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[dukecola]

Also, don't forget about wind chill.

For those of us that used to suffer carb-icing on our older ICE bikes, it's one thing to be warm at standstill, but moving through cold air reduces the temps even further. Might have been 20F at rest, but certainly moving through the air would have made the bike colder.

Wind chill only effects exposed skin, not inanimate objects.  If temp is 20 degrees, an object will be 20 degrees regardless of wind.

[Crilly]

Ya, wind chill is what the temp well feel like if you stand out side naked at that temp with no wind.So if you got a know what the wind chill is, you are going to look pretty stupid.

[Crissa]

Because of wind sheer, it does continue to work on static objects in the wind to be slightly lower than the average temperature of the air because the heat that's in air isn't evenly spread and ugh... I haven't done the math on this in thirty years x-x

So yes, if air continues to pummel a surface with edges it will depart with more heat than it arrived in as it's pushed away.  At the macro level this is basically a friction effect and at the micro level it's... Called something else.  At enough pressure, the collisions impart more on the edge, and the gas motion is converted to heat, at lower pressures and velocities, the gas molecules absorb more energy than they impart.

Aircraft experience this; if they go fast enough, the leading edges heat up (like a spacecraft re-entering the atmosphere) and at slow speeds near but nto quite freezing they can create ice (tho that's because our air contains water molecules which fall in and out of being a gas depending on temperature and relative air pressure).

Bleah.

-Crissa

[ESokoloff]

Because of wind sheer, it does continue to work on static objects in the wind to be slightly lower than the average temperature of the air because the heat that's in air isn't evenly spread and ugh... I haven't done the math on this in thirty years x-x

So yes, if air continues to pummel a surface with edges it will depart with more heat than it arrived in as it's pushed away.  At the macro level this is basically a friction effect and at the micro level it's... Called something else.  At enough pressure, the collisions impart more on the edge, and the gas motion is converted to heat, at lower pressures and velocities, the gas molecules absorb more energy than they impart.

Aircraft experience this; if they go fast enough, the leading edges heat up (like a spacecraft re-entering the atmosphere) and at slow speeds near but nto quite freezing they can create ice (tho that's because our air contains water molecules which fall in and out of being a gas depending on temperature and relative air pressure).

Bleah.

-Crissa

I'm not sure that some of this is correct.

Wind shear is not at play here.

Temperature differential is needed for heat to flow (Heat travels from high to low).
The greater the differential, the greater the transfer.
No differential, no transfer of heat regardless of the wind or speed of vehicles in this discussion.

If there is a temperature differential, the greater the number of molecules that come in contact with the surface (wind speed), the greater the transfer of heat.

In order to have air speed effecting surface's of a vehicle (rise in temperature), speeds have to be exponentially greater then the speed of the vehicles in this discussion.

[SBK74]

Wind chill or not, bottom line is that the Zero SR/F heats up the auxiliary 12V battery when it's below freezing temperatures  and during this warming up, the bike remains disabled for 1-15 minutes. So the bike of the Topic Starter responds as described in the small print of the manual. The Topic starter's asks if this is a design flaw? Considered the fact that the main battery is still working at much lower temperatures, I find it strange that the 12V battery is already limiting useability just below freezing.

[Crissa]

We don't have the logs.  We can't know which temperature out of bounds caused their bike to shut down.

-Crissa

And... I'm sorry heat flow isn't as simple as middle school science implied.  As long as there's outside energy - the wind in this instance - heat can flow in different directions.

[ESokoloff]

And... I'm sorry heat flow isn't as simple as middle school science implied.  As long as there's outside energy - the wind in this instance - heat can flow in different directions.

The heat transfer coefficient or film coefficient, or film effectiveness, in thermodynamics and in mechanics is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ?T):

https://en.wikipedia.org/wiki/Heat_transfer_coefficient

Without Delta T there is no transfer of energy.

[ESokoloff]

..........
Is this just a design flaw on the bikes, or something specifically borked with my 12V battery? I'll ask the dealer soon too ..........

Sounds to me like it's a design limitation as apposed to a flaw but the dealer should be able to find out.
Might have to add additional heater(s) to accommodate these extreme temperatures.

Could you plug the bike into a 120v A/C plug while the bike is parked during the day?
Should be easy enough to add a silicone heater in a strategic location(s) so the battery(s) stay at operating temperature.

[Starpower]

My '13 12.5 S is more of a wimp then I am and that's saying something! It will not run or charge if the battery pack is below 45F. I roll it out to expose as much of the battery pack to direct sun after 20-30 mins. it will run. Pack measured with an accurate IR thermometer.

[gadgetgirl]

Well, I wouldn't label 20°F as "extreme," especially in Chicago. It does seem to be a design limitation, which at least is in the owner's manual. I'll see if I can get Zero to decode the logs for me. It would be interesting to find a garage around my office where I could plug in a heating mat that I crammed onto the frame somewhere, or parked on. However, it's a lot more straight-forward to just not ride when it's freakin' cold.

Regarding which battery caused the bike to shut down, as I mentioned above, an error was shown on the dash about the 12V battery being ineligible. I don't have reason to suspect the main pack was the reason the computer shut things down, but it was cold too, so maybe. I should be able to see more when I get the logs decoded. I expected the bike to be disabled for 1-15 minutes while the 12V pack warms up. I didn't expect the computer to disable things again at a stoplight.

Has anyone made progress figuring out the encoded SR/F log format to add to https://github.com/zero-motorcycle-community/zero-log-parser? (or elsewhere). I haven't seen a decoded log yet, so I haven't spent time on an updated parser. I plan to noodle on parser code at some point.

[Crissa]

Without Delta T there is no transfer of energy.

...Assuming no other energy source (like kinetic), no gas phase changes (like our atmosphere does), no pressure differential over sheering forces...

And I'm done districting from the conversation.

-Crissa

[ESokoloff]

Well, I wouldn't label 20°F as "extreme," especially in Chicago. It does seem to be a design limitation, which at least is in the owner's manual. ...........

Does Zero claim that the bike will operate @/below these temps?

If so, I miss spoke re limitation & it's a flaw in either design or hardware.

[gadgetgirl]

The manual says the BMS will prevent operation if the main pack is below -22°F. It says it’s not recommended to ride below 23°F, and if it is ridden that cold, to put it on the charger above 32°F as soon as the ride is over. It also mentions that in “extreme” cold, the power and range may be reduced. All those add up to operational, though not optimal/recommended, and all referring to the main pack (I think). It talks about the bike being disabled until the 12V pack heater can warm that pack to 32°F, but apparently the heater doesn’t keep it warm during the ride.

[ESokoloff]

The manual says the BMS will prevent operation if the main pack is below -22°F. It says it’s not recommended to ride below 23°F, and if it is ridden that cold, to put it on the charger above 32°F as soon as the ride is over. It also mentions that in “extreme” cold, the power and range may be reduced. All those add up to operational, though not optimal/recommended, and all referring to the main pack (I think). It talks about the bike being disabled until the 12V pack heater can warm that pack to 32°F, but apparently the heater doesn’t keep it warm during the ride.

If Zero can't do anything for you suggest you install some type of heater for the 12v battery https://www.google.com/search?q=silicone+heater&client=safari&hl=en-us&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjo_5PR3oHnAhWWvp4KHX-_AwAQ_AUoAnoECA4QAg&biw=1024&bih=672

[Crissa]

Yeah, taking Eric's idea further, you can totally get heating pads to stick to the block of batteries or any components to maintain their temp into operating levels while the bike is on.

It'll just eat a little range.

-Crissa