V2H/ V2G and battery cycles

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rphillip
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V2H/ V2G and battery cycles

Post by rphillip »

Greetings
I am new to the AEVA and this forum. I had a quick search of earlier posts, and didn't find anything directly relevant to this question.

I was talking to a friend last week. She wants to buy an EV in a year or so. I advised her to wait until it was feasible to use an EV for Vehicle to Grid or Vehicle to House. The WA gov't is likely to enable this in the near future. I am looking at the same thing.

Her response was that this is a bad idea, because it would increase the cycles on the battery, and thereby reduce the battery life. In both our cases the vehicle is likely to be at home and connected to solar PV during much of the day.

I would have thought that V2G/H functions would not deeply draw down the battery in this context.

What are people's views about a potential reduction in battery life when extra cycle occur through V2G/H?
Rob
antiscab
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Re: V2H/ V2G and battery cycles

Post by antiscab »

depends upon the car, the chemistry and what cooling the battery has

LFP batteries, and a few of the more "resilient" types don't degrade much with large number of cycles, and would be fine for this application.
cycle life is getting beyond the service life of the car (15+ years)
The battery in my Vectrix is 11 years old, and still going, despite doing a lifetime Ah of 100'000Ah from a 60Ah nominal battery

Cars sold now with DC fast charge capability should be able to support V2G, so waiting doesn't really help
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells
T1 Terry
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Re: V2H/ V2G and battery cycles

Post by T1 Terry »

The cycle life used as an EV can be stressful on the battery because the current draw is high and these days, often the recharge is rapid and sometimes from 100% to 0%, but that is more in the DIY builds than the factory builds.
Used as a house battery, the discharge load is a lot less and the recharge is over a longer period. With LFP/LYP batteries, anything between 20% SOC and 90%SOC limited to a 1CA charge/discharge rate, doesn't actually count as a cycle as such.
We design and install off grid systems for RV's and off grid houses and we have battery system into their 11th yr and still returning 100% capacity using the manufacturers capacity test rate, discharged from 100% SOC to 0% SOC in 2 hrs. They are not showing any sign of deterioration after 4,000 days 24hr use.
The other thing to keep in mind, exhausted EV batteries that are no longer up to doing the job, still make great house batteries, so the house battery use is clearly easier on the battery than the EV use.

T1 Terry
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sleeperpservice
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Re: V2H/ V2G and battery cycles

Post by sleeperpservice »

This does concern me as well as it sounds like a great idea but if it degrades the battery quicker then this will have to be weighed up.

As you said no other cars work with V2G/H and the existing cars will not be able to unless their inbuilt logic is upgraded, highly unlikely I would assume as the vehicle manufacturers would like to sell you new features.

Also the current CCS standard does not allow for bi-directional charging yet @Bryce has written on the topic

https://thedriven.io/2020/07/21/the-roa ... -charging/

I also saw somewhere, cant find the link, that the inverter necessary for the Leaf for V2H was ~$10k. Ridiculously steep given I don't understand how it differs from a hybrid solar inverter very much.

Given I've had our car for 18 months, done 28000kms and filled it with 3.8MWh. During that time Ive imported 5MWh, ~10kWh a day, into the house, not including car charging outside of solar hours. If we had V2H and derived half from the car battery then that would have been like adding ~18000 very gentle kms to the odometer. I'll lookup tonight what the car reports as the number of cycles. When I last looked it seemed lower than I expected and our battery still reports 100% SOH

House loads will be relatively gentle, so i hope it wont be too bad and there would need to be checks to stop it sucking the battery dry but again cars now don't support this and probably wont soon imo.

Wonder how is that going to affect car and battery warranties?
rphillip
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Re: V2H/ V2G and battery cycles

Post by rphillip »

Thanks for the replies so far...
Summary.
1. V2G/H shouldn't affect the battery much.
2. Current EVs and gov't regulations probably don't support this yet (but they should soon...)
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brendon_m
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Re: V2H/ V2G and battery cycles

Post by brendon_m »

3rd point
Dedicated home storage is plummeting in price so you may not want to bother with using your car battery which won't always be connected to the house. V2x is a handy feature to have but personally I think it would be better as a supplement to home storage rather than a replacement for.
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jonescg
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Re: V2H/ V2G and battery cycles

Post by jonescg »

As others have noted, my EV takes more than it gives. So it would require more workplace charging during the day to be remotely viable.
AEVA National President, retiring WA branch chair.
antiscab
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Re: V2H/ V2G and battery cycles

Post by antiscab »

workplace charging and bringing the power home would allow me to take the house offgrid economically. Now to put up a big solar array at work
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells
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Re: V2H/ V2G and battery cycles

Post by T1 Terry »

rphillip wrote: Thu, 25 Nov 2021, 16:37 Thanks for the replies so far...
Summary.
1. V2G/H shouldn't affect the battery much.
2. Current EVs and gov't regulations probably don't support this yet (but they should soon...)
The SA energy network does not deem a V2G to be a household battery that would get the great tariffs or good FiT for use during peak power times. The reasoning is, the battery is not available on the grid permanently so they can't rely of that capacity being available at any time they may need it.

What voltage EV battery are you looking at, that will really change the equipment available to work with it.

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Bryce
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Re: V2H/ V2G and battery cycles

Post by Bryce »

Hi Paul - that article of mine you're referring to is almost 18 months old now. As I note in that article, CCS is evolving to eventually include V2H and V2G. The latest CCS cars have now moved to include bidirectional V2L (vehicle to load) using the car's inbuilt charger. (Much simpler than the old CHAdeMO DC port V2L system. :-) )

Be interesting to see if the V2H and V2G systems when they come work off the AC plug too....

For more info on the first bidirectional CCS sysme now available, see:
https://thedriven.io/2021/11/04/vehicle ... er-source/

Cheers
Bryce
Current EV drive: 2019 Kona electric, 2010 iMiEV
Also in family: 2019 Renault Zoe
Past drives: 2011 Blade Getz, 2011 Leaf, 2001 Citroen Berlingo conversion
Past Conversions: DC Berlingo, AC Berlingo, AC Sprinter
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Re: V2H/ V2G and battery cycles

Post by mikedufty »

Not something I'd wait for. The install cost at the house end (several thousand $ I think), and additional cost of the EV being equipped means it is unlikely to save you money. If you want to power the house in a blackout that would require a bunch of additional costs. Never mind the hassle of having to work out how much of the battery you are prepared to make available to the house at what times and setting up the control.
If you have a need to run 240V equipment from the car at locations remote enough to have no grid power, but close enough to drive home after using up some of your battery, then it could be worthwhile.
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