Molicel Tech (Stark Battery Thread)

[Karinshi]

This might be suitable for battery enthusiasts like us.

Well, I think many probably already knew this, but I wanted to create a thread dedicated to this Molicel technology, which Stark will likely be working with for a long time.

From what I've been researching, the new P60B cells have been available to the public since the end of August, after the testing period.
They belong to the same category of 21700 power cells; the capacity has increased from 5000mAh to 6000mAh and from 18Wh to 21.6Wh. The voltage is the same under nominal and charging conditions, but the discharge voltage has decreased from 2.5V to 1.8V. The charge current has also increased from 5.0A to 6.0A under standard conditions and from 25A to 30A at maximum.

Now I'll comment on what has disappointed me about this new version. A few months ago I read that the P60B cells had the same weight but more capacity (not true, I'll talk about this later). So, considering that the P50B cells have 260Wh/kg and weigh 70g each, the calculation would be to multiply 70g x 400 cells = 28kg, not counting the magnesium casing. Now you multiply 260Wh/kg x 28kg = 7,280kWh, which is the current capacity of the MX1.2, EX, and SM models. If we do the same calculation with the P60B cells, assuming they have the same weight of 70g but a higher gravimetric capacity of 280Wh/kg, the result would be 280Wh/kg x 28kg = 7,840kWh. But the problem is that the weight of the P60B cells has increased by 5g, so the calculation is no longer based on 28kg but on 30kg if we leave the battery with the same number of 400 cells.

This would give us a capacity of 280Wh/kg x 30kg = 8,400kWh, which would be very good but at the cost of 2kg more weight.

For some, this will be a problem, and for others, not. I don't see it as so relevant for the SM model, but it is for Enduro and motocross.
On other websites, not the official Molicel site (I'll attach a screenshot), they say that the P60B batteries have 288Wh/kg instead of 280Wh/kg. Here, we would have more leeway to achieve 288Wh/kg x 28kg = 8,064kWh by removing some cells instead of all 400. And that would be really good. Or, we could keep the extra 2kg and obtain 8,640kWh with the 400 cells. This configuration would work well with the new ALG model and the other Adventure projects that Stark has, where the weight can be increased without being a problem. They could even have greater capacity and weight; the limit will be set by Stark with his lightweight philosophy. I think Stark failed on not waiting for the P60B for the SM model, maybe they didnt want to wait for some more for so many reasons.


Molicel says their goal is to increase the capacity of their cells by 10% per year; let's hope they can achieve it. I can't wait to have at least 360 Wh/kg and, with the same 28 kg weight, reach 10,080 kWh of capacity. A DREAM!

SCREENSHOTS BELOW:




Web where it says 288wh/kg instead 280wh/kg, i think oficial Molicel info should be more accurate

 

[Beagle]

P60B weight 4 g more than P50B so that's 1.6 kg for the 400 cells pack.

What we know for sure is that Stark prototypes (ridden during their huge media days) had Molicel P42B (4.2 Ah), MX1.0 production bike has P45B (4.5 Ah) which increased capacity from 6.0 to 6.5 kWh.

Newest 7.2 kWh pack used in EX, MX1.2 and SM is made of 5.0 Ah cells, increasing capacity to 7.2 kg. We don't know who the supplier is, Wass just said that it wasn't Molicel anymore. Still wondering why they don't mention the supplier, it would be good publicity for them and they were happy to have Molicel stickers on their MX1.0 race bikes.

Main point is still relevant, in a handful of years 21700 cells went from 4.2 to 4.5, 5.0 and now 6.0 Ah, any e-motorcycle manufacturer effortlessly benefits from capacity increase every couple of years.

Next generation 400 cells pack using 6.0 Ah cells should be 8.6 kWh for a minimal weight penalty. An adventure bike could carry double pack for serious range with 17.2 kWh (about what Zero motorcycles make).

I guess for street motorcycles (not MX nor enduro) the big question is do you wanna go big (pack) or fast (charge)? Bikes with onboard CCS charger (like Honda WN7) should be able to charge really quick (though the charger is bulky).

 

[Karinshi]

oh yeah i knew about the p42b and p45b and i could swear i read that the new 7.2 pack was Molicel p50b, so everything I said isn't very relevant now... Molicel is top-of-the-line right now; I don't know what other brand Stark chose, but the cells must be practically identical to Molicel. I don't really care about the brand; what matters is the capacity and performance of the cells.
If they can reach about 8.6/9.0kwh (ideally 10kwh but that's at least 4 years away) with the same weight for the future EX 1.2 in 2 years, that could be amazing. Also to compensate the increise charging time due to the increased capacity, battery technology needs to reduce damage from fast charging so you can maintain the 2 hour charging time at least.

 

[Karinshi]

P60B weight 4 g more than P50B so that's 1.6 kg for the 400 cells pack.

What we know for sure is that Stark prototypes (ridden during their huge media days) had Molicel P42B (4.2 Ah), MX1.0 production bike has P45B (4.5 Ah) which increased capacity from 6.0 to 6.5 kWh.

Newest 7.2 kWh pack used in EX, MX1.2 and SM is made of 5.0 Ah cells, increasing capacity to 7.2 kg. We don't know who the supplier is, Wass just said that it wasn't Molicel anymore. Still wondering why they don't mention the supplier, it would be good publicity for them and they were happy to have Molicel stickers on their MX1.0 race bikes.

Main point is still relevant, in a handful of years 21700 cells went from 4.2 to 4.5, 5.0 and now 6.0 Ah, any e-motorcycle manufacturer effortlessly benefits from capacity increase every couple of years.

Next generation 400 cells pack using 6.0 Ah cells should be 8.6 kWh for a minimal weight penalty. An adventure bike could carry double pack for serious range with 17.2 kWh (about what Zero motorcycles make).

I guess for street motorcycles (not MX nor enduro) the big question is do you wanna go big (pack) or fast (charge)? Bikes with onboard CCS charger (like Honda WN7) should be able to charge really quick (though the charger is bulky).

also where Anton said that? do you have a Link? Thank you in advance

 

[Karinshi]

If we trust this AI response (attached below), it seems they created the cells themselves. It turns out they're now experts at making batteries too, surely with significant help from another company with expertise in the sector.

They'd better have developed 6.0Ah cells and higher for the future; they have a lot of competition.

Well, please excuse the inaccurate information, but you get the gist of it. We can continue discussing this topic if we ever get more information about Stark's proprietary battery and its future advancements.

 

[Chaconne]

Stark might be able to get better pricing from one of the mainland manufacturers. Molicel is based in Taiwan iirc.

 

[Theo]

Assuming the orginal MX 1.0 used P45B cells and assuming that Stark could go back to Molicel for some future models, here is a recap of the numbers; the numbers in orange font can also be found on the official datasheets linked below the table:

	P45B	P60B
nominal cell voltage	3.6	3.6
capacity (Ah)	4.500 Ah	6.000 Ah
capacity (Wh)	3.6 V * 4.5 Ah = 16.2 Wh	3.6 V * 6 Ah = 21.6 Wh
weight (g)	70	75
gravimetric energy density	16.2 Wh / 0.070 kg = 231 Wh/kg; on Molicel's datasheet 242 Wh/kg	21.6 Wh / 0.075 kg = 288 Wh/kg; on Molicel's datasheet 280 Wh/kg
continuous discharge current	45 A	60 A
max power from a 100S4P	100 * 3.6 V * 4 * 45 A = 65 kW = 88 hp	100 * 3.6 V * 4 * 60 A = 86 kW = 118 hp
capacity from a 100S4P	100 * 3.6 V * 4 * 4.5 Ah = 65 kWh	100 * 3.6 V * 4 * 6 Ah = 8.6 kWh
weight from a 100S4P	0.070 kg * 4 * 100 = 28 kg	0.070 kg * 4 * 100 = 30 kg

P45B datasheet
P60B datasheet

Now, let's set an equation to find out a new cell configuration to get 28 kg from P60B cells: with 4 rows in parallel: 0.075 kg * x = 28 kg / 4 → x = 7 kg / 0.075 kg = 93, so you could have a 93S4P setup.
The nominal voltage of the pack would become 335 V, that I wouldn't like since usually you want to get power from higher voltage and lower current so that there are less heat losses and you can also use thinner cables that save some weight. At that point, to get 30 kw which I think is a typical peak value for MX you would need 30.000 W / 335 V = 90 A (the pack could supply 60 A * 4 = 240 A), while with a 360 V battery you would need 83 A. Since the power lost to heat = I² * R, then the power lost to that heat would have increased by a factor of 90² / 83² = 1.18, which is a downgrade. I think that a low voltage is something that can be acceptable for a DIY conversion project, not form a premium bike. Calculating the R is not something that I feel like attempting at the moment. Anyways, can the motor, the inverter and the charger be used with those lower voltages?
Using a 3P configuration would mean 0.075 kg * x = 28 kg / 3 → x = 124, so 124S3P that would mean 446 V and 500 V at full charge; again, could they use the same motors, inverter and charger?
No worries for the capacity, since the gravimetric energy density would be improved, so for roughly 28 kg you would get 28 kg * 280 Wh / kg = 7.8 kWh in both cases.
Maybe one of the reasons for which they changed cells supplier is that they wanted to keep a similar voltage and that with the 3.6 V, cell weight and other specs that the Molicel cells have they couldn't find a configuration that suits their needs. The MX1.2 is rated to have a 420 V battery, while the technical specification for the 1.0 from their site is a voltage range from 250 V to 420 V, i guess depending on the SOC.