Winter battery cover FLIR One measurements.

Joergen8

Active Member
Sounds a bit over engineered. And I think those hand warmers are also like 5W, so pretty useless when your hand already puts out tens of Watts. For the extra battery, I'd maybe try a hauling it in a backpack, and pack the battery in it so it's close to your back, and insulate it towards the elements with padding.
 

BikeMike

Active Member
When the bike shuts off, muscle power is all you have. And these mid motors like Bosch, with small front chainrings and an internal reduction of etc. 1:2.5 (where the chainring spins 2.5 times per crank revolution) , can feel somewhat sluggish to pedal unassisted.

I can only say from my own experience, but below 40 F is where things start to get hairy, and you can't trust the BMS not shutting the battery off at random. With a winter cover, never a problem, even at 0 F.

The battery has quite a bit of thermal mass, so if you wrap it up tighter than a cat burrito, it should hold its heat for a good while.

Lights only take up a few watts, whereas to generate any resistive heat inside the battery you'll need at least ten times or more power draw, so riding at a high assist level will generate a fair bit of resistive heat, but low assist or just lights won't. For example, in my posts above I tried charging the battery with the winter cover on for a few hours, and my charger is 2A at 36V, so there's 72W going into the battery, and it received nearly no heat gain above the ambient temp.

These brand name bikes are pretty well protected against software tampering, or even pulling out any usable metrics. A voltage drop would only occur when the frigid battery chemistry can't keep up with the load (Amperage), and the BMS shuts it down since for all it "knows" low voltage equals low state of charge. Low voltage could end up frying something anyway, so it's all for the better, and rather than logging when it happens, you can just prevent it from happening by controlling the operating temperature with thermal insulation.
Sounds like I should be fine, if i put a thermal protector on below 40F. I have velosurance, that offers roadside assistance. 25F is my lower limit.

If you asked me, a 15T sprocket only belongs on a rear cassette. I love a 50T chainring because it pedals so smoothly and efficiently. I just cannot get over a 15T chainring . It looks like a fragile toy to me. Then, some mountain bikes have gigantic cassette sprockets to compensate.

I can only shake my head in disbelief. Reduction belongs in the hub, not bottom bracket. that design is just plain wrong to me. Like adding a car part to a beautiful bike.
 

BikeMike

Active Member
Sounds a bit over engineered. And I think those hand warmers are also like 5W, so pretty useless when your hand already puts out tens of Watts. For the extra battery, I'd maybe try a hauling it in a backpack, and pack the battery in it so it's close to your back, and insulate it towards the elements with padding.
Good answer. I have an avalanche transponder. You are supposed to wear it close to your chest.

I could get something like a sling to wear under a jacket.
 

BikeMike

Active Member
Sounds a bit over engineered. And I think those hand warmers are also like 5W, so pretty useless when your hand already puts out tens of Watts. For the extra battery, I'd maybe try a hauling it in a backpack, and pack the battery in it so it's close to your back, and insulate it towards the elements with padding.
I have avalanche certification. They taught us to NEVER use lithium ion batteries in the transponders. Always use alkaline. But, we have no control over battery chemistry.
 

BikeMike

Active Member
When the bike shuts off, muscle power is all you have. And these mid motors like Bosch, with small front chainrings and an internal reduction of etc. 1:2.5 (where the chainring spins 2.5 times per crank revolution) , can feel somewhat sluggish to pedal unassisted.

I can only say from my own experience, but below 40 F is where things start to get hairy, and you can't trust the BMS not shutting the battery off at random. With a winter cover, never a problem, even at 0 F.

The battery has quite a bit of thermal mass, so if you wrap it up tighter than a cat burrito, it should hold its heat for a good while.

Lights only take up a few watts, whereas to generate any resistive heat inside the battery you'll need at least ten times or more power draw, so riding at a high assist level will generate a fair bit of resistive heat, but low assist or just lights won't. For example, in my posts above I tried charging the battery with the winter cover on for a few hours, and my charger is 2A at 36V, so there's 72W going into the battery, and it received nearly no heat gain above the ambient temp.

These brand name bikes are pretty well protected against software tampering, or even pulling out any usable metrics. A voltage drop would only occur when the frigid battery chemistry can't keep up with the load (Amperage), and the BMS shuts it down since for all it "knows" low voltage equals low state of charge. Low voltage could end up frying something anyway, so it's all for the better, and rather than logging when it happens, you can just prevent it from happening by controlling the operating temperature with thermal insulation.
Here is some confirmation about 40F. Bosch actually draws the line at 50F or 10C.

Difficult conditions*
Hilly terrain, approx. 25 km/h (Speed: 30 km/h), headwind, < 10 °C outside temperature, high rolling resistance, unfavorable gear shifting, weight without eBike > 85 kg, additional connected components, e.g. lights.

Ideal conditions*
Flat terrain, approx. 15 km/h, no headwind, approx. 20 °C outside tempera- ture, low rolling resistance, optimal gear shifting, weight without eBike < 70 kg, no additional connected components, e.g. lights.

http://www.moustachebikes.com/uk/images/pages/Bosch-eBike-Battery-Guide-2017-EN.pdf

After all 0C is freezing. Freezing temperatures or lower must wreak havoc with any type of electro-chemical mix.
 

BikeMike

Active Member
Good answer. I have an avalanche transponder. You are supposed to wear it close to your chest.

I could get something like a sling to wear under a jacket.
Am i being stupid?

My original intention was to buy a foul-weather bike. The Operating temperatures for foul weather is primarily 25F to 50F, exactly what Bosch calls "difficult conditions". I intend to use my conventional bikes in 50F and higher temperatures.

Honestly, am I being stupid?
 

BikeMike

Active Member
Sounds a bit over engineered. And I think those hand warmers are also like 5W, so pretty useless when your hand already puts out tens of Watts. For the extra battery, I'd maybe try a hauling it in a backpack, and pack the battery in it so it's close to your back, and insulate it towards the elements with padding.
I think i am being dense about cold weather. Tesla S lost about 33% of the projected range. Dumb, dumb, dumb.

To its credit, the Model S delivered 176 miles from a full charge in cold weather--considerably more than any other EV on the planet. While it was in line with what the car predicted, it proved well short of the rated 240 miles the car promised when I started, let alone the 265 estimated by the EPA or the 300 touted by Tesla. So even for the impressive Model S, it turns out that range anxiety is not completely eliminated. Adapting to EVs needs and limitations is still relevant. But the Tesla has proven to have far less limitations than other EVs

https://www.consumerreports.org/cro/news/2013/02/winter-chills-limit-range-of-the-tesla-model-s-electric-car/index.htm
 

BikeMike

Active Member
This graph suggests to use an ebike in Denver only during the summer months, according to Bosch. Exactly, what i plan NOT to do. Certainly, do not use eBike from December through February, according to Bosch and the graph. The winter months are when the eBike has most value to me. That's when i would use it most heavily. That is what most of the accessories are intended for.

The more I investigate an eBike, the mor marginal the utility becomes. The 300 pound total weight capacity limit imposed by Trek was the first instance. Now temperature range marginalizes the battery to six months. Insurance costs were another blow. Very inconvenient bike shop locations.

The prospect grows dimmer at every decision point.

IMG_0667.PNG
 
Last edited:

Big Tom

Member
Damn, I can be dense at times.

Typical conductivities of liquid electrolyte at:
  • room temperature (20 °C (68 °F)) are in the range of 10 mS/cm,
  • increasing by approximately 30–40% at 40 °C (104 °F)
  • and decreasing slightly at 0 °C (32 °F).[91]

https://en.wikipedia.org/wiki/Lithium-ion_battery#Electrolytes
Put your spare battery in a cooler with a microwavable hot pack. They make "coolers" to transport food that do this, like a pizza delivery guy would use. The ones we use (for food) are the size of a casserole dish
 

BikeMike

Active Member
Put your spare battery in a cooler with a microwavable hot pack. They make "coolers" to transport food that do this, like a pizza delivery guy would use. The ones we use (for food) are the size of a casserole dish
Very imaginative!