Turbo S and Winter Performance

[Marko]

I have noticed that my Turbo stops functioning properly in subzero temps. Today I had the bike outside during all working day, temperature being at about 8F. When I left for home, only the Eco mode worked, not Turbo or Regen. When back home, the battery did not start charging. The charge at arrival to work was 88%, which had dropped to 83% during the day. This has happened to me before. So, I recommend taking the battery inside during cold days, if being outside means several hours.

 

[Tara D.]

BURRR Yep, I would definitely be taking my battery inside on such cold days!

 

[Marko]

Today it dropped to -1 F so I took the battery in.

 

[Douglas Ruby]

I don't know what the specific battery management software for the Turbo family does, but I know that when I have left my cell phone in the car outside in extremely cold weather, it would refuse to charge or allow the bluetooth to connect until the battery warmed up. The screen would just have a "too cold" message and the phone would be in some sort of self preservation mode. I would actually take the battery out of the phone and warm it up using "warm body parts" or a heater vent to get it to power back on. I would ABSOLUTELY bring the battery inside in any temperature below 32F.

 

[Marko]

I read from Battery University pages that charging a lion battery in temps below freezing is damaging to them. I am guessing that is why Regen is disabled in those temperatures. Not sure though why the Turbo mode would need disabling - possibly too fast discharge rate could be harmful as well.

Another thing I noticed today when I had the battery inside but the bike outside was that the torque sensor gets messed up. I learnt from Specialized tech support that the sensor
works with elastomer stops and they change their behavior when it is cold (wheel keeps spinning after you pedal it). That is like having a throttle on. But now that I had kept the battery in warm, both the Turbo and Regen were available.

EDIT: This is what is said in BU pages: "The performance of all batteries drops drastically at low temperatures; however the elevated internal resistance will cause some warming effect. At –20°C (–4°F) most batteries stop functioning. Although NiCd can go down to –40°C (-40°F), the permissible discharge is only 0.2C (5-hour rate), specialty Li-ion can operate to a temperature of –40°C, but only at a reduced discharge rate; charging at this temperature is out of question."

and "Over-discharge at a low temperature and heavy load is a large contributor to battery failure of cordless power tools."