State of Charge - 4MJ

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Re: State of Charge - 4MJ

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So you are going to continue to make statements like "the ES can only discharge 4 MJ per lap"?

The only rule that mentions 4 MJ/lap is the energy limit from ES to the MGUK.

ES>H and H>ES are both unlimited power and unlimited energy. The only restriction is the "state of charge" rule which means the ES must remain in a 4 MJ band. There is no limit to how much, how fast or how often the state of charge moves within that band.
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Re: State of Charge - 4MJ

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saviour stivala wrote:
Tue Jul 31, 2018 2:39 am
I can see and fully understand your reasoning and thanks for trying to explain but am sorry I cannot agree with all that.
Why can't you agree with it given that it does compile with the technical regulations?
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Re: State of Charge - 4MJ

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Sevach wrote:
Thu Jul 26, 2018 3:45 am
The 160 hp for 33s was the press needing to put a number that the average joe could understand.

Even forgetting the MGUH factor cars have highly complex deployment strategies, gear, speed and even timing/sequencing dependent(last year Alonso "broke" his car programming by going full throttle into Pouhon).
Aka you don't need full power in 2nd you'll just waste it spinning the tires.

Why the Mercedes pr department still uses the 33s figure?
Because there's no limit to the MGUH, it's not in their best interests to reveal just how effective their system is.


Even keeping their cards close to their chest you can see little tidbits of truth when a real tech guy speaks.
Here's Andy Cowell
https://www.autosport.com/f1/news/13594 ... --mercedes

60% of the energy used comes from the MGUH(which might be underselling it) and the Ferrari system is suppousedly better than that.
Yes, you can see little tidbits of truth when a real tech guy speaks. here's Andy Cowell. Well those "little tidbits of truth depends on who quotes him, when I did there were no truths in what he said.

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Re: State of Charge - 4MJ

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Blaze1 wrote:
Mon Aug 06, 2018 6:16 am
saviour stivala wrote:
Tue Jul 31, 2018 2:39 am
I can see and fully understand your reasoning and thanks for trying to explain but am sorry I cannot agree with all that.
Why can't you agree with it given that it does compile with the technical regulations?
Because "state of charge refers to the difference between lowest charge and highest charge" and this state of charge will reset each time the strart finish line is passed.

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turbof1
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Re: State of Charge - 4MJ

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saviour stivala wrote:
Mon Aug 06, 2018 8:52 am
Blaze1 wrote:
Mon Aug 06, 2018 6:16 am
saviour stivala wrote:
Tue Jul 31, 2018 2:39 am
I can see and fully understand your reasoning and thanks for trying to explain but am sorry I cannot agree with all that.
Why can't you agree with it given that it does compile with the technical regulations?
Because "state of charge refers to the difference between lowest charge and highest charge" and this state of charge will reset each time the strart finish line is passed.
No, it will not reset. The difference counts I believe for the whole session, so for instance between start and finish of qualifying, or between start and finish of the race:
"the difference between the maximum and minimum state of charge of the ES may not exceed 4MJ at any time the car is on track"
FIA F1 2018 Technical Regulations Appendix 3 Power Unit Energy Flow

A possible loophole here is the wording "on track". Does for instance going into the pits counts as being on track or not, and if not can we view the SoC being 'reset'. I think the "at any time"' part leaves for little room when the car is effectively deemed on track and thus can't be viewed as lap per lap.

For the record, I don't deem Andy Cowell as a reliable source per se, because it's not in his and his team's interest to always give away the truth. What he gives, can be interesting, but everybody should always keep in the back of their heads what he says can be misleading.
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saviour stivala
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Re: State of Charge - 4MJ

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turbof1 wrote:
Mon Aug 06, 2018 9:16 am
saviour stivala wrote:
Mon Aug 06, 2018 8:52 am
Blaze1 wrote:
Mon Aug 06, 2018 6:16 am

Why can't you agree with it given that it does compile with the technical regulations?
Because "state of charge refers to the difference between lowest charge and highest charge" and this state of charge will reset each time the strart finish line is passed.
No, it will not reset. The difference counts I believe for the whole session, so for instance between start and finish of qualifying, or between start and finish of the race:
"the difference between the maximum and minimum state of charge of the ES may not exceed 4MJ at any time the car is on track"
FIA F1 2018 Technical Regulations Appendix 3 Power Unit Energy Flow

A possible loophole here is the wording "on track". Does for instance going into the pits counts as being on track or not, and if not can we view the SoC being 'reset'. I think the "at any time"' part leaves for little room when the car is effectively deemed on track and thus can't be viewed as lap per lap.

For the record, I don't deem Andy Cowell as a reliable source per se, because it's not in his and his team's interest to always give away the truth. What he gives, can be interesting, but everybody should always keep in the back of their heads what he says can be misleading.
Yes, understand and agree, but my point was it depends on who quotes him, when I did he sure wasn't.

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Re: State of Charge - 4MJ

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When I said state of charge will re-set each time the car crosses the start/finish line I meant “the flow of max 4MJ per lap from ES to K will re-set every time the car crosses the start/finish line.

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turbof1
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Re: State of Charge - 4MJ

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saviour stivala wrote:
Mon Aug 06, 2018 11:49 am
When I said state of charge will re-set each time the car crosses the start/finish line I meant “the flow of max 4MJ per lap from ES to K will re-set every time the car crosses the start/finish line.
Yes that is correct. To be fair, it can be confusing with both the 4MJ ES to MGU-K limit and the 4MJ SoC.
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gruntguru
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Re: State of Charge - 4MJ

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Perhaps the easiest way to view the SOC rule is this. "The battery cannot store more than 4 MJ of energy."

The SOC rule allows teams to use a bigger battery but only use 4 MJ of its total capacity. This allows them to avoid operating in inefficient or risky areas like "very low" or "very high" charge states. It is also necessary to handle the charge/discharge power levels required - up to approximately 200 kW. Lastly it allows some margin when battery performance declines through age or environmental factors. That 4 MJ battery can quickly become something less.
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Re: State of Charge - 4MJ

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gruntguru wrote:
Tue Aug 07, 2018 4:25 am
Perhaps the easiest way to view the SOC rule is this. "The battery cannot store more than 4 MJ of energy."

The SOC rule allows teams to use a bigger battery but only use 4 MJ of its total capacity. This allows them to avoid operating in inefficient or risky areas like "very low" or "very high" charge states. It is also necessary to handle the charge/discharge power levels required - up to approximately 200 kW. Lastly it allows some margin when battery performance declines through age or environmental factors. That 4 MJ battery can quickly become something less.
Or perhaps, "The battery cannot store more than 4MJ of usable energy."?
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henry
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Re: State of Charge - 4MJ

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I have made the assumption that the SOC is monitored by the ES sensor sending reports of energy flow which are integrated by the monitoring software to ensure that the difference between high and low is never greater than 4MJ. What this mechanism ignores is the efficiency of the charge and discharge. It doesn’t care. However my limited understanding of batteries suggests that this might have a significant effect on the choice of battery capacity.

As an example consider a fully charged battery which discharges 4MJ through the sensor. If the discharge efficiency is 99% the actual, as opposed to measured, reduction in SOC will be 4.04 MJ.

Similarly if the ES sensor then records a charge of 4MJ , but the battery will increase by 3.96 MJ.

The 0.08 MJ will be turned into heat and will be removed by the cooling system.

If on typical race laps the ES sensor sees 2MJ in and out per lap, in a 60 lap race that’s 240MJ and at 99% efficiency that’s a “reduction” of battery capacity of 2.4MJ.

So if the ES started the race with an upper limit of 12MJ it might end at 9.6.

When I went looking for efficiencies I could only find figures at low charge/discharge rates. Is 99% a reasonable figure for the sort of rates experienced by the ES? At 98% efficiency a 12MJ upper threshold start, 8MJ lower, could end with the lower threshold at 3.2 which is close to the 25% limit below which it is suggested you shouldn’t take a battery.
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Re: State of Charge - 4MJ

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henry wrote:
Tue Aug 07, 2018 10:52 pm
...
When I went looking for efficiencies I could only find figures at low charge/discharge rates. Is 99% a reasonable figure for the sort of rates experienced by the ES? At 98% efficiency a 12MJ upper threshold start, 8MJ lower, could end with the lower threshold at 3.2 which is close to the 25% limit below which it is suggested you shouldn’t take a battery.
afaik efficiencies as high as you stated is only achievable when charging up to 70% SOC. Usually constant current and is typically called stage1.
Image
And most likely it will be lower at higher charging/discharging rates due to parasitic losses. At least according to Kokam. Image
At higher SOC the efficiency becomes less and less until it reaches 0%.
Wikipedia for example states a charging, discharging efficiency of 80-90%, but doesn't state for which SOC.
Last edited by rscsr on Wed Aug 08, 2018 12:06 pm, edited 1 time in total.

saviour stivala
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Re: State of Charge - 4MJ

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Blaze1 wrote:
Tue Aug 07, 2018 7:15 pm
gruntguru wrote:
Tue Aug 07, 2018 4:25 am
Perhaps the easiest way to view the SOC rule is this. "The battery cannot store more than 4 MJ of energy."

The SOC rule allows teams to use a bigger battery but only use 4 MJ of its total capacity. This allows them to avoid operating in inefficient or risky areas like "very low" or "very high" charge states. It is also necessary to handle the charge/discharge power levels required - up to approximately 200 kW. Lastly it allows some margin when battery performance declines through age or environmental factors. That 4 MJ battery can quickly become something less.
Or perhaps, "The battery cannot store more than 4MJ of usable energy."?
you are risking upsetting the apple cart.

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Re: State of Charge - 4MJ

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henry wrote:
Tue Aug 07, 2018 10:52 pm
I have made the assumption that the SOC is monitored by the ES sensor sending reports of energy flow which are integrated by the monitoring software to ensure that the difference between high and low is never greater than 4MJ. What this mechanism ignores is the efficiency of the charge and discharge. It doesn’t care.
Interesting point!
Is there another rule to compansate for this, like there is for deployment?

Anyone knows what battery cells could f1 teams be using?

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henry
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Re: State of Charge - 4MJ

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rscsr wrote:
Wed Aug 08, 2018 6:01 am
henry wrote:
Tue Aug 07, 2018 10:52 pm
...
When I went looking for efficiencies I could only find figures at low charge/discharge rates. Is 99% a reasonable figure for the sort of rates experienced by the ES? At 98% efficiency a 12MJ upper threshold start, 8MJ lower, could end with the lower threshold at 3.2 which is close to the 25% limit below which it is suggested you shouldn’t take a battery.
afaik efficiencies as high as you stated is only achievable when charging up to 70% SOC. Usually constant current and is typically called stage1.
https://batteryuniversity.com/index.php ... _batteries
And most likely it will be lower at higher charging/discharging rates due to parasitic losses. At least according to Kokam. http://kokam.com/cell/
At higher SOC the efficiency becomes less and less until it reaches 0%.
Wikipedia for example states a charging, discharging efficiency of 80-90%, but doesn't state for which SOC.
Thanks for that. I don’t know much about batteries, obvious I know. My interest is in how the regulations work and their implications for the design, implementation and exploitation of the PUs.

To understand at the chart in your post I need to know the C rate. If I assume the max capacity of an ES battery pack as 20MJ then 1C would be at a discharge rate of 5.5kW. Since the ES charge/discharge rates probably range between 60kW up to maybe 200KW that would imply C values of 11 to 36.

At these values of C the efficiencies will be below 90%.

So my assumption that SOC is determined by the integral of energy in, energy out of the ES sensor must be wrong. Or my understanding of the cumulative effect of losses is wrong. If it’s the former I wonder how they do monitor SOC?

Either way these efficiency figures make using the ES look like a necessary evil rather than the best thing to do.

For instance a round trip of MGU-K > ES > MGU-K at 120kW ( 22C) would result in 1MJ recovered becoming maybe 0.8MJ or less deployed.

This also informs the issue of cooling with maybe 2kW plus needed for the ES.
Fortune favours the prepared; she has no favourites and takes no sides.
Truth is confirmed by inspection and delay; falsehood by haste and uncertainty : Tacitus