lower temperature > lower batt voltage > less energy?

No, the low voltage limit remains at 2.5V for shutdown, and below 2V permanent damage my occur, no matter what the temperature. But below about 20°C LiFePO4 cells tend to develop strongly increasing internal resistance / impedance, thus leading to a far higher voltage drop when a specific current is drawn. And this reduced power is basically what diminishes your useful range at cold cell temp. Battery heating is imperative for any lithium-based cell chemistry that is to be used at temperatures below 20°C with more than 1C discharge current.

Battery heating is imperative for any lithium-based cell chemistry that is to be used at temperatures below 20°C with more than 1C discharge current.

20C? Do you mean 0C?

While I agree that the cells don't charge well at 0C, mine discharge just fine at freezing and down to -10C (coldest that I can stand riding). However, the top speed goes down noticeably due to a greater voltage sag.

Then again, the two cells that have developed a high charge/discharge resistance and needed replacement are the front-most two, which would get the coldest when riding. The scooter is charged and stored in a garage where the temperature stays at least a few degrees above freezing.

I believe that as the temperature drops, the safe low-voltage limit under a substantial load (0.75C or so) goes down as well. In fact, I think that that the bike control unit in my Current scooter adjusts the low-voltage cutoff trigger downward for temperatures below 5C or so.

However, to answer Hybride's question, it stands to reason that if the voltage sags more for a given discharge current, then the usable energy of the cells will go down, unless you discharge the cells at a very low rate, but unless they are poor-quality cells this effect should minimal as far as reduced range at a balmy 10-15C.

When the weather gets a little cool out here in Southern California (60 degrees Fahrenheit, LOL) my bike seems to perform better than at higher temperatures.
My thinking is the resistance goes down and stays down in the motor and other components due to the cooling effect of the lower temperature.

Best would be battery at 35 to 40°C and cables, controller and motor windings and magnets at -40°C :-)

And yes, PJD, I do mean 20 degrees Celsius. Of course there are LiFePO4 cells on the market with less internal resistance than my orignally 40Ah GBs, so their voltage drop at less than 20°C will be less than in my aging battery. But the older such a battery gets, the more it benefits from warmth, I can feel that every winter morning.

"Best would be battery at 35 to 40°C and cables, controller and motor windings and magnets at -40°C :-)"

"And yes, PJD, I do mean 20 degrees Celsius."

Actually, heat is very detrimental to LiFePO4 (or LiFeMnPO4) cells. They may discharge with less voltage sag at 35to 40C but they won't last very long if consistently at those temperatures.

Maybe it is becasue I rarely ride or roads that require the scooter's top speed, but I find that there is entirely too much fussing over LiFePO4 voltage sag at cold temperatures. My 60AH 72 volt GBS pack does fine in weather colder than I can stand. The only problems I experience at lower temperatures are in charging. What happens is that a particularly high resistance cells will prematurely hit 3.65 volts at the normal 9 amps charging current, triggering the charger to switch to 0.5 amp "balance mode", resulting in hours at in balance mode to reach fully charged.

Today was beautiful, I'll use to scooter to go to work tomorrow, but after that things look marginal. I picked the last of the kale and spinach out of the garden today.

http://forecast.weather.gov/MapClick.php?lat=40.48812&lon=-80.23200&FcstType=text&unit=1&lg=en

40°C in the battery is a very rare occurrence in these latitudes, that might only happen on the hottest 35°C summer days. With your 60Ah pack you have a full 50% higher capacity and thus possibly also 50% lower impedance than my 40Ah pack, and I do not know the current draw of your Current ride, but suspect it will be in a similar range as my Thunder with bursts up to about 140A at times. That is 3.5C for my pack, but only 2.3C for yours. That stresses your cells far less. So the cold does not bother your ride as much as it does mine...