Ferrari Power Unit Hardware & Software

[Dr. Acula]

3) This has me thinking, could the suspected Ferrari dual battery have two types of cell technology. Maybe the Power Cell for the MGU-K where exactly 120 kW charge / discharge is needed, and another for the MGU-H which would be sized based on its use scenario?

Well, the problem is that the rules only allow the use of 2 ES per season and they also need to be homologated by the FIA, so you can't change things after you used them once.
So i don't think this is very likely.

[saviour stivala]

Yes the rules says only 2 ES for this season (year) and yes ES must be homologated which means once homologated no changes after use and it also means that once homologated it is legal.
From what was said by one manufacturer on average a battery pack is fully charged and discharged over 70 times during each GP. Which means that if over a 21 GP season 2 battery packs are used each one would have been fully charged and discharged 385 time, and if a 12mj capacity is used each cycle would have been 33.3percent of total capacity.

[henry]

So state of the art for F1 is likely to be rather more than 12MJ.

"Energy density: up to 385 Wh/l and 180 Wh/kg" - Saft
So 13MJ for 20kg battery

A good recent article (http://www.powersourcesconference.com/P ... s/21-3.pdf) on Saft pouch type battery testing. Figure 1 shows the tradeoff between specific energy and power which may greatly effect battery performance. Of note is the last page in the article where it talks about solid state batteries. This could be (or maybe already is) technology F1 will adopt.

That’s an excellent paper. Many interesting facts.

A factor that would influence the choice of weight for the battery pack is the difference in c-rate for different capacities.

For a 20kg, 13MJ battery C=1 @ 3.6kW
For a 25kg, 16.25MJ battery C=1 @ 4.5kW

Running at lower c-rate would, if I read the Saft data correctly, improve the efficiency of the charge/discharge cycles. At any point in the race the combination of higher SOC and lower c-rate would give higher power density. This would reduce cooling requirements with an indirect performance advantage.

[subcritical71]

3) This has me thinking, could the suspected Ferrari dual battery have two types of cell technology. Maybe the Power Cell for the MGU-K where exactly 120 kW charge / discharge is needed, and another for the MGU-H which would be sized based on its use scenario?

Well, the problem is that the rules only allow the use of 2 ES per season and they also need to be homologated by the FIA, so you can't change things after you used them once.
So i don't think this is very likely.

I was not implying they changed anything, but they could design the battery and therefore have the battery homologated in this type of configuration.

[Dr. Acula]

I was not implying they changed anything, but they could design the battery and therefore have the battery homologated in this type of configuration.

Sure, but then you are stuck with only 2 specific designs. Are there only 2 specific scenarios? I don't think so. How the battery is used is very track specific. Sure, some tracks will have very similiar requirement to each other, but others don't and i don't think only 2 desings would be enough to give you an optimal solution for each track.
With 4 ES per season i think this idea could be realistic, but not with 2 ES per season.

[subcritical71]

I was not implying they changed anything, but they could design the battery and therefore have the battery homologated in this type of configuration.

Sure, but then you are stuck with only 2 specific designs. Are there only 2 specific scenarios? I don't think so. How the battery is used is very track specific. Sure, some tracks will have very similiar requirement to each other, but others don't and i don't think only 2 desings would be enough to give you an optimal solution for each track.
With 4 ES per season i think this idea could be realistic, but not with 2 ES per season.

Maybe a misunderstanding.... in a single ES I would propose 2 different cell technologies. One technology optimized for the MGU-K (+/- 120 kW) and the other technology optimized for the MGU-H. As the Saft article showed there are different Li-Ion cells available for different use scenarios (power vs energy usage).

[henry]

I was not implying they changed anything, but they could design the battery and therefore have the battery homologated in this type of configuration.

Sure, but then you are stuck with only 2 specific designs. Are there only 2 specific scenarios? I don't think so. How the battery is used is very track specific. Sure, some tracks will have very similiar requirement to each other, but others don't and i don't think only 2 desings would be enough to give you an optimal solution for each track.
With 4 ES per season i think this idea could be realistic, but not with 2 ES per season.

Maybe a misunderstanding.... in a single ES I would propose 2 different cell technologies. One technology optimized for the MGU-K (+/- 120 kW) and the other technology optimized for the MGU-H. As the Saft article showed there are different Li-Ion cells available for different use scenarios (power vs energy usage).

I think it might be worth looking at the duty cycles for the ES. I think it might look like:

Discharge from highest to lowest:

Turbo anti lag. 180kW for a couple of tenths of seconds exiting slow corners all to the H
Electric Supercharge. 180kW for a few seconds a lap, more during qualifying 120 to K, 60 to H
Sustain plus mode. 60kW to the K to augment the H, applied for as much as 60 seconds a lap


Charge from highest to lowest

Coast plus plus. 180kW for a second or two at the end of straights, 120kW from the K, 60 from the H, I think Ferrari do this and Mercedes don’t.
Extra Harvest. 120kW or more from the H (Honda specific?) for a few seconds at the end of straights
Braking. 120kW from the K during the braking phase, 8 to 20 seconds depending on track
Coast plus. 60kW from the H at the end of straights, the ICE provides all the motive power
Part throttle, up to 120kW from the K. Used from 0 torque demand up to, say, 80% demand

Rather than separating by H and K, which I don’t think have independent connections to the ES, Ferrari might have their two batteries optimised for two groups of duty cycles, say 120 and above and up to say 90. Not much different from your numbers but organised on a different principle. The former could be smaller capacity and they might even move charge between them after or before the high duty cycle spikes on the track.

[subcritical71]

Rather than separating by H and K, which I don’t think have independent connections to the ES, Ferrari might have their two batteries optimised for two groups of duty cycles, say 120 and above and up to say 90. Not much different from your numbers but organised on a different principle. The former could be smaller capacity and they might even move charge between them after or before the high duty cycle spikes on the track.

Yes! I hadn't considered the transfer between cell banks. Its an interesting idea and makes sense since between the heavy MGU-K usage there could be a relatively longer period of time in which a lower transfer rate (bank to bank) would not be performance limiting.

[sosic2121]

Rather than separating by H and K, which I don’t think have independent connections to the ES, Ferrari might have their two batteries optimised for two groups of duty cycles, say 120 and above and up to say 90. Not much different from your numbers but organised on a different principle. The former could be smaller capacity and they might even move charge between them after or before the high duty cycle spikes on the track.

Yes! I hadn't considered the transfer between cell banks. Its an interesting idea and makes sense since between the heavy MGU-K usage there could be a relatively longer period of time in which a lower transfer rate (bank to bank) would not be performance limiting.

I considered that kind of battery optimisation before, but I don't think it's viable.

[henry]

Rather than separating by H and K, which I don’t think have independent connections to the ES, Ferrari might have their two batteries optimised for two groups of duty cycles, say 120 and above and up to say 90. Not much different from your numbers but organised on a different principle. The former could be smaller capacity and they might even move charge between them after or before the high duty cycle spikes on the track.

Yes! I hadn't considered the transfer between cell banks. Its an interesting idea and makes sense since between the heavy MGU-K usage there could be a relatively longer period of time in which a lower transfer rate (bank to bank) would not be performance limiting.

I considered that kind of battery optimisation before, but I don't think it's viable.

Care to say why you don’t think it’s viable? I don’t know much about batteries and I’d like to know a little more.

I think I owe you an apology. Back when AMUS published some end of straight data for Mercedes and Ferrari you and I had a brief discussion of what it revealed. I didn’t follow through on it, so now I will because I think it’s relevant now.

When I simulated the the data I found that I could match the figures by having the Mercedes switch to harvest from the MGU-H from the beginning of the data and the Ferrari continuing to use the MGU-H to drive the MGU-K up to a higher speed and then harvesting from both the H and K. They both harvested a similar amount and the time to cover the distance was only about 0.01 seconds quicker for the Ferrari.

One could suggest from this that Ferrari is happy to harvest at a higher rate than Mercedes. This might suggest that their battery is configured to operate efficiently at higher charge rates.

[dans79]

Yes! I hadn't considered the transfer between cell banks. Its an interesting idea and makes sense since between the heavy MGU-K usage there could be a relatively longer period of time in which a lower transfer rate (bank to bank) would not be performance limiting.

I considered that kind of battery optimisation before, but I don't think it's viable.

Care to say why you don’t think it’s viable? I don’t know much about batteries and I’d like to know a little more.

The chemical reactions inside the cells are not 100% efficient, and you will also loose energy during the transfer do to resistance.

[henry]

I considered that kind of battery optimisation before, but I don't think it's viable.

Care to say why you don’t think it’s viable? I don’t know much about batteries and I’d like to know a little more.

The chemical reactions inside the cells are not 100% efficient, and you will all loose energy during the transfer do to resistance.

Yes I know that. The question is which chemistries, organisation and operation minimise these losses.

Is it possible that a battery optimised to accept charge at a high c-rate then transferring to a battery optimised for low c-rate will lose less energy than a single battery optimised for one or the other or neither?

The energy loss thing is an interesting issue. If every lap the ES processes 4MJ that’s 240MJ over a 60 lap race. Energy loss of 1% means that 2.4MJ went into the ES and didn't come out. This can be “recovered” by allowing the ceiling charge in the ES to decrease. So if it started at 16MJ it will end the race at 13.6. There will be a loss rate at which replacing the losses from energy stored at the beginning of the race is not possible.

I’m not sure how much difference this would make but it makes me think that the ES configuration decisions are trickier than I imagined when I knew even less about batteries than I do now.

[dans79]

Is it possible that a battery optimised to accept charge at a high c-rate then transferring to a battery optimised for low c-rate will lose less energy than a single battery optimised for one or the other or neither?

Charging at a higher rate and then transferring it, would most likely be worse, because charging at a higher rate generates more heat. So you have to add that on top of the loss you get form the transfer, that ultimately turns into heat as well.

[Brake Horse Power]

What if it is a 2 piece battery because part one is saft pouch type lithium battery. Part 2 is an extremely efficiënt supercap which is able to be instantly charged and uncharged. The abity to react quickly very efficient could make sense when combined with the 20hz MGU-H generating. Energy density is lower than lithium tough, so if the supercap is flooding this energy will need to go to the lithium battery.

Skeletontech actually mentions supercaps is very suitable for KERS applications.
https://www.skeletontech.com/high-end

[godlameroso]

You're also limited to 1,000 volts, although no one is probably anywhere near that, higher voltage would bring it's own challenges regarding insulation and a host of other things I'm ignorant about, but would be the most straightforward way to reduce losses as far as energy transfer.