8 ms·

To Power the Future, Carmakers Flip on 48-Volt Systems

57 points by dwynings 9y ago

maxerickson 9y ago
This article is kind of weird. The push for 48 volt is mostly about secondary systems that need a lot of power and doesn't have much to do with "mild electric" or whatever it is implying. The 21 HP direct boost mentioned in the article is going to be for performance rather than running on electric, the vehicle comes with a 1 Kw-h battery (~5 minutes at full output).
- cameldrv 9y ago
  Whether it's for performance or economy depends on how it's tuned and how the engine is sized relative to the equivalent pure gas car. The attractive things about these mild hybrid systems is that they're cheap, they don't weigh much (so you're not hurting efficiency by hauling around a bunch of batteries and electric motors), and they give you a lot of what a full hybrid (non-plug in) offers. If you're not plugging in, you don't need a big battery, because the hybrid only needs to store the energy from braking, and then deliver it when the car speeds up again. Even though the motor is only 21hp, it provides a lot of low-end torque, which lets you have good acceleration from a stop. This is something modern efficient gas engines are generally bad at, and the immediate acceleration in a lot of modern cars is even worse because of aggressive upshifting to save fuel. The electric motor papers over this deficiency, so you can be more aggressive about using a smaller engine with less low-end torque. The electric motor is also much more powerful than a normal starter motor, so it allows the car to more aggressively shut off the engine at stop lights and even when coasting, and turn it back on very quickly.
  - maxerickson 9y ago
    I buy what you are saying but that particular gas engine is 330 HP.
    - phkahler 9y ago
      At one particular RPM.
- revelation 9y ago
  A basic lack of fundamental understanding has caused the author to quickly fall into an expertly laid trap by marketers that seek to equate 48 volt systems with some sort of "green, hybrid, clean" spirit, leading to such bizarre statements like "The advantages of the new 48-volt systems are considerable. They offer fuel economy improvements of up to 15 percent" Of course it's all about saving a few dollars on copper.
- csours 9y ago
  48 volt is what the industry calls mild hybrid. It allows for much better stop-start systems, which automakers get points for on EPA and European emissions testing. It also allows for 48 volt super-charging and e-assist turbo, as well as a small amount of actual propulsion power (for instance to both start the engine and start the vehicle moving from a complete stop after the stop/start system has been engaged). All of these systems fall under the term "mild hybrid".
- fyfy18 9y ago
  The main advantage of a hybrid system is that the engine can run at a more efficient speed, which is independent of the power being delivered to the wheels. Say you are driving through a town, accelerating from stopped to 30mph then cruising in traffic, the engine will start shortly after you start to move, run at 3000rpm the whole time (or whatever is the most efficient speed), then cut off when you begin the cruise. This is why automatic transmissions now often have 7 or more gears, as it allows the engine to run at a more efficient speed. A hybrid system in comparison is mechanically a lot simpler though: In a Prius the clutches, transmission and alternator have all been replaced by a simple mechanical device with fixed gears and two electric motors. As for the battery the Prius has a 1.3kWh battery, but due to battery longevity (the system tries to keep it charged around 60%) only around 400Wh is actually available for use.
sowbug 9y ago
There is a TLDR for this article, but as far as I can tell it cannot be derived from the article itself. Will someone please explain why 48-volt systems are newly desirable in cars?
- maxerickson 9y ago
  The higher voltage means lower amperage, which means smaller components and so on.
  - dogma1138 9y ago
    You can use thinner cables or have the same cables with less loss. As for actual component size it’s not that simple the higher the voltage the more clearance you need between conductors. So that is bigger airgaps in PCBs and higher rated insulation where gaps aren’t possible.
    - GeorgeTirebiter 9y ago
      True, however, this can also be achieved by different insulating materials. In general, this is not really much of a problem; I agree, it needs to be considered.
- saltcured 9y ago
  You want a higher voltage to allow more power without huge cables due to high current. You want low voltage to avoid high-voltage safety issues which increase engineering, assembly, maintenance, and emergency costs. The 48V system sits right at the boundary where you can deliver enough power for more auxilliary systems and some mild-hybrid techniques including frequent start/stop systems, brief acceleration boost, and regenerative braking. Yet, it's not high enough to require switching to a different electrical wiring safety paradigm. This is similar to the reason power-over-ethernet runs at the voltage it does, or "low voltage" lighting exists for home applications where consumers are moving fixtures around and interacting with the wiring.
  - 9y ago
neonate 9y ago
http://archive.is/PYZ6G http://archive.is/PYZ6G
ju-st 9y ago
> It is diesel's decline, executives and analysts say, that has finally set the stage for mass electrification. While diesel pollution problems became notorious with the Volkswagen test-cheating scandal, the subsequent shift to gasoline is bloating carbon dioxide (CO2) emissions, making the next round of European Union goals harder to meet. > PSA Group, which had previously seen no need for 48V hybrids, now plans to introduce them "across the board" in response to diesel's faster-than-expected decline, the Peugeot maker's programs chief Patrice Lucas told Reuters. > "What automakers are finding is they need more than just advanced combustion engines to reach the fleet average reductions," said Mary Gustanski, Delphi's engineering boss. quoted from http://europe.autonews.com/article/20170923/ANE/170929892/vw-psa-volvo-others-adopt-48-volt-mild-hybrids-in-response-to-diesel http://europe.autonews.com/article/20170923/ANE/170929892/vw...
chiph 9y ago
Some RV makers (both commercial [0] and DIY [1]) are already on 48V systems for their house batteries. Advantages: lighter wiring, can use a higher-voltage alternator that needs less heat dissipation. Note that the system in the Sprinter van is able to run the air conditioner at 100% duty for 8 hours, then allow the alternator to recharge the battery while continuing to run the A/C unit. Which is really impressive (and should be, for the $200k their RVs cost) [0] https://www.youtube.com/watch?v=ofCcnxJxzeE https://www.youtube.com/watch?v=ofCcnxJxzeE [1] https://www.youtube.com/watch?v=LV8fyzOTjsk https://www.youtube.com/watch?v=LV8fyzOTjsk
PhantomGremlin 9y ago
It's too bad that automakers didn't make this change a long time ago. One thing the article didn't mention is that power losses in a wire are a function of the square of the current. So, let's say one needs to deliver 48 watts to a load. In a 48 V system, that's 1 A of current. Using 12 V, that's 4 A of current. Power loss is 16x greater at 12 V for same diameter of wire, loss = (4 A * 4 A) * resistance of wire.[1] Therefore, wires are made thicker in 12 V systems to avoid this. That's a lot of extra weight in a car. Before the nitpickers chime in, I know the above is simplified. But it also clearly explains why long distance power transmission lines run at such high voltages, 230 KV or higher. [1] https://en.wikipedia.org/wiki/Copper_loss https://en.wikipedia.org/wiki/Copper_loss
- bsder 9y ago
  You're not wrong, but you should probably tell the whole story if you're going to post on HN. Primary Objection: Um, Ohms law gives V=IR. And P=IV. So, P=I^2R. Except that P ALSO can be calculated as P=V^2/R. So, we got squared losses anyway and R should go the other direction. WTF? The answer is that a copper wire is a distributed system, not a lumped system. So, you derive the power loss from the generated heat across a differential slice of the line and then integrate over the whole length of the line--which gives you Power=RI^2 in the limit (and V->0 for any individual slice as the differential ->0). It is one of those (un?)fortunate happenstances (like the Bohr hydrogen atom model) where the system in the limit sums to something we already know and leads to a bit of misunderstanding when you confuse two things which appear to be related but really aren't...
  - mindslight 9y ago
    The V in V^2/R would be the voltage drop along the wire, not the total system voltage.
mcguire 9y ago
About a decade ago, wasn't there some interest in moving to 24 volt systems; nothing came of it due to switch failures, IIRC?
- phkahler 9y ago
  It's always been 48V. The problem has been a chicken and egg sort of thing. Its expensive to have both 12 and 48, but you can't go full 48 unless you can source all components for that voltage. Suppliers didn't really commit because there were no real customers.
  - solarkraft 9y ago
    How hard is it to put a DC-DC converter between the systems?
    - phkahler 9y ago
      That's technically and conceptually easy but it costs a lot of money. One approach would be to put a large DC-DC converter on the car and run a 48V bus next to the 12V one. That's a very expensive device, needing to be perhaps a few kilowatts depending which devices are on 48V. It's also a lot of extra wiring, and the need to manage the extra variations in vehicle systems. A second approach would be to put a DC-DC converter only in the devices that need 12V. But that's asking every supplier to change their design to accommodate 48V and the vehicle manufacturers will bitch about the cost increases. It'll be a moderate increase across a LOT of devices. I'm working on a product that uses a highly integrated SoC that has all the regulators needed to connect it directly to the 12V line (it'll run on 6-20V or so). It even has an on-board 5V regulator for additional off-chip devices. The best thing for us would be if the same chip existed but could be connected directly to 48V (not sure what the range is on that) but from a silicon standpoint there is a big difference as well. Adding an external regulator would add cost, and invalidate some of the wake-up features and low current standby capabilities of the chip. There are always "reasons". The only way to make the transition is for someone to make it happen, but again the suppliers who participate may be seeking premium pricing in the beginning because there aren't options.
madengr 9y ago
48 VDC will be good for amateur radio and car audio. Specifically the power amplifiers for both.
- uncle_bob 9y ago
  Noise from high power motors will be the bane of all operators, even when the car just drives by. However the junk yard will soon be a good place to source 48v generators.
  - madengr 9y ago
    I have a Nissan Leaf, but don’t operate mobile with it. The AM reception on its radio is fine, which I’ve heard is a problem in other EVs. Proper EMI mitigation can be done, but these companies may not spend the expense to do it.
ggm 9y ago
This article conflates two things. One: adoption of a 48v standard for powered systems because it's a sweet-spot for efficiency, current draw, systems design. Two: PHEV and the adoption of electric transmission and drive train, which permits a non throttled engine of any form to run at constant high efficiency or not at all and use batteries. Two things. One story. Cars are becoming like common rail deisel with a unified power model for systems integration and cars are becoming like locomotives which use electric traction for systems efficiency.
- klodolph 9y ago
  The 48 V DC "sweet spot" is mostly safety / regulatory. As soon as you get to 50 V, the safety requirements (NEC) change. You can hold on to bare conductors with a 48 V potential across them just fine, even though 120 V AC will kill you and make it hurt the entire time you are dying. 48 V devices can require connections that are inconvenient and large, depending on what you want to power with them. Try running an air conditioner off 48 V and measuring the peak current draw. https://electronics.stackexchange.com/questions/267789/how-safe-is-48v-dc https://electronics.stackexchange.com/questions/267789/how-s...
  - MrBuddyCasino 9y ago
    > You can hold on to bare conductors with a 48 V potential across them just fine Even with wet hands? I was under the assumption the unconditionally safe upper limit was around 24V.
csours 9y ago
> "But skeptics may wonder why engineers are devoting so much effort to developing the mild hybrid systems that could be seen as stopgap measures on the path to a fully electric vehicle fleet." Let's do some napkin math. Assumptions: 1. Gasoline will never exceed $10/gallon. (assumes eventual plant/algae sourcing/some kind of magic). 1a. Vehicles achieve 50 mpg (2 gallons/ 100 miles) via tricks like 48-volt. Thus future gasoline MHEV vehicles cost 20 cents/mile to power, so $20 per 100 miles 2. Batteries get stuck at about $100/kWh. (maybe lithium etc never scales) 2a. Consumers are satisfied with 60 kWh batteries. Thus BEVs cost $6000 more than comparable MHEVs (napkin math) 4. Electricity costs $0.20/kWh (assume some surcharge for the charging station). 4a. Your BEV gets 34 kWh / 100 miles (99 MPGe) Thus to power your BEV costs $6.8 / 100 miles. 5. The difference between 20 and 6.8 is 13.2 - so you are paying off your battery at $13.2 / 100 miles. 6000/13.2 is about 450 --- Conclusion: It will take 45,000 miles to pay off your battery, assuming the competition is a 50 mpg vehicle and gasoline is $10/gallon. Additionally, the initial cost for a BEV is $6000 higher, which is quite significant for entry-level buyers. --- With 33 mpg and $5/g you have $15/100 mile, thus a 80-90,000 mile payoff. With 33 mpg and $3/g you have $9/100 mile, thus 270,000 mile payoff With 33 mpg and $2/g you have $6/100 mile, and you will never pay off the battery investment. With 20 mpg and $3/g you also have $15/100 mile = 90,000 --- Home Solar: add $10,000 to your battery = $16,000 50 mpg and $10/g you have $20/100 mile = 80,000 mile payoff 33 mpg and $ 5/g you have $15/100 mile = 107,000 mile payoff 33 mpg and $ 3/g you have $ 9/100 mile = 179,000 mile payoff 33 mpg and $ 2/g you have $ 6/100 mile = 267,000 mile payoff 20 mpg and $ 3/g you have $15/100 mile = 80,000 mile payoff again
- csours 9y ago
  Replying to myself: One thing the above does not take into account is the feeling of a BEV, which internal combustion and weak hybrids simply cannot match. I deeply feel that luxury customers will demand strong electrified powertrains after experiencing them. Strong hybrids could match the feeling of a BEV, at a similar per-unit cost. One issue is engineering and certification costs - manufacturers can only do so much at once or else shareholders get anxious. Also not included are warranty reserves (how much to set aside per vehicle for warranty costs). More complicated vehicles call for more reserves.
_ph_ 9y ago
Certainly a nice technology, but I think it is 10 years late. This kind of modernized eletrical design of combustion engined cars which enables mild-hybrids should have been standard 5 years ago. Going forward I cannot see a large future for combustion-engined cars at all - for a few few years, plugin hybrids migth be popular for those, who need a lot of range. But pure electric cars are now coming to the market in numbers. I don't think as stated in the article, that in 2025 only 5% of the vehicles sold will be electric, I would assume that number rather for 2020.
- paganel 9y ago
  2020 is only 2 years from now, we’re nowhere close to that 5% number.
  - _ph_ 9y ago
    We are already at over 1% EVs in several important markets in 2017, and the EV sales numbers almost double every year, so 2020 probably won't see 5%, but should be pretty close to that - at least closer than 2025.

57 points by dwynings 9y ago

This article is kind of weird. The push for 48 volt is mostly about secondary systems that need a lot of power and doesn't have much to do with "mild electric" or whatever it is implying. The 21 HP direct boost mentioned in the article is going to be for performance rather than running on electric, the vehicle comes with a 1 Kw-h battery (~5 minutes at full output).

cameldrv 9y ago
Whether it's for performance or economy depends on how it's tuned and how the engine is sized relative to the equivalent pure gas car. The attractive things about these mild hybrid systems is that they're cheap, they don't weigh much (so you're not hurting efficiency by hauling around a bunch of batteries and electric motors), and they give you a lot of what a full hybrid (non-plug in) offers. If you're not plugging in, you don't need a big battery, because the hybrid only needs to store the energy from braking, and then deliver it when the car speeds up again. Even though the motor is only 21hp, it provides a lot of low-end torque, which lets you have good acceleration from a stop. This is something modern efficient gas engines are generally bad at, and the immediate acceleration in a lot of modern cars is even worse because of aggressive upshifting to save fuel. The electric motor papers over this deficiency, so you can be more aggressive about using a smaller engine with less low-end torque. The electric motor is also much more powerful than a normal starter motor, so it allows the car to more aggressively shut off the engine at stop lights and even when coasting, and turn it back on very quickly.
- maxerickson 9y ago
  I buy what you are saying but that particular gas engine is 330 HP.
  - phkahler 9y ago
    At one particular RPM.
revelation 9y ago
A basic lack of fundamental understanding has caused the author to quickly fall into an expertly laid trap by marketers that seek to equate 48 volt systems with some sort of "green, hybrid, clean" spirit, leading to such bizarre statements like "The advantages of the new 48-volt systems are considerable. They offer fuel economy improvements of up to 15 percent" Of course it's all about saving a few dollars on copper.
csours 9y ago
48 volt is what the industry calls mild hybrid. It allows for much better stop-start systems, which automakers get points for on EPA and European emissions testing. It also allows for 48 volt super-charging and e-assist turbo, as well as a small amount of actual propulsion power (for instance to both start the engine and start the vehicle moving from a complete stop after the stop/start system has been engaged). All of these systems fall under the term "mild hybrid".
fyfy18 9y ago
The main advantage of a hybrid system is that the engine can run at a more efficient speed, which is independent of the power being delivered to the wheels. Say you are driving through a town, accelerating from stopped to 30mph then cruising in traffic, the engine will start shortly after you start to move, run at 3000rpm the whole time (or whatever is the most efficient speed), then cut off when you begin the cruise. This is why automatic transmissions now often have 7 or more gears, as it allows the engine to run at a more efficient speed. A hybrid system in comparison is mechanically a lot simpler though: In a Prius the clutches, transmission and alternator have all been replaced by a simple mechanical device with fixed gears and two electric motors. As for the battery the Prius has a 1.3kWh battery, but due to battery longevity (the system tries to keep it charged around 60%) only around 400Wh is actually available for use.

sowbug 9y ago

There is a TLDR for this article, but as far as I can tell it cannot be derived from the article itself. Will someone please explain why 48-volt systems are newly desirable in cars?

maxerickson 9y ago
The higher voltage means lower amperage, which means smaller components and so on.
- dogma1138 9y ago
  You can use thinner cables or have the same cables with less loss. As for actual component size it’s not that simple the higher the voltage the more clearance you need between conductors. So that is bigger airgaps in PCBs and higher rated insulation where gaps aren’t possible.
  - GeorgeTirebiter 9y ago
    True, however, this can also be achieved by different insulating materials. In general, this is not really much of a problem; I agree, it needs to be considered.
saltcured 9y ago
You want a higher voltage to allow more power without huge cables due to high current. You want low voltage to avoid high-voltage safety issues which increase engineering, assembly, maintenance, and emergency costs. The 48V system sits right at the boundary where you can deliver enough power for more auxilliary systems and some mild-hybrid techniques including frequent start/stop systems, brief acceleration boost, and regenerative braking. Yet, it's not high enough to require switching to a different electrical wiring safety paradigm. This is similar to the reason power-over-ethernet runs at the voltage it does, or "low voltage" lighting exists for home applications where consumers are moving fixtures around and interacting with the wiring.
- 9y ago

neonate 9y ago

http://archive.is/PYZ6G http://archive.is/PYZ6G

ju-st 9y ago

> It is diesel's decline, executives and analysts say, that has finally set the stage for mass electrification. While diesel pollution problems became notorious with the Volkswagen test-cheating scandal, the subsequent shift to gasoline is bloating carbon dioxide (CO2) emissions, making the next round of European Union goals harder to meet. > PSA Group, which had previously seen no need for 48V hybrids, now plans to introduce them "across the board" in response to diesel's faster-than-expected decline, the Peugeot maker's programs chief Patrice Lucas told Reuters. > "What automakers are finding is they need more than just advanced combustion engines to reach the fleet average reductions," said Mary Gustanski, Delphi's engineering boss. quoted from http://europe.autonews.com/article/20170923/ANE/170929892/vw-psa-volvo-others-adopt-48-volt-mild-hybrids-in-response-to-diesel http://europe.autonews.com/article/20170923/ANE/170929892/vw...

chiph 9y ago

Some RV makers (both commercial [0] and DIY [1]) are already on 48V systems for their house batteries. Advantages: lighter wiring, can use a higher-voltage alternator that needs less heat dissipation. Note that the system in the Sprinter van is able to run the air conditioner at 100% duty for 8 hours, then allow the alternator to recharge the battery while continuing to run the A/C unit. Which is really impressive (and should be, for the $200k their RVs cost) [0] https://www.youtube.com/watch?v=ofCcnxJxzeE https://www.youtube.com/watch?v=ofCcnxJxzeE [1] https://www.youtube.com/watch?v=LV8fyzOTjsk https://www.youtube.com/watch?v=LV8fyzOTjsk

PhantomGremlin 9y ago

It's too bad that automakers didn't make this change a long time ago. One thing the article didn't mention is that power losses in a wire are a function of the square of the current. So, let's say one needs to deliver 48 watts to a load. In a 48 V system, that's 1 A of current. Using 12 V, that's 4 A of current. Power loss is 16x greater at 12 V for same diameter of wire, loss = (4 A * 4 A) * resistance of wire.[1] Therefore, wires are made thicker in 12 V systems to avoid this. That's a lot of extra weight in a car. Before the nitpickers chime in, I know the above is simplified. But it also clearly explains why long distance power transmission lines run at such high voltages, 230 KV or higher. [1] https://en.wikipedia.org/wiki/Copper_loss https://en.wikipedia.org/wiki/Copper_loss

bsder 9y ago
You're not wrong, but you should probably tell the whole story if you're going to post on HN. Primary Objection: Um, Ohms law gives V=IR. And P=IV. So, P=I^2R. Except that P ALSO can be calculated as P=V^2/R. So, we got squared losses anyway and R should go the other direction. WTF? The answer is that a copper wire is a distributed system, not a lumped system. So, you derive the power loss from the generated heat across a differential slice of the line and then integrate over the whole length of the line--which gives you Power=RI^2 in the limit (and V->0 for any individual slice as the differential ->0). It is one of those (un?)fortunate happenstances (like the Bohr hydrogen atom model) where the system in the limit sums to something we already know and leads to a bit of misunderstanding when you confuse two things which appear to be related but really aren't...
- mindslight 9y ago
  The V in V^2/R would be the voltage drop along the wire, not the total system voltage.

mcguire 9y ago

About a decade ago, wasn't there some interest in moving to 24 volt systems; nothing came of it due to switch failures, IIRC?

phkahler 9y ago
It's always been 48V. The problem has been a chicken and egg sort of thing. Its expensive to have both 12 and 48, but you can't go full 48 unless you can source all components for that voltage. Suppliers didn't really commit because there were no real customers.
- solarkraft 9y ago
  How hard is it to put a DC-DC converter between the systems?
  - phkahler 9y ago
    That's technically and conceptually easy but it costs a lot of money. One approach would be to put a large DC-DC converter on the car and run a 48V bus next to the 12V one. That's a very expensive device, needing to be perhaps a few kilowatts depending which devices are on 48V. It's also a lot of extra wiring, and the need to manage the extra variations in vehicle systems. A second approach would be to put a DC-DC converter only in the devices that need 12V. But that's asking every supplier to change their design to accommodate 48V and the vehicle manufacturers will bitch about the cost increases. It'll be a moderate increase across a LOT of devices. I'm working on a product that uses a highly integrated SoC that has all the regulators needed to connect it directly to the 12V line (it'll run on 6-20V or so). It even has an on-board 5V regulator for additional off-chip devices. The best thing for us would be if the same chip existed but could be connected directly to 48V (not sure what the range is on that) but from a silicon standpoint there is a big difference as well. Adding an external regulator would add cost, and invalidate some of the wake-up features and low current standby capabilities of the chip. There are always "reasons". The only way to make the transition is for someone to make it happen, but again the suppliers who participate may be seeking premium pricing in the beginning because there aren't options.

madengr 9y ago

48 VDC will be good for amateur radio and car audio. Specifically the power amplifiers for both.

uncle_bob 9y ago
Noise from high power motors will be the bane of all operators, even when the car just drives by. However the junk yard will soon be a good place to source 48v generators.
- madengr 9y ago
  I have a Nissan Leaf, but don’t operate mobile with it. The AM reception on its radio is fine, which I’ve heard is a problem in other EVs. Proper EMI mitigation can be done, but these companies may not spend the expense to do it.

ggm 9y ago

This article conflates two things. One: adoption of a 48v standard for powered systems because it's a sweet-spot for efficiency, current draw, systems design. Two: PHEV and the adoption of electric transmission and drive train, which permits a non throttled engine of any form to run at constant high efficiency or not at all and use batteries. Two things. One story. Cars are becoming like common rail deisel with a unified power model for systems integration and cars are becoming like locomotives which use electric traction for systems efficiency.

klodolph 9y ago
The 48 V DC "sweet spot" is mostly safety / regulatory. As soon as you get to 50 V, the safety requirements (NEC) change. You can hold on to bare conductors with a 48 V potential across them just fine, even though 120 V AC will kill you and make it hurt the entire time you are dying. 48 V devices can require connections that are inconvenient and large, depending on what you want to power with them. Try running an air conditioner off 48 V and measuring the peak current draw. https://electronics.stackexchange.com/questions/267789/how-safe-is-48v-dc https://electronics.stackexchange.com/questions/267789/how-s...
- MrBuddyCasino 9y ago
  > You can hold on to bare conductors with a 48 V potential across them just fine Even with wet hands? I was under the assumption the unconditionally safe upper limit was around 24V.

csours 9y ago

> "But skeptics may wonder why engineers are devoting so much effort to developing the mild hybrid systems that could be seen as stopgap measures on the path to a fully electric vehicle fleet." Let's do some napkin math. Assumptions: 1. Gasoline will never exceed $10/gallon. (assumes eventual plant/algae sourcing/some kind of magic). 1a. Vehicles achieve 50 mpg (2 gallons/ 100 miles) via tricks like 48-volt. Thus future gasoline MHEV vehicles cost 20 cents/mile to power, so $20 per 100 miles 2. Batteries get stuck at about $100/kWh. (maybe lithium etc never scales) 2a. Consumers are satisfied with 60 kWh batteries. Thus BEVs cost $6000 more than comparable MHEVs (napkin math) 4. Electricity costs $0.20/kWh (assume some surcharge for the charging station). 4a. Your BEV gets 34 kWh / 100 miles (99 MPGe) Thus to power your BEV costs $6.8 / 100 miles. 5. The difference between 20 and 6.8 is 13.2 - so you are paying off your battery at $13.2 / 100 miles. 6000/13.2 is about 450 --- Conclusion: It will take 45,000 miles to pay off your battery, assuming the competition is a 50 mpg vehicle and gasoline is $10/gallon. Additionally, the initial cost for a BEV is $6000 higher, which is quite significant for entry-level buyers. --- With 33 mpg and $5/g you have $15/100 mile, thus a 80-90,000 mile payoff. With 33 mpg and $3/g you have $9/100 mile, thus 270,000 mile payoff With 33 mpg and $2/g you have $6/100 mile, and you will never pay off the battery investment. With 20 mpg and $3/g you also have $15/100 mile = 90,000 --- Home Solar: add $10,000 to your battery = $16,000 50 mpg and $10/g you have $20/100 mile = 80,000 mile payoff 33 mpg and $ 5/g you have $15/100 mile = 107,000 mile payoff 33 mpg and $ 3/g you have $ 9/100 mile = 179,000 mile payoff 33 mpg and $ 2/g you have $ 6/100 mile = 267,000 mile payoff 20 mpg and $ 3/g you have $15/100 mile = 80,000 mile payoff again

csours 9y ago
Replying to myself: One thing the above does not take into account is the feeling of a BEV, which internal combustion and weak hybrids simply cannot match. I deeply feel that luxury customers will demand strong electrified powertrains after experiencing them. Strong hybrids could match the feeling of a BEV, at a similar per-unit cost. One issue is engineering and certification costs - manufacturers can only do so much at once or else shareholders get anxious. Also not included are warranty reserves (how much to set aside per vehicle for warranty costs). More complicated vehicles call for more reserves.

_ph_ 9y ago

Certainly a nice technology, but I think it is 10 years late. This kind of modernized eletrical design of combustion engined cars which enables mild-hybrids should have been standard 5 years ago. Going forward I cannot see a large future for combustion-engined cars at all - for a few few years, plugin hybrids migth be popular for those, who need a lot of range. But pure electric cars are now coming to the market in numbers. I don't think as stated in the article, that in 2025 only 5% of the vehicles sold will be electric, I would assume that number rather for 2020.

paganel 9y ago
2020 is only 2 years from now, we’re nowhere close to that 5% number.
- _ph_ 9y ago
  We are already at over 1% EVs in several important markets in 2017, and the EV sales numbers almost double every year, so 2020 probably won't see 5%, but should be pretty close to that - at least closer than 2025.