the Toyota dual-motor planetary gear hybrid transmission can't fully charge a Prius Prime battery from zero. My ES hybrid takes 5 minutes of idle running to charge 5% of a 1.4 kWh pack. A 14 kWh pack would need hours of idling to charge - it's much more efficient to use engine power to drive the wheels directly.

As for weight, if a Prius Prime is 140 kg heavier than a Prius, a 50-mile Prius Prime could be 300 kg heavier.

Venom21: Yes because batteries are so expensive. At the moment, anyway. Note that a 50-mile 530e with a 24 kWh pack would probably cost just $3000 more than your 530e (assuming $200 per kWh). That car would effectively be an EV most of the time with the engine only used for extra power and for charging. That car would also be like the Volt which uses an 18 kWh pack for 50-mile range. BMW could have a winner if they figure out how to reduce total weight and not have the battery pack take up trunk space.

Sulu

The goal of a small range-extender in a serial hybrid (plug-in hybrid where the ICE never directly drives the vehicle) is to keep the battery charged at or near maximum charge, not to try to charge the battery from empty.

The reason that we think about plug-in hybrids not charging the battery until empty is because single-motor hybrids, like what Porsche offers, cannot charge while the single electric motor is running. So it must run in EV mode until the battery is empty before switching over the drive motor to generator mode.

But if the hybrid has 2 motor-generators, the motor can drive the vehicle and the generator can trickle charge the battery to keep it topped up, in parallel.

chromedome

That means PHEVs are EVs with an engine tacked on, not like our hybrids that have smaller battery packs. Mine never sees a full charge unless I'm going downhill. A PHEV or a range extender EV would have to be fully charged every day before heading out and the engine is used only for extra power or to top up the battery. Full charging should always be done on mains power.

After all those napkin calculations, I'm wondering why Lexus won't make a 50-mile ES PHEV... The added cost and weight are within reason, maybe $5000 and 200 kg more. I'd love to be able to do my commute and drive around town on electric power alone.

spwolf

But it does not have to charge it fully, it only needs to charge it to provide for 60hp-70hp assist when out of battery. 100-130hp assist would be only when on charged battery.
And for purpose of performance hybrid, it does not need 50 miles of range. It needs 10kwh battery for 25-30m range, which would be enough for 130hp battery output and plenty of performance driving.

And again, most of the extra weight is not in just battery cells... it is all the other stuff too, like charger, etc.

Main part here is that the car would get extra 100hp when charged, and still get 40 MPG when out of battery.

bitkahuna

iTrader: (20)

spwolf

I feel like you jumped into conversation without knowing how things work.

Toyota hybrid system is very efficient and is 2 motor system. It means that it can both power the car and charge batteries at the same time. So you have Camry hybrid that gets 10 MPG more than 4cly and plus it is also faster than the same 4cly.

German plugin hybrids are very bad hybrids. They get awful mileage because they have only 1 motor for saving cost. So when you are out of juice, you are literally hauling dead weight because their hybrid system is not good when working on its own - which is going to be often since EV range is very low.

Prius Plugin for instance is as fast and as efficient as regular Prius, while out of plugin power. It does not suddenly get 30 MPG, it is still very efficient vehicle.

Sulu

Toyota/Lexus, Ford, Honda Accord Hybrid, GM Voltec (used in the Volt, Malibu Hybrid and CT6 Hybrid) are 2-motor hybrids. Porsche, MB, BMW are 1-motor hybrids. Dual motor hybrids are more efficient than single motor hybrids.

Yes, if the gasoline engine is running, regardless of what it is driving, is using fuel; but if it is driving a generator, the electricity generated is stored in the battery. If power from the engine that would otherwise be wasted can be used to turn the generator, that is useful; 2-motor hybrids allow this, gathering unneeded, wasted energy into the battery. Even when an engine is driving a vehicle, all of the power available may not be needed and would be wasted. Toyota's 2-motor hybrid system is able to capture that wasted power to turn the generator, storing the "wasted" energy in the battery. That stored electricity can be used later to turn the electric motor to drive the vehicle or provide a boost of additional power to the engine.

This is true, but it is proven that 2-motor, serial-parallel hybrids (Toyota/Lexus, Ford, Honda Accord Hybrid, GM Voltec) are more efficient than simple, 1-motor parallel hybrids. And either type of hybrid -- 2-motor or 1-motor -- is more efficient that a normal, non-hybrid vehicle.


If the hybrid vehicle battery is allowed to discharge to zero, there is no reserve available to provide a boost when extra torque is needed (such as and especially when accelerating from rest), meaning the internal combustion engine must provide all the torque. One way that Toyota hybrids save fuel is because the electric drive motor provides an assist to the engine, so that a smaller, less powerful engine may be used.

In hybrid vehicles that have only one motor-generator (like the European automakers use), the motor can drive the wheels or generate electricity to charge the battery, but not both. So what happens is that the motor drives (or assists) the vehicle until the battery charge is zero, at which time it switches over to work as a generator. When the motor is working as a generator, it cannot work as a motor to drive the vehicle -- the engine has to provide all the power and the vehicle is nothing more than a mild hybrid (only being able to shut off the engine when idling). Mild hybrids are not the most efficient.

The Toyota hybrid system has 2 motor-generators; 1 is constantly turning to drive the vehicle and the other acts as a generator. Additionally, the transmission is designed such that the engine runs at a constant rpm (like a CVT), and is able to provide all of its power to turn the generator (if no extra power from the engine is needed to drive the vehicle), provide all of its power to drive the vehicle (if maximum power is required from the engine) or any proportion in between. The power out of the engine is not wasted. If full power is needed, no power goes to the generator; but if only a little bit (or no power) is needed, the "wasted" power turns the generator to keep the hybrid vehicle battery topped up.

With 1 drive motor and 1 generator, the goal of the Toyota hybrid system is to try to maintain maximum charge in the hybrid vehicle battery; that way the drive motor always runs, to drive the vehicle (when minimum power is necessary to move the vehicle for short distances) or give a boost to the engine. The engine can therefore be smaller (less powerful) than in a normal, non-hybrid vehicle, thus saving fuel.

chromedome

Toyota, Ford and GM hybrids also can run their engines as generators at low speeds, when it's more efficient to use an electric motor's torque than to drive the wheels directly using the engine. Reversing is also done using the drive motor.

Crank rotation turns the motor-generator which both charges the battery and supplies power to the drive motor. It's all in the power control electronics that shuffles current through multiple paths.

Toyota hybrids run engines in the Atkinson cycle for more efficiency, although horsepower and torque numbers are down compared to conventional engines of the same size. The electric motors are supposed to cover those performance gaps.

bitkahuna

iTrader: (20)

i admitted that but thank you, Sulu and chromedome for great explanations.