[rainbow]

I'd like to learn more about the remuneration to electric car owners as a consequence of battery degradation (due to charging/discharging cycles) in a V2G/V2B (in general, V2X) context.

How is it estimated this economic compense?

Which is the state-of-the-art in compensation models for EV owners?

PS: Scientific articles and academic papers are welcomed.

 

[Mike Schooling]

You should check the WMG paper on v2g and battery degradation.

Our findings from the worlds largest trial (400+ units) aligns with it well.

Clean energy stored in electric vehicles to power buildings

warwick.ac.uk

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[Petriix]

The crucial part of that report is

Given that battery degradation is dependent on calendar age, capacity throughput, temperature, state of charge, current and depth of discharge, V2G is an effective tool that can be used to optimise a battery’s conditions such that degradation is minimised. Hence, taking excess energy from an idle EV to power the grid actually keeps the battery healthier for longer.

 

[cdlb]

Shhh, don't tell anybody, otherwise they'll start charging EV owners for a "battery health improvement" service...

 

[Mike Schooling]

just a thought. if you are looking for real owner experience, there is the "ovo v2g" facebook group.

A few have been recording their SOH over the trial. we have a couple of years of degradation now for the trial which makes for interesting reading.

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[WithEthyl]

The other interesting point V2G raises, is how does a buyer (or the car leasing or finance company) of a car know whether the vehicle has been previously used for V2G and what wear and tear it has done to the battery?

Most car valuations are driven off mileage as an indicator of vehicle wear and tear, but V2G breaks that linkage, potentially you could have low mileage vehicles with significant battery degradation.

 

[Mike Schooling]

The other interesting point V2G raises, is how does a buyer (or the car leasing or finance company) of a car know whether the vehicle has been previously used for V2G and what wear and tear it has done to the battery?

Most car valuations are driven off mileage as an indicator of vehicle wear and tear, but V2G breaks that linkage, potentially you could have low mileage vehicles with significant battery degradation.

For Nissan, there is a bms parameter for total throughput measured in Ah

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[SpaceInvader]

The crucial part of that report is

Given that battery degradation is dependent on calendar age, capacity throughput, temperature, state of charge, current and depth of discharge, V2G is an effective tool that can be used to optimise a battery’s conditions such that degradation is minimised. Hence, taking excess energy from an idle EV to power the grid actually keeps the battery healthier for longer.

<confused face>

So, on the one hand there is the widely held expectation (referenced in EV warranties) that cycling the battery causes degradation over time.

On the other hand we have this report that cycling the batteries does the opposite.

Or is it claiming that if you implement v2g but don't really make much use of the battery it doesn't hurt? In which case how will v2g make much difference to the grid?

 

[Mike Schooling]

So, on the one hand there is the widely held expectation (referenced in EV warranties) that cycling the battery causes degradation over time.

On the other hand we have this report that cycling the batteries does the opposite.

Or is it claiming that if you implement v2g but don't really make much use of the battery it doesn't hurt? In which case how will v2g make much difference to the grid?

No. The basic premise is that by using v2g, you spend less time at high states of charge but with higher throughput which for the chemistries tested appears to be better for them them than less throughput but greater time at higher SOC as you have with unmanaged charging.

This broadly aligns with our initial findings on the 400+ unit trial.

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[Kingpleb1]

Its because the V2g is much gentler in input and output from the pack and over a longer period.
it also doesnt often go below say 25% or above 85% by default.

The other way youd notice if V2G had been used on a vehicle like the leaf is possibly checking the amount of QC/L1/2 and such charges being very high

 

[Mike Schooling]

Its because the V2g is much gentler in input and output from the pack and over a longer period.
it also doesnt often go below say 25% or above 85% by default.

The other way youd notice if V2G had been used on a vehicle like the leaf is possibly checking the amount of QC/L1/2 and such charges being very high

Correct over than QC count.

We have a fair number of trial participants who are happily leaving the car plugged in for days/weeks at a time.

Even those commuting its typically only once per day which is the same as charging on route at a rapid.

The throughput figure in the BMS is the only real way to know.

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[Kingpleb1]

Correct over than QC count.

We have a fair number of trial participants who are happily leaving the car plugged in for days/weeks at a time.

Even those commuting its typically only once per day which is the same as charging on route at a rapid.

The throughput figure in the BMS is the only real way to know.

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I wonder if thats something leafspy could be updated to show maybe...

 

[barneyd]

I looked at joining the Electric Nation V2G trial but the terms were atrocious.

You had to be plugged in from 6pm so no getting home late from work or using the car in the evening. They paid 60p incentive payment which wouldn’t be in cash. There was no mention of an export rate so it wasn’t clear if they could take energy you had paid for and export it without buying it and if you didn’t plug in for 10 days a month, they would kick you off the trial and charge you £2,000 to remove the kit.

Even if you completed the trial, they wanted £500 for the kit so basically giving back all of the (non cash) incentive payments and finding the same again from your own pocket.

Sounds like the kind of deal that would be dreamed up by a couple of loan sharks. Trouble with finance people is they are too busy looking after their own interests to think about the product and too stupid to realise that.

 

[Petriix]

I think I'd pay £500 for a programmable unit that could do vehicle to home. I'm at home most of the time I'm using electricity and could happily store and use much of the solar generation I currently export. It would pay for its self in around 3 years; maybe less if I used something like Go or Agile to charge overnight in the winter.

Shame they haven't invented V2? for CCS yet.

 

[Marktm]

Correct over than QC count.

We have a fair number of trial participants who are happily leaving the car plugged in for days/weeks at a time.

Even those commuting its typically only once per day which is the same as charging on route at a rapid.

The throughput figure in the BMS is the only real way to know.

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Mike;
If you recall, I've not been able to get a straight answer to any warranty issues with V2X here in the US - even after quoting their ops manual and asking for clarification.

If the BMS logging is the only recorded information on battery current in/out, is there any way to back into a V2X session by correlating QC timing with the current/voltage logging? Just guessing here!

I'd assume that QC count is only the times actually physically connected/disconnected at the charge port. - which for me would be once daily. Currently my connection count is a L2 connect every 3-4 days.

The next question - are all CHAdeMO ports after 2013 (if I recall) activated for V2X on the Leaf, or does Nissan have to use consult (or equivalent) to do so?
Thanks for any added information,
Mark

Note: It seems reasonable that "gentle" charging (discharging) based on optimal battery life parameters (called "smart charging"?) could result in longer battery life for many, even though the total anode/cathode "traffic" is greater when adding V2X to normal driving. For me, "normal driving" requires lots of very rapid anode/cathode "traffic" - great acceleration and regen!

 

[tom66]

I have a plug in hybrid Golf GTE and the battery has gone over 900 cycles by my reckoning. I avoid keeping it at 100% where possible although don't care so much about low SoC (though the car locks the lower 20% of the pack away.) I haven't noticed significant degradation despite the high cycle count. It appears to get at least 90% of the original capacity.

I think we are discovering that EV battery life is more down to chemistry and high SoC than anything else. Cycle life isn't as significant especially if the battery pack is cooled during charging. And the cooling is more important because it keeps the cells at a uniform temperature.