I have to admit never having understood this concept.
So, you power your home with your car battery.
You need to go somewhere. Your battery is now 50% depleted.
There's an emergency, you need to evacuate. Your battery is 50% depleted.
There's an emergency. Power is out. You use your car battery to power your home. You have to go out for supplies. Your family is left without power at home while you drive off into the darkness.
Etc.
Assuming a 90% round-trip efficiency (it could be worse), this means you will spend 11% for the energy you will use at home if it has to go in and out of your EV.
Finally, a decade later (or less), you'll have to replace the vehicle's battery at a cost of $25K or more.
Can someone explain how this makes any sense at all?
You have solar. The truck covers night time, bad solar days, and use the truck to power other people’s freezers so they have food or electric chainsaws to remove fallen trees.
To the extent that the following claims are true, V2H makes a lot of sense:
- The battery in your vehicle is way bigger than you actually need for expected and surprise daily uses. You have at least a few hours warning before trips >150mi or are comfortable needing to fast-charge.
- The lifetime of your vehicle's battery is longer than the lifetime of other components. This can be because of the afformentioned way-too-big battery, because intelligent charging avoids the 80-100% range, or due to new chemistries like LiFePO4
- The variation between min and max electricity price is substantially higher than battery inefficiency.
These factors seem mostly false for the first generation of electric vehicles (Leafs, etc.) but much more true for newer EVs with giant batteries. People seem pretty comfortable having a petrol car in their garage with less than 150mi of gas, so it's not surprising they'd be willing to do the same with an EV.
It depends on the expected time of power outages. I live somewhere with a fragile grid, but utility outages aren't necessarily disasters where you'll need to evacuate.
A lot of people have whole house generators, but they're expensive to operate and maintain, if your car can power your house for a few hours, that would be enough for most outages and then when power comes back you can charge the car again. You probably don't want to be driving in the kind of weather where utility power will be out for 48 hours. Doubly so at night. If you must get supplies, you would likely go during the day and the family would just have to deal with lack of power, same as status quo for most.
Reasonably sized whole house generators start around $10k, so rolling similar capability into your car makes some sense. A 30A 240v portable generator is a lot less money, but having it as part of your vehicle is way more portable. Personally, I have a portable generator for my well pump, and I'd love to pay a little extra for my next car to be able to replace that generator. I don't think I'll be able to have a car replace the 35 kW whole house generator anytime soon though; but that generator should have decades of light service in it.
During the end of a dry summer, large swathes of California have the power intentionally shut off for days at a time if moderate to high winds are expected. In those cases there is no emergency at all, so using a car battery works great.
As to your concern about the house losing power when you go on an errand, that is pretty much a non-issue because losing power for an hour or two will not cause food spoilage, unacceptable HVAC conditions, not depleted batteries in flashlights or electronics.
As far as range anxiety, I think it really depends on the location and types of expected disasters. For example where I live the top concern is earthquakes where you may need to flee a fire. In that case even just 10% battery will get you well away from the impacted disaster area to somewhere you could charge back up. In a place with hurricanes that calculus will be very different and this solution may not be a good idea.
As to your concerns about battery wear and replacement costs, I’ve been hearing that line since I got a Prius in 2003. The problem was way overstated then, and is even less of a concern now. With the exception of truly terrible design (Nissan Leaf) battery packs are very well managed now and will last quite long for the average user. In addition, almost no pack actually needs total replacement, there is now a robust and mature industry around refurbishing packs and replacing only the cells that have actually gone bad in a pack for significantly lower cost than total replacement. That industry will only grow and improve as the EV market expands.
The LEAF batteries are air-cooled (not particularly well, especially as compared to liquid cooled batteries that most other pure EVs use). They’re also relatively small, meaning typical use will cycle them deeper than a car with 3x the range.
As a result, they lose capacity far faster than other mainstream EVs.
I’m a 2015 LEAF owner for almost exactly 9 years. In that time and only 25K miles, I’ve lost a little over 15% of the battery capacity. A Tesla would have lost about 2-3% over similar service. (I also feel the loss quite a bit more, starting with a range that was optimistically estimated at 85-90 miles when brand new.) The 2015 packs were supposed to be better than the older gen batteries (and probably are), but it’s still a pretty poor design if longevity and range retention is your priority.
I also had the pack disassembled and a module changed under warranty after it degraded much faster than the sibling modules.
Despite all that, I do enjoy most aspects of the car; we live in a city and have plenty of very short-range trips where the car is quite nicely matched and pleasant to use.
I can't find any news article about that, but I remember that Nissan gives some Leafs to a city taxis. And was a total nightmare for these taxis in a single year. Battery capacity dropped significantly
Indeed! I bought that car because there was $10K in government cheese against a cost of around $30K. It meant I got a decent car, got to experience EV ownership (that I was curious about/interested in), and all for ~$20K.
The alternative for me was never going to be a $50K EV, but rather a $10K used ICE car. I'm happy with the choice overall and while we can technically afford any new car we wanted, spending more than that felt wasteful, so the tradeoffs you mention are entirely real forces on both Nissan and prospective Leaf buyers.
other issues aside, why are people always so obsessed about what happens when "there's an emergency"?
I remember 15 years ago, when unlimited-talk cellphone plans began to be price-competitive with copper-wire home phones, all these people were trying to justify having copper-wire home phone lines because of "emergencies".
"What if the power went out? How would you call 911?"
I view emergency preparedness as part of my responsibility to my family (and, to a lesser extent, to my community). So much so that this seems like a strange question.
People worry about what happens when there’s an emergency because people die in mishandled emergencies and failing to think ahead tends to increase this risk.
> why are people always so obsessed about what happens when "there's an emergency"?
Because that's when what you prepared and did not prepare for matters?
I'll use an unrelated parallel. I've done a lot of work in aerospace, often covering systems that are in a range between critical and life support.
If we design for ideal or normal conditions, bad things happen and people die. We have to design for a range of failure-tolerance levels. For example, a critical life support system might require that it continue to function property with as many as three failures, whereas a flight system might specify two.
We obsess over these things because they matter when things go wrong, not before.
Same with life. You have various kinds of insurance for when things go wrong. Same with vehicles, energy and food.
Back a couple of years ago (I think it was that long) we had severe fires in CA. People with Teslas were told not to charge. They had serious problems.
The difference between a normal F150 and an electric F150 is that you can obtain hundreds of miles of range in five minutes at tens of thousands of locations. In most of the country, this means you have access to fuel every two to five miles. It also means you can safely keep hundreds of miles of range in inexpensive containers at home. It would be easy to decide to keep a thousand miles of fuel that you can easily carry with you. Even easier and safer if it is diesel. This is impossible with electric vehicles.
Under normal conditions electric vehicles --and the charging network that support them-- are great. If you limit assessment of risk to normal conditions you'd be making a big mistake.
Before you say "it can't happen". Well, the pandemic taught us otherwise. I used to live less than a mile from the epicenter of the last powerful earthquake in CA. Lots of people turn into cavemen when that happens. I won't recount the things I say. Let's just say I was both surprised and not surprised. Things like people (my neighbors) taking dozens of cases of water they did not need, making it difficult for those who needed it to have enough of a supply. People can be absolute assholes that way.
I would not want to be in a situation where an electric vehicle becomes the difference between my family being safe and not. And using one to power my house --giving up range-- would be dumb as fuck. Before people get bent out of shape, imagine our electric future, where everything in your home is electric, including heating and cooling. You can easily consume 5 kW per hour for 10 or more hours per day. That means depleting over 50 kWh from your vehicle's battery in just one day. Yeah. In an emergency, you might have to travel 100 miles or more before being able to charge. One reason is likely to be that charging stations become overwhelmed. Yeah. Bad idea.
Another interesting variant on the theme. We have multiple vehicles. All I need is a hose to transfer fuel from one to the next and maximize range. In fact, I can transfer fuel from my vehicles into containers and then use the remaining vehicle to get out.
This isn't about being paranoid. The pandemic taught us a bunch of lessons we should not forget. Living life like black swan events can never happen isn't smart, particularly if your loved ones depend on the decisions you make for their wellbeing.
Here in the SF bay area there have recently been a lot of power outages due to fire danger where it's just for a day or so. Nobody's evacuating, nobody has to go out for supplies, you really just want to turn the lights on, cook dinner, charge your phones, and keep your fridge cold. If you can power your home from your car for a day that seems quite helpful.
Part of this is that your fears about the time the battery lasts and the cost to replace it may be unfounded. Batteries keep getting cheaper, and over those 10 years, you might really only get down to 75-80% capacity (Tesla, for instance, warranties above 70% for ten years or 100k miles, and there are people with batteries at 300k now, they last much longer).
Batteries in cars that are ten years old now may not fare as well. But we’ve just seen this explosion of improvement in technology. Today’s batteries last longer, and tomorrow’s will last longer than that.
For many it would be the other way around. They buy the truck because the want a truck. The integrated home powering is a nice extra option.
I’d like my next vehicle to be an EV. A truck is a little big for my needs (my cars have all been Nissan Sentras, Honda Civics, or Honda CR-Vs) but I’m in a low density area where there is no place something bigger would cause problems, and unlike an ICE truck an EV truck does not have a ridiculous cost per mile so I would be OK with a truck except for the higher upfront cost.
At the initial pricing they said they were aiming for an F-150 Lightning with just the consumer EV rebate plus the add ons for home powering would have been cheaper than getting an EV that doesn’t power the house plus a Tesla Powerwall.
If I had to buy a car right now I’d probably get a Chevy Bolt and deal with house power with a propane powered generator. Propane instead of gasoline because propane doesn’t go bad after long storage. A generator is not as nice as a battery because my loads during a power would be mostly intermittent. I’d either have to start and stop the generator a lot or waste a lot of fuel idling.
Thus I’d prefer a battery system but they are a lot more expensive than a generator, largely because you need enough battery capacity for the whole outage. With a generator you just need enough fuel storage for the outage or a willingness to occasionally go buy more fuel during the outage.
It might be reasonable to do a mixed approach. A battery with enough capacity to handle a few hours plus a generator that could be used to charge the battery. I’ve not yet seriously analyzed this.
> There's an emergency. Power is out. You use your car battery to power your home. You have to go out for supplies. Your family is left without power at home while you drive off into the darkness
As opposed to your family not having power both when you are out for supplies and when you are home?
It turns a power outage from an event where your family is without power for the whole event into an event where your family is without power during the intersection of the time of the power failure and the time you are out getting supplies.
For most of your other scenarios where you need to evacuate and your battery is 50% depleted because you were powering the house before evacuating that will usually not be a problem because most unexpected evacuations don’t require evacuating a great distance.
EVs these days have a lot more battery capacity than many people need.
Like, if my car is 50% depleted I can still use it for 3-4 days for anything I’d need to do.
Main point for me if the power goes out would be to keep the refrigerator and freezer going. Those will be fine if I go on a quick trip. Family will be fine too. We have flash lights. Seriously, I dot understand why you’d think that would be such a bad scenario?
Many people live in areas that aren’t all that car dependent anyway. I can just walk to the grocery or hardware store.
The size of modern EV batteries are so big that many people will likely see their batteries degrade due to age rather than charging cycles. I go through like 1-2 cycles a week, and those are 20-80% cycles of slow charging, so very gentle on the battery.
I would love to get some extra value out of that battery with V2H or V2G. I really don’t think it’ll shorten the life of the car significantly.
It’s possible that many early generation EVs need one battery replacement in their lifetime regardless. Isn’t it then better to have had some of that cost covered by making some money from V2G?
Compared to current costs, yes. Power consumption will be closer to supply production curves instead of demand curves. Peak production is a massively burdensome level of production that requires significant over-engineering. It often requires significantly less efficient and costly technologies to be used. often times resulting it significant maintenance costs.
Yes, since to migitgate the worst of the climate catastrophe we'll have to get off fossils for electricity generation, and then we're dealing with supply peaks and through, instead of demand peaks and throughs.
26 comments
[ 3.0 ms ] story [ 72.9 ms ] threadSo, you power your home with your car battery.
You need to go somewhere. Your battery is now 50% depleted.
There's an emergency, you need to evacuate. Your battery is 50% depleted.
There's an emergency. Power is out. You use your car battery to power your home. You have to go out for supplies. Your family is left without power at home while you drive off into the darkness.
Etc.
Assuming a 90% round-trip efficiency (it could be worse), this means you will spend 11% for the energy you will use at home if it has to go in and out of your EV.
Finally, a decade later (or less), you'll have to replace the vehicle's battery at a cost of $25K or more.
Can someone explain how this makes any sense at all?
- The battery in your vehicle is way bigger than you actually need for expected and surprise daily uses. You have at least a few hours warning before trips >150mi or are comfortable needing to fast-charge. - The lifetime of your vehicle's battery is longer than the lifetime of other components. This can be because of the afformentioned way-too-big battery, because intelligent charging avoids the 80-100% range, or due to new chemistries like LiFePO4 - The variation between min and max electricity price is substantially higher than battery inefficiency.
These factors seem mostly false for the first generation of electric vehicles (Leafs, etc.) but much more true for newer EVs with giant batteries. People seem pretty comfortable having a petrol car in their garage with less than 150mi of gas, so it's not surprising they'd be willing to do the same with an EV.
A lot of people have whole house generators, but they're expensive to operate and maintain, if your car can power your house for a few hours, that would be enough for most outages and then when power comes back you can charge the car again. You probably don't want to be driving in the kind of weather where utility power will be out for 48 hours. Doubly so at night. If you must get supplies, you would likely go during the day and the family would just have to deal with lack of power, same as status quo for most.
Reasonably sized whole house generators start around $10k, so rolling similar capability into your car makes some sense. A 30A 240v portable generator is a lot less money, but having it as part of your vehicle is way more portable. Personally, I have a portable generator for my well pump, and I'd love to pay a little extra for my next car to be able to replace that generator. I don't think I'll be able to have a car replace the 35 kW whole house generator anytime soon though; but that generator should have decades of light service in it.
As to your concern about the house losing power when you go on an errand, that is pretty much a non-issue because losing power for an hour or two will not cause food spoilage, unacceptable HVAC conditions, not depleted batteries in flashlights or electronics.
As far as range anxiety, I think it really depends on the location and types of expected disasters. For example where I live the top concern is earthquakes where you may need to flee a fire. In that case even just 10% battery will get you well away from the impacted disaster area to somewhere you could charge back up. In a place with hurricanes that calculus will be very different and this solution may not be a good idea.
As to your concerns about battery wear and replacement costs, I’ve been hearing that line since I got a Prius in 2003. The problem was way overstated then, and is even less of a concern now. With the exception of truly terrible design (Nissan Leaf) battery packs are very well managed now and will last quite long for the average user. In addition, almost no pack actually needs total replacement, there is now a robust and mature industry around refurbishing packs and replacing only the cells that have actually gone bad in a pack for significantly lower cost than total replacement. That industry will only grow and improve as the EV market expands.
Source please.
As a result, they lose capacity far faster than other mainstream EVs.
I’m a 2015 LEAF owner for almost exactly 9 years. In that time and only 25K miles, I’ve lost a little over 15% of the battery capacity. A Tesla would have lost about 2-3% over similar service. (I also feel the loss quite a bit more, starting with a range that was optimistically estimated at 85-90 miles when brand new.) The 2015 packs were supposed to be better than the older gen batteries (and probably are), but it’s still a pretty poor design if longevity and range retention is your priority.
I also had the pack disassembled and a module changed under warranty after it degraded much faster than the sibling modules.
Despite all that, I do enjoy most aspects of the car; we live in a city and have plenty of very short-range trips where the car is quite nicely matched and pleasant to use.
The alternative for me was never going to be a $50K EV, but rather a $10K used ICE car. I'm happy with the choice overall and while we can technically afford any new car we wanted, spending more than that felt wasteful, so the tradeoffs you mention are entirely real forces on both Nissan and prospective Leaf buyers.
People worry about what happens when there’s an emergency because people die in mishandled emergencies and failing to think ahead tends to increase this risk.
Because that's when what you prepared and did not prepare for matters?
I'll use an unrelated parallel. I've done a lot of work in aerospace, often covering systems that are in a range between critical and life support.
If we design for ideal or normal conditions, bad things happen and people die. We have to design for a range of failure-tolerance levels. For example, a critical life support system might require that it continue to function property with as many as three failures, whereas a flight system might specify two.
We obsess over these things because they matter when things go wrong, not before.
Same with life. You have various kinds of insurance for when things go wrong. Same with vehicles, energy and food.
Back a couple of years ago (I think it was that long) we had severe fires in CA. People with Teslas were told not to charge. They had serious problems.
The difference between a normal F150 and an electric F150 is that you can obtain hundreds of miles of range in five minutes at tens of thousands of locations. In most of the country, this means you have access to fuel every two to five miles. It also means you can safely keep hundreds of miles of range in inexpensive containers at home. It would be easy to decide to keep a thousand miles of fuel that you can easily carry with you. Even easier and safer if it is diesel. This is impossible with electric vehicles.
Under normal conditions electric vehicles --and the charging network that support them-- are great. If you limit assessment of risk to normal conditions you'd be making a big mistake.
Before you say "it can't happen". Well, the pandemic taught us otherwise. I used to live less than a mile from the epicenter of the last powerful earthquake in CA. Lots of people turn into cavemen when that happens. I won't recount the things I say. Let's just say I was both surprised and not surprised. Things like people (my neighbors) taking dozens of cases of water they did not need, making it difficult for those who needed it to have enough of a supply. People can be absolute assholes that way.
I would not want to be in a situation where an electric vehicle becomes the difference between my family being safe and not. And using one to power my house --giving up range-- would be dumb as fuck. Before people get bent out of shape, imagine our electric future, where everything in your home is electric, including heating and cooling. You can easily consume 5 kW per hour for 10 or more hours per day. That means depleting over 50 kWh from your vehicle's battery in just one day. Yeah. In an emergency, you might have to travel 100 miles or more before being able to charge. One reason is likely to be that charging stations become overwhelmed. Yeah. Bad idea.
Another interesting variant on the theme. We have multiple vehicles. All I need is a hose to transfer fuel from one to the next and maximize range. In fact, I can transfer fuel from my vehicles into containers and then use the remaining vehicle to get out.
This isn't about being paranoid. The pandemic taught us a bunch of lessons we should not forget. Living life like black swan events can never happen isn't smart, particularly if your loved ones depend on the decisions you make for their wellbeing.
Batteries in cars that are ten years old now may not fare as well. But we’ve just seen this explosion of improvement in technology. Today’s batteries last longer, and tomorrow’s will last longer than that.
A decade or less? Where are you getting that from?
It's not a great idea when you could just get a home battery without blowing money on the integrated pickup truck.
I’d like my next vehicle to be an EV. A truck is a little big for my needs (my cars have all been Nissan Sentras, Honda Civics, or Honda CR-Vs) but I’m in a low density area where there is no place something bigger would cause problems, and unlike an ICE truck an EV truck does not have a ridiculous cost per mile so I would be OK with a truck except for the higher upfront cost.
At the initial pricing they said they were aiming for an F-150 Lightning with just the consumer EV rebate plus the add ons for home powering would have been cheaper than getting an EV that doesn’t power the house plus a Tesla Powerwall.
If I had to buy a car right now I’d probably get a Chevy Bolt and deal with house power with a propane powered generator. Propane instead of gasoline because propane doesn’t go bad after long storage. A generator is not as nice as a battery because my loads during a power would be mostly intermittent. I’d either have to start and stop the generator a lot or waste a lot of fuel idling.
Thus I’d prefer a battery system but they are a lot more expensive than a generator, largely because you need enough battery capacity for the whole outage. With a generator you just need enough fuel storage for the outage or a willingness to occasionally go buy more fuel during the outage.
It might be reasonable to do a mixed approach. A battery with enough capacity to handle a few hours plus a generator that could be used to charge the battery. I’ve not yet seriously analyzed this.
If you can save your freezer and have a little bit of light that helps a lot.
In worst case you probably have a generator somewhere
As opposed to your family not having power both when you are out for supplies and when you are home?
It turns a power outage from an event where your family is without power for the whole event into an event where your family is without power during the intersection of the time of the power failure and the time you are out getting supplies.
For most of your other scenarios where you need to evacuate and your battery is 50% depleted because you were powering the house before evacuating that will usually not be a problem because most unexpected evacuations don’t require evacuating a great distance.
Like, if my car is 50% depleted I can still use it for 3-4 days for anything I’d need to do.
Main point for me if the power goes out would be to keep the refrigerator and freezer going. Those will be fine if I go on a quick trip. Family will be fine too. We have flash lights. Seriously, I dot understand why you’d think that would be such a bad scenario?
Many people live in areas that aren’t all that car dependent anyway. I can just walk to the grocery or hardware store.
The size of modern EV batteries are so big that many people will likely see their batteries degrade due to age rather than charging cycles. I go through like 1-2 cycles a week, and those are 20-80% cycles of slow charging, so very gentle on the battery.
I would love to get some extra value out of that battery with V2H or V2G. I really don’t think it’ll shorten the life of the car significantly.
It’s possible that many early generation EVs need one battery replacement in their lifetime regardless. Isn’t it then better to have had some of that cost covered by making some money from V2G?
We shouldn’t have to build more capacity than we need and currently we have a lot of idle capacity most of the day because we build for peak.
so yes. it would still be lower.