> Wouldn't the charge / discharge cycles reduce the life of the car battery?

While I'd presume the answer here is "yes", I'd also presume we're talking like a fraction of the vehicle's lifetime charge cycles. Like, (generously/conservatively) 20 to 40 cycles total over the life of the vehicle, no? How often would you estimate your power going out?

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boulos a day ago | parent | next [-]

The point wouldn't be just for backup during outages. It would be growing your kWh of storage and doing daily TOU optimization. That increases the charge / discharge profile by a lot.

Though for an 80 kWh or larger battery, you're only likely to store up and discharge 10-ish per day maybe this way? (Assuming you have actual dedicated BESS, and this is supplementing that). Still that's ~30 cycles per year, which is nothing in the grand scheme of a vehicle battery.

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hedora 18 hours ago | parent | prev | next [-]

Even if you aggressively used the vehicle for this, you're talking about wearing out a ~ $5-10K battery over many years. For reference, a generator that can do this costs $10K, and would be burning way more than that in propane before the car battery wore out.

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frereubu a day ago | parent | prev | next [-]

Duh, yes, slow brain day.

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jauntywundrkind a day ago | parent | prev [-]

I don't think that wear would be worse than driving around. Unless you go out, recharge, and come back, by definition you only have a single charge single cycle to give.

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3eb7988a1663 a day ago | parent [-]

My thinking is that driving has a typical burn rate (eg 1 kWh/mile or whatever), so the battery will be designed around this load pattern. Using it as a battery backup may be pulling a lot faster than optimal and cause additional wear.

It is probably only a minor impact, but I could believe it is outside the design constraints.

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eldaisfish a day ago | parent [-]

driving an obese, modern EV at highway speeds of around 100 km/h uses about 20 kW.

The average house in the US and Canada uses between 2 - 5 kW around 98% of the time.

	▲	jauntywundrkind a day ago \| parent [-]
		Yeah. A big EV, yeah, can pull 20 kW (29HP) continuous at 60mph (close to 100km/h ish). And much much much more accelerating! It's not continuous at all but just to say it, a 500HP engine translates to a 370kW demand! They also have to endure enormously strong charge cycles, and in many ways that is even more difficult time for the battery. Charging at >1C (better than a one hour charge cycle), at 100kW or whatever (and many cars charge far faster)? That strongly implies a very competent discharge. Charge performance almost always trails discharge performance in batteries, signficisntly, and yet we expect huge charge capacity from EVs, thus their discharge should be even more hard to imagine huge. These batteries in EV are all built with chemistries for huge power dense. Not tuned for energy density (storage) but tuned for power density (instantaneous output). The load here, by compare, is tiny. GM Energy PowerShift is one of the biggest inverters you can get factory for a vehicle and will do 20kW. For reference. Perhaps we could put on a 50kW v2h inverter, power the whole mcmansion. Ignore the fact that the battery is going to last 2 hours. I think even that would be perfectly fine, no worse than a day about the town.