Half sized race battery?

[AgileMike]

Due to the range increases iI”m only using about 20pct battery in 7 lap race or 12 minute practice session. About 30 pct in 20 min moto session.
I would be very interested in purchasing a 1/2 size battery that is lighter and designed for mass centralization. Any other moto riders on the forum that would also purchase one?
The Stsrk already lays down so well and also feels very light in the air. I can’t imagine if it lost 10lbs and got even better mass centralization. I would pay 2k for this battery and I feel many other moto riders would as well.

 

[Beagle]

They already kinda did that for Thomas Do racing France SX tour in 2023. He said that for the last 2 rounds they got him a lighter battery.
They had probably removed 1 of the 4 parallel sets of 100 cells in series, so same voltage, maximum power reduced to 60 hp (reduced torque as well) and you save 7 kg. You're down at 4.9 kWh which was plenty for SX tour 10-12 min races.

 

[Erwin P]

Both smaller and bigger would sell i guess.

For myself a 20 minute moto race would go well over 50% used, buth that's on sand tracks. I would love a 10kW battery, even with weight disadvantages.

 

[Chaconne]

They already kinda did that for Thomas Do racing France SX tour in 2023. He said that for the last 2 rounds they got him a lighter battery.
They had probably removed 1 of the 4 parallel sets of 100 cells in series, so same voltage, maximum power reduced to 60 hp (reduced torque as well) and you save 7 kg. You're down at 4.9 kWh which was plenty for SX tour 10-12 min races.

Ya I was thinking the same thing. Wonder if you could DIY that?

 

[Chadx]

Both smaller and bigger would sell i guess.

For myself a 20 minute moto race would go well over 50% used, buth that's on sand tracks. I would love a 10kW battery, even with weight disadvantages.

Agreed! For my trail riding use, the range is the only thing keeping me from fulfilling my order. I'm used to 300+lb dual sports, so another 20lb of battery would still have me lighter and give me the range I need to do typical 40 to 50 miles trail rides without depleting the battery too far every ride (and leave some reserve for the occasional "wrong turn" for locked-gate-turn around). I was thinking 8kWh, but would be curious what a 10kWh would weight and cost. If they modded the Varg, or better yet, an similar but new offroad bike, to be fitted with a variety of battery packs, the buyer could pick and choose which battery size to buy that would fit their needs. Or even buy two (and larger and a small). Imagine a enduro version with the option to choose a 4kWh, 7kWh, or 10kWh battery. Nice.

 

[AL_V]

I assume Stark is already using a very energy dense type of battery cell, so the volume of the battery pack would also increase along with the weight.

 

[Erwin P]

I assume Stark is already using a very energy dense type of battery cell, so the volume of the battery pack would also increase along with the weight.

True, but that is to the buyer to decide if it's something they can live with.

I don't know if it's possible, but lets say the same battery but everywhere below the frame as wide (or a bit wider) as the frame. Apart from weight no real downsides and 8 to 9 ish or maybe even 10kW. That would be something my wallet might be able to bleed for depending on the price.

 

[Chadx]

I assume Stark is already using a very energy dense type of battery cell, so the volume of the battery pack would also increase along with the weight.

Yes, it's understood that the battery case would have to increase in size to accommodate more capacity. So whether they use the same frame and mounting point, like @Erwin P mentions, or has a slightly altered frame for an offroad/enduro-focused model separate from the Varg, the battery case size and weight would increase. Presumably, no one doing track days would want a bigger/heavier battery, so current Varg battery case could be used for the current battery size or a smaller capacity battery pack within the same battery case, for those that want a smaller/lighter Varg battery. And a new, larger battery case size would be developed for the a new enduro model. That large battery case could be configured with different capacities (two to four different capacities). Or perhaps only one or two different capacities in the larger battery case and then an adapter for the smaller Varg battery case and the Varg case could be had in two capacities. That would give the Varg buyers a choice of two capacities and the buyers of a new enduro model a total of four battery choices (two in the larger battery case and two in the Varg battery case).

Perhaps this new model with new frame (or slightly modefied Varg frame) could be offered in a couple trim levels; an enduro and a short range dual sport. As mentioned above, there would be two battery case sizes that would fit in this new model; A new large battery case and, with adapter, the Varg battery case. Large battery case could not be used in Varg but Varg battery case could be used in the new model. The big battery case could be up to 10kWh or more for an dual sport since they need a very large battery. Maybe even 12kWh (or 15kWh!). The large case could be had in 12kwh, 10kWh, 8kWh capacities and the Varg sized battery case in 6.6kWh and 4kWh.

 

[Mxpilot30]

Due to the range increases iI”m only using about 20pct battery in 7 lap race or 12 minute practice session. About 30 pct in 20 min moto session.
I would be very interested in purchasing a 1/2 size battery that is lighter and designed for mass centralization. Any other moto riders on the forum that would also purchase one?
The Stsrk already lays down so well and also feels very light in the air. I can’t imagine if it lost 10lbs and got even better mass centralization. I would pay 2k for this battery and I feel many other moto riders would as well.

I wondered the same thing. Just sell the same case but half the amount of batteries. It probably has something to do with the controller they would have to be some adjustment made but I'm not sure I hope they do this someday

 

[Mxpilot30]

I wondered the same thing. Just sell the same case but half the amount of batteries. It probably has something to do with the controller they would have to be some adjustment made but I'm not sure I hope they do this someday

 

[Theo]

I wish it was possible to have modular batteries like it is possible to have modular power stations.
We could have a 9 kwh battery split into three modules having 3 kwh capacity each: when you do motocross, you use one 3 kwh module while another one is under charge in the parking lot, ready to be swapped; if it's not enough, you use 2 X 3 kwh modules. If you need more range for enduro, then you will use all three modules.

 

[Beagle]

Zero motorcycles is offering up to 17 kWh batteries (upgradable to 21 kWh!) on their street bikes.
Obviously we're talking street bikes over 200 kg, just to say that there is some margin to go for Stark for their road models.

 

[Erwin P]

Presumably, no one doing track days would want a bigger/heavier battery,

I think you're wrong.

The really fast guys out here drain them in 20-25 minutes while their races take 30 minutes. So no Starks racing in higher regions here.

The battery last me about 40 minutes, but i wouldn't want it smaller since charging otherwise won't keep up with my use over the day.

 

[Chadx]

I think you're wrong [about "Presumably, no one doing track days would want a bigger/heavier battery,"]

The really fast guys out here drain them in 20-25 minutes while their races take 30 minutes. So no Starks racing in higher regions here.

The battery last me about 40 minutes, but i wouldn't want it smaller since charging otherwise won't keep up with my use over the day.

Yeah, I agree there are motocross riders that need more battery capacity (range) than the Vargs current battery. I guess my point was they may WANT a higher capacity battery, but are they willing to live with the added weight? The extra weight might be a deal breaker where the trail and enduro riders are less weight sensitive. Trail riders need more kWh for range/capacity but are less concerned about overall weight than motocross users. For motorcross riders, how much extra weight are they willing to live with vs it making it not worth going battery-electric? 20 more pounds? 30? 40? I'm not a track rider, so that is a real questions as I have no idea. They just talk about weight, weight, weight and many already say the Varg is too heavy to consider. Maybe that opinion changes after riding and getting a feel for how the bike carries the weight, but what is that limit? I'd ride a battery-electric Stark trail bike that was 300lbs, or maybe more, without batting an eye. I don't know that a motorcross rider would say the same. Interested in hearing more from those riders.

 

[Erwin P]

Mostly Keybord riders complain about weight.
The high level MX riders ride what they are fastest on. If that happens to weigh 20lb heavy'er than a 450 so be it.

 

[Number Six]

Early on I had an email conversation going with an EV powertrain engineer & expressed the same thought of reducing battery mass for a lower OA weight & reduced range.
I believe the Varg battery is about 77 lbs, a 30 % mass reduction would likely be about 18-20 lbs lighter as some of that 77 is the case, But a 240-ish LB Varg would be terrific, yes ?

Apparently the issue throwing water on that premise is a perennial EV nemesis & everyone's favorite uncle ; heat.
I was informed that a 30% reduction in battery mass ( less cells ) results in double the heat load & corresponding temperature increases for the same available power output as in the full capacity battery.
So .. either the power gets reduced ( thats no fun ) or thermal limiting enters the chat once temps rise to a given point, which they will, & quickly on an MX track.
Now the Varg has the same Achilles heel as the Alta did all those years ago ...

File under ; there's no free lunch.

 

[Erwin P]

Double the heat would translate in roughly half the power? 40hp might do for some people.

 

[Beagle]

They made it much simpler, just removing 1/4 of the cells keeping identical voltage, thermal management is identical, you lose 1/4 of power (so you "only" get 60 hp), lose 1/4 range, lose 7 kg (Molicel P45b cells weight 70 g each).

Going from OP demand, with half the cells you get 40 hp, half the range and save 14 kg.

I wonder what they run for indoor enduro 7 min races, range would be fine but they likely need a bit more power/torque/pop than this half battery setup.

 

[Number Six]

The 60HP Varg I test rode really needed to be at 50 HP or thereabouts to be able to reliably & instantly loft the front over things similar as an ICE bike with a clutch.
It was nicer to ride at around 40-45 HP, but just didn't have quite enough pop to stand the bike up at a moments notice at that level, for me at least.
It's likely that a rider with better timing & technique ( read ; talent ) than I could manage with just a 40-45 HP setting.

What's most interesting & encouraging with all the recent development of bikes like the Stark, Ultra Bee, soon-to-be Dust & others is that now that there's lots of these being used for differing disciplines, their limitations & any deficiencies for specific applications are becoming well documented & understood, which bodes well for the next generation of machines to follow.

 

[fsfs]

The 60HP Varg I test rode really needed to be at 50 HP or thereabouts to be able to reliably & instantly loft the front over things similar as an ICE bike with a clutch.
It was nicer to ride at around 40-45 HP, but just didn't have quite enough pop to stand the bike up at a moments notice at that level, for me at least.
It's likely that a rider with better timing & technique ( read ; talent ) than I could manage with just a 40-45 HP setting.

What's most interesting & encouraging with all the recent development of bikes like the Stark, Ultra Bee, soon-to-be Dust & others is that now that there's lots of these being used for differing disciplines, their limitations & any deficiencies for specific applications are becoming well documented & understood, which bodes well for the next generation of machines to follow.

Let me try and explain it this way. On the Varg the HP setting really sets the motor current limit; at RPM below about 7K this is actually more of a torque limit. Of course, HP is proportional to torque so it is called a "HP" instead of Newton meters. I apologize in advance for the math but here it is.

Battery_Voltage * Battery_Current = Motor_Voltage * Motor_Current

Also remember that Motor_Current corresponds to torque and Motor_Voltage corresponds to RPM.

This holds as long as we are not in field weakening, so below roughly 7K RPM, or about half the Varg's top speed.

So using throttle at low speed to lift the front doesn't require much power because Motor_Voltage is low (because Motor RPM is low). A half pack or 3/4ths pack would have no problem lofting the front end. Where you get into issues is with range and torque at high speed.

Also, heat is proportional to current squared times resistance. So 80HP makes 1.77 the battery heat of 60HP (if you are actually using that power).

In short, with a half or 3/4 pack I don't see a battery heat issue or torque limitation issue with enduro or single track. Range is the biggest issue.