Don't batter packs have a shorter useful life than most of the rest of an EV?
Say you have a 300-mile EV which averages 3 miles/kWh for a full useful capacity of 100 kWh. If the battery degrades to half that capacity the car would only go 150 miles which I think most people would consider well past EoL (manufacturer warranties will replace a vehicle battery once it degrades to 75-80% of original capacity).
However that battery can still hold 50 kWh which would be enough to cover my home energy use for a week (I live in a small apartment and don't run my AC much). For stationary applications the "useful life" of a battery can be much longer than for mobile applications.
I would hazard a guess that the battery becomes effectively useless before “capacity” actually reaches 50%.
I do wonder if this is a matter of going from 500 to 1000 cycles, or if it’s more exponential decay so we’re talking just 100 cycles between “no longer good enough for the EV” to “no longer good enough for the house/grid”.
Vehicle-to-grid would have to pay me a lot if it means I have to scrap my EV after 5 years instead of 10.
And if the power network is going to use half of my EV's battery's cycle-life and pay half my battery's cost, why wouldn't they just buy their own battery?
And if they're only going to activate V2G for a few hours a year, it'll have to pay high hourly rate to cover the cost of the extra car components.
On the other hand, just limiting charge rates in times of high demand doesn't degrade cars' batteries at all. Makes much more sense IMHO.
†Yes, it depends on the battery model, the temperature, the current - but we all know from phones that battery degradation is a real thing.
Same reason why they wouldn't just buy their own solar panels.
At $9/kWh (which is a truly absurd rate) the battery pays for itself in roughly 12 cycles.
At a less insane but still hefty $1/kWh margin, it would pay for itself in roughly 100 cycles.
Of course you wouldn’t scrap your whole EV, you would buy a new battery for your EV with the profits, and ideally end up with both excess income, and a longer overall vehicle lifespan, with longer effective ranges over time.
I’m sure someone has done all the math on this and knows exactly how good and cheap the EV battery has to be in order for this to be worth doing, and it seems like we’re nearly there.
Plus, with the same hardware plus a safety switch in the house, the EV becomes your house battery backup as well.
Discharging and charging your cars battery will cause wear, but I don't think It would be so fair to compare it to the degradation you see in other devices. Tesla has seen some success in getting more from its batteries by managing thermals [2] as well as limiting max and minimum charges to more healthy levels [3, we saw tesla give more capacity to units implying there is a reserve] [4, we know these cars will still drive even after there range is 'exhausted' for some time]
Considering the expense of batteries for cars maybe I wouldn't do it, but It is likely not so bad if you have a car with good power and thermal management
-0, https://batteryuniversity.com/learn/article/capacity_loss -1,https://cleantechnica.com/2018/12/05/60-kwh-nissan-leaf-stil... -2,https://www.teslarati.com/watch-tesla-battery-thermal-manage... -3,https://cleantechnica.com/2017/09/09/tesla-unlocks-extra-bat... -4, https://forums.tesla.com/forum/forums/reserve-power-when-sta...
They just have to have enough capacity to be cost positive after overhead.