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[mrwilsn]

Has anyone tried a simple air scoop pointed at the motor?  It is tucked behind the battery pack real cozy. A simple plastic elbow might help.  It would hurt the overall air flow of the bike but in the summer might be worth it.  Just pop on or off depending on the season.  That Lightning has some nice features at least in theory.  Oil cooled motor case the acts as rear frame support.  Liquid cooled electronics and air cooled battery.  The Ego has air slots to both cool the battery and let air get back to the motor.  I think they have a patent on it though.

My gut tells me that if you want to scoop air towards the motor to cool things down in any kind of significant way you are going to need to do more than just redirect ambient air.  I think you would need to at least cool the air before blowing it on the motor and in that case I'm guessing it would be more efficient to liquid cool the motor directly...like lightning.

Making the motor part of the frame support like lightning would also be a good move for Zero.  They should also make the battery pack itself part of the frame support too.  I think a lot of weight could be shed by incorporating the motor and battery into the frame rather than building a big heavy frame strong enough to carry the weight of the two.

[MichaelJohn]

The SR frame weighs 23 pounds. With the modifications that would be necessary to incorporate the motor and the battery pack as integral frame pieces I doubt that there would be much potential weight saving.

[mrwilsn]

Zero could build a 20 kWh battery pack from their current cells, as mentioned previously. Or maybe they could use the LG cells powering the Bolt @ $145/kWh. I suppose Zero's costs are around $5k for its current 11 kWh pack, assembled. If they were able to get slightly higher pricing than GM, considering their lower volume - they could perhaps introduce a 20 kWh pack at the same cost as their current 11 kWh pack.

Luke Workman from Zero recently did an interview with Troy from motorcycle.com in which he mentions a woman, Dr. Ann Marie Sastry, who has created a prototype solid state battery that supposedly has twice the energy density of today's solutions and per an article in the Wall Street Journal they think they can hit a $100/kWh.  Luke says Zero hasn't been able to get any samples which isn't surprising.  With the investments the company, Sakti3, has from Dyson and GM, Zero isn't going to be first in line for these batteries.



Sakti3: The Next-Generation Battery Company You Need to Know About

Thus, I think the 2016 lineup is out of the question....maybe like 2018?  For this year I think we will see another incremental increase in energy density....which probably means a ZF14 without power tank.  Oddly, the energy density of the power tank didn't increase from 2014 to 2015 staying at 2.8kWh....maybe this year that will bump up too?  Maybe a 3.5kWh power tank to bring the total with power tank up to 17.5kWh for 2016?

Combined with another 30% increase from the addition of a fairing we could be looking at 108 mile range at 70MPH without a power tank and 135 mile range at 70MPH with a power tank.

If they do jump up to 20kWh I just hope they keep the center of gravity low....if they can do that then you could get up to 155 miles at 70MPH with a fairing....double the current range....which would be great but they also need to address quick charging or you will be waiting a long time to charge that sucker up.

[Doug S]

....I'm guessing it would be more efficient to liquid cool the motor directly...like lightning.

Liquid cooling is overrated. It has two chief advantages: 1) You can mount the radiator remotely, so it's easier to get in the airstream, and 2) It's trivial to add a thermostat, important for ICEs which need to get UP to operating temperature before they operate properly. (There are minor advantages too, like quieter operation and the ability to use engine heat to heat the cabin of the vehicle.) But as a rule, air-cooled systems are smaller, lighter, cheaper, less complex, more reliable, require less maintenance, and if properly designed, are every bit as effective as liquid cooling.

It's the last point where I think the Zero falls short. The heat sink fins on the motor are oriented side-to-side on the bike, meaning airflow needs to be sideways to effectively pull heat out of the fins, but that may be irrelevant since no attempt is made to direct air over the motor anyhow. The motor controller, by comparison, has front-to-back heat sink fins, located in a very good position for excellent airflow. It's also anodized black which helps a bit and looks cool besides.

I'm convinced that a simple design incorporating a scoop on one side to bring air into the motor area, and a jet of air on the other side to assist in evacuating air from that area, would massively improve the cooling of the motor. I'd be a little concerned about increasing the heat load to the battery pack by cooling the motor better, but that's monitored too and my guess is it would be okay.

[mrwilsn]

It's the last point where I think the Zero falls short. The heat sink fins on the motor are oriented side-to-side on the bike, meaning airflow needs to be sideways to effectively pull heat out of the fins, but that may be irrelevant since no attempt is made to direct air over the motor anyhow. The motor controller, by comparison, has front-to-back heat sink fins, located in a very good position for excellent airflow. It's also anodized black which helps a bit and looks cool besides.

I'm convinced that a simple design incorporating a scoop on one side to bring air into the motor area, and a jet of air on the other side to assist in evacuating air from that area, would massively improve the cooling of the motor. I'd be a little concerned about increasing the heat load to the battery pack by cooling the motor better, but that's monitored too and my guess is it would be okay.

I agree with pretty much everything you said....it just comes down to objectives.  If you just want a bike that is going to be limited to 100MPH and can sustain speeds of 70-80MPH for 100+ miles then you could probably get there with some improvements to air flow around the motor.  Thats all a lot of people want....which is why Zero definitely shouldn't get rid of the current S/DS/SR air cooled configuration.

I just think they need to add a liquid cooled bike to the lineup, because if you want a bike that makes for a greater commuter but can also be taken to track days on the weekend then you need something that is capable of 140MPH or better and I don't think you can do it with ambient air no matter how well designed.

But if Zero doesn't do it there is always the hot rodding route: .  At minute 8 they specifically discuss the attempts to improve air flow and the ultimate decision to go with liquid cooling.  Air alone under track conditions just doesn't cut it.

[protomech]

Thus, I think the 2016 lineup is out of the question....maybe like 2018?  For this year I think we will see another incremental increase in energy density....which probably means a ZF14 without power tank.  Oddly, the energy density of the power tank didn't increase from 2014 to 2015 staying at 2.8kWh....maybe this year that will bump up too?  Maybe a 3.5kWh power tank to bring the total with power tank up to 17.5kWh for 2016?

Zero's battery architecture since 2013 has been "bricks" of 28 cells in series. For 2013-2014 and for the 2015 FX bricks, these cells are 25 Ah high-power cells that can discharged at 8C (2.5 kWh per brick = 20 kW max power).

For the 2015 S/DS bikes, the relative power requirements are lower (2015 SR = 50 kW from 10 kWh = 5C) so they switched to using 27 Ah high-energy cells that don't need to be able to discharge as quickly (2.8 kWh per brick).

ZF5.7 FX = 33 kW from 5 kWh = 6.6C (high-power)
ZF8.5 S = 40 kW from 7.5 kWh = 5.3C (high-power, 2014)
ZF9.5 S = 40 kW from 8.3 kWh = 4.8C (high-energy, 2015)
ZF12.5 SR = 50 kW from 11 kWh = 4.5C (high-energy, 2015)

Zero could certainly build their power tank from the 27 Ah cells, which would give a small amount of extra energy. If they offer a power tank for 2016 they might do this.

Keep in mind for heating purposes as well that the fairing will significantly reduce the power requirements for highway travel, ie 2012 S = 12.8 kW for highway 70 mph, 2013-2015S = 9.8 kW for highway travel, faired Zero = 7 kW for highway travel. Less power required results in less heat produced .. though the fairing may also reduce air moving over the motor fins.

[mrwilsn]

For the 2015 S/DS bikes, the relative power requirements are lower (2015 SR = 50 kW from 10 kWh = 5C)...

I must be missing something...both 2014 and 2015 list max power at 50kW....how are the relative power requirements lower?

[protomech]

For the 2015 S/DS bikes, the relative power requirements are lower (2015 SR = 50 kW from 10 kWh = 5C)...

I must be missing something...both 2014 and 2015 list max power at 50kW....how are the relative power requirements lower?

2014 SR has a 10 kWh pack (4 bricks of 28 25 Ah cells .. I think this is actually 28 * 3.65V * 24.5 Ah * 4 = 10 kWh).
2015 SR has an 11 kWh pack (4 bricks of 28 27 Ah cells .. 28 * 3.65V * 27 Ah * 4 = 11 kWh).

Because the peak power draw is the same but the pack is larger, the relative power draw per cell is lower.

Similarly, with a fairing to decrease the highway power requirement and a much larger battery pack, the relative power draw will be much lower still. 50 kW peak / 20 kWh = 2.5C peak, 7 kW highway operation / 20 kWh = 0.35C.

Compare to highway 70 mph riding on 2012S ZF9 which was 12.8 kW / 7.9 kWh = 1.6C, or 2013S ZF11.4 which was 1.0C.

Numbers approximate but I hope you take my point.

[mrwilsn]

Numbers approximate but I hope you take my point.

Yeah, I'm following you.

If LG's batteries are as good as their marketing I hope Zero does put these in the 2016 bikes.  I couldn't help but laugh at these videos....This unrivaled technology is LG Chem's Worldwide First and Best Patented Technology! Haha

[wavelet]

....I'm guessing it would be more efficient to liquid cool the motor directly...like lightning.

Liquid cooling is overrated. It has two chief advantages: 1) You can mount the radiator remotely, so it's easier to get in the airstream, and 2) It's trivial to add a thermostat, important for ICEs which need to get UP to operating temperature before they operate properly. (There are minor advantages too, like quieter operation and the ability to use engine heat to heat the cabin of the vehicle.) But as a rule, air-cooled systems are smaller, lighter, cheaper, less complex, more reliable, require less maintenance, and if properly designed, are every bit as effective as liquid cooling.

I also greatly dislike liquid cooling on motorcycles as a rule -- it runs counter to the minimalist, simple-method-of-transportation aspect which is a major appeal of bikes for me.
Passive air-cooling is as simple as you can get -- no fragile radiator to get damaged, no reservoir to monitor, no hoses to replace. Even semi-passive systems, like the air/oil ones on some BMW Boxers and like my Suzuki Bandit had, work extremely well.
However, in an ICE, that means a wider operating temperature range  (ambient temperature can be anywhere from, say, -15°C to 45°C (5°F -o 115°F), which in turn means a less efficient engine.
I don't know how this applies to e-motorcycles, but it would certainly affect current battery chemistries; E-motorcycle are worse off to start with range-wise than BEV cars, so I'd expect they have less of a margin. And it certainly matters in car EVs -- the only common model without a cooling system, the LEAF, had lots of issues.

[Criticalmass]

Please bring back a purebred MX bike. Please?

[grmarks]

Going back to the original post, needing glasses to read these days, it's impossible to read the trip meter/other settings in this  section of the display.
So it would be nice if the numbers were as big as the battery SOC %.
Instead of putting the read outs one above the other, they could put them side by side, then they could be as big as the SOC %.
The heading could go beside the numbers in small print (same size they are now). Don't need to read the heading once selected.
Also the time could be a bit bigger too.

[Doug S]

However, in an ICE, that means a wider operating temperature range  (ambient temperature can be anywhere from, say, -15°C to 45°C (5°F -o 115°F), which in turn means a less efficient engine.

Actually, an air-cooling system is less effected by high ambient temperatures than a liquid cooling system. Heat transfer rate is proportional to the temperature difference between the two objects. In the case of an air-cooled engine, that's the difference between (say) a 50F airstream and a 400F cylinder head, or 350 degrees F. Now if the ambient temperature rises by 50F, you still have 300F temperature differential, and you've only lost 1/7th of your ability to shed heat.

But in a water-cooled engine, on the cooler day the temperature difference between 50F air and a 250F radiator is 200F, which goes down to 150F on a 100F day. You've lost 25% of your cooling ability.

It's counter-intuitive, but it's true....air-cooled engines suffer less on high-temperature days than water-cooled engines. That and lighter weight are the big reasons most small airplane engines are still air-cooled.

BTW I apologize for my part in hijacking this thread.

[Kocho]

It is not just the heat differential that matters but also the ability to cool. I don't know about engines, but for people, we lose it is said 25 *times* more heat in water than we do in air with the same temperature. That's why hypothermia occurs very fast (minutes) in cold water where we can survive hours in the same temperature air.

The only way to settle that is by looking at the math formulae for the heat exchange with liquids and gasses and plug-in several heat differential values and the correct heat absorption (heat capacity) values and see if the larger heat differential under normal operating temperatures with air will outweigh the higher heat absorption capacity of the coolant.

I'll give another empirical example of water cooling being a LOT more effective than air cooling, with *exactly* the same temperature differential and exactly the same cooling surfaces in both cases. I make home-made yogurt. The milk is boiled, so 212F. It needs to cool off to about 112F before I add the yogurt starter, which dies in hotter milk and does not work well in colder milk. If I leave the container with hot milk to cool in the air on the porch outside, it takes several hours to cool-off in 40F air. It takes just minutes in 40F tap water to cool off. Now, that might not be fair, because I replace the water that warms-up with colder water from the tap, where on a motorbike I would need to air-cool it with a radiator, and if that radiator is small, it won't be as effective as just getting new cold liquid in the system as I do with the milk. But the point of radiators is not just to get the air cooling exchange in a better place where there is more airflow, but to also have a larger cooling surface than the motor would allow. So they increase the heat exchange 3-ways: more cooling surface, better circulation, higher thermal capacity of the liquid.

[Erasmo]

You miss one very important factor, the temperature of the cooling medium.
Yes you lose heat faster in a liquid that is 10°C but the medium isn't 10°C but 80-90°C.