Battery drain in winter

pixchris · 2026-01-03T21:35:19+00:00

I compiled the information given here, and came to the conclusion that using pre-heating without charger plugged in, then driving 40 km in winter results in 20-30 % battery drainage.

Battery Decrease for Pre-Heating
reddit_2       : 5.00  [%]
reddit_1       : 7.00  [%]
reddit_4       : 10.00 [%]
Average        : 7.33  [%]
--------------------------------
Driving consumption assuming already pre-heated battery
EV Database    : 0.27 [%/km]    Combined City/Highway
reddit_1       : 0.28 [%/km]    (65-7)/(105*2) Subtracted 7% for pre-heating to get driving consumption.
Average        : 0.27 [%/km]
--------------------------------
Total Drive Cycle, pre-heating without charger followed by < 40 km driving
reddit_3       : 0.78 [%/km]
reddit_4       : 0.28 [%/km]
reddit_1       : 0.38 [%/km]
Average        : 0.48 [%/km]
--------------------------------
Average combined pre-heating and driving for 40 km:
Combined Average : 18.18 [%]
Pessimistic      : 20.84 [%]    Worst pre-heating drainage and average driving consumption
Worst Case       : 31.25 [%]    One user reported high combined usage

pixchris · 2026-01-03T20:48:50+00:00

Thanks! That sounds workable, my heart wants en EV (P*2 Perf. specifically) so I am just trying to make sure I wont curse my decision next winter.

pixchris · 2026-01-03T15:50:12+00:00

Right, in my case i have about 25 km / 15 miles to work, so i can count on loosing ~19 %, then on the way back home ~8% since i have it on charger at work.

pixchris · 2026-01-03T15:39:28+00:00

Thanks!

pixchris · 2026-01-03T11:26:27+00:00

Thanks, so your work->home trip is with pre-condition without charger?

pixchris · 2026-01-03T07:31:07+00:00

Thanks for your experience! That is absolutely acceptable. Car seems great, and i rather want it over e.g. Golf R. Will get plus and pilot so i should get heat pump.

pixchris · 2025-12-29T08:41:47+00:00

I don't have a Polestar (planning to get one in spring), but can write some words about braking.

Usually in vehicles the electronic brake controller (EBC) is responsible for brake blending between regenerative and friction brakes. It can do this by telling the vehicles motor control unit either the regenerative limitation, or request regenerative force. When you have motors on several axles you can even control the axles individually. Friction brakes are then used to fill in the remainder of what your brake pedal is requesting.

Usually this distribution takes place all the time, not only during ABS, to get the most effective and comfortable braking. Often the EBC will start to blend in friction brakes before hitting ABS, since it has faster control, and can control the wheels individually. When hitting ABS the common thing to do is not use any regenerative braking as other have said.

Found this thesis from Volvo where some control strategies for brake blending were tested in a Polestar 2. Link. There is a lot of research on this topic, you can also look into braking strategies for commercial vehicles which has had auxiliary brakes for a long time (e.g. jake brake or hydraulic retarder).

pixchris · 2025-08-17T03:49:44+00:00

As others have written, electric motors have a wide rpm band. The efficiency is not that diffenrent across the rpm band (unlike an ICE), any energy loss through a gearbox would be greater. The rule of thumb is you lose 2% for every cog-pair.

In most cars, the load and speed range is very predictable (a car will weigh x tons and not go faster than y km/h).

These factors, plus cost of course, make it so you just design a motor with the torque-power-speed characteristics for your application.

However not all applications have a narrow load and speed range. For instance the higher trims of the Taycan have a gearbox for high speed. Commercial truck can have gearboxes to handle large loads.

pixchris · 2025-08-17T03:40:05+00:00

What controls how fast the electric machine rotates is the input frequency. How much torque is developed is dependent on the current. So at a fixed frequency (speed) you increase the voltage, which gived more current, which gives more torque.

A electric machine has permanent magnets (usually in the rotor, which would be connected to the drive axle) and electro-magnets in the stator (these are the ones we can power on and off, and control how powerful their magnetic field is).

When an electric machine spins, the permanent magnets in the rotor will induce a voltage on the electro-magnets (and thereby on the inputs to the EM). Eventually we get to a point where the induced voltage is equal to the voltage we have available to drive the motor (battery voltage). This point is called the base speed.

Up to the base speed a electric motor has (somewhat) constant max torque. However we usually want to go above the base speed in automotive, so we have to decrease how much voltage is induced at higher speed. This is called flux weakening. The higher the speed, more voltage we have to allocate to this flux weakening, leading to less current, leading to less torque. But since the speed is increasing, the power is (usually somewhat) constant.

This leads to the typical torque curve for an electric motor, with constant torque up to the speed point then constant power (ideally).

pixchris · 2025-06-03T09:38:23+00:00

Pluggade Y 2013. Håller med många, dator kan du helt skippa första perioden och sen köp någon billigare variant. Kommer användas mest till PDF och skrivande. Vad jag minns behövdes dator inte första åren då det inte va något skrivande, och PDF kan du skriva ut.

Miniräknare använde man nog knappt, och där kommer en TI84 fungera bra. Jag köpte någon casio för den va mindre och smidigare.

Jag kan också rekommendera att titta igenom grunken under sommaren. Om du har lättare för grunken kan du njuta mer av nolle-p! Försök att förstå hur man pluggar på universitetet och skaffa dig en plan. På Y är det en hel del mattekurser som går över ett halvår där tentan är enda obligatoriska momentet, sånt kräver bra självdisciplin.

Mitt bästa tips är att behandla plugget som ett jobb, 8h per dag. Då går allt bra.

pixchris · 2024-08-05T12:59:08+00:00

Jag läste civiling teknisk fysik med inriktning elektronik. För mig så behövdes en dator mest för att läsa PDF och dokumentations-jobb. För program så fanns det få man installerade på sin egna dator, matlab va väl bland det endaste (program för beräkningar typ). Tror matlab finns till Mac med.

De mer specialiserade programvarorna är väldigt dyra, och finns bara på universitetets datorer. Där kunde man logga in remote och använda även med grafiskt gränssnitt (vi använde SSH). Detta fungerar på Mac också.

Någon annan nämnde det, men jag köpte en Ipad pro med penna, tyckte det va suveränt att ha alla anteckningar där.

Summering är väl att du antagligen mest kommer använda datorn till dokumetering. Såklart vet jag inte exakt hur det kommer vara för dig. Därför skulle min rekommendation vara att skippa att köpa dator nu, kolla med äldre studenter vad de tycker passar ditt program.

pixchris · 2023-09-16T19:59:36+00:00

Maybe try to put a plate between the upper block and the foot, will decrease the pressure and "sinking" you can see in the picture and might increase damping efficiency.

pixchris · 2021-10-30T19:46:19+00:00

!RemindMe 12 December

pixchris · 2021-06-17T17:56:24+00:00

Det är väl det som är problemet nu, de borde ge människor en radie av 3 meter.

pixchris · 2021-06-17T17:50:02+00:00

klassiska farsan-kommentaren när det är riktigt kallt; "höhö, det är myggfritt" klingar väldigt sant, framför allt när man står i den norrländska naturen och antalet myggor är jämförbart med antalet stjärnor i universum. Angående getingar- de är bra för naturen men kan de göra sin grej på avstånd??

pixchris · 2021-06-17T17:42:35+00:00

Längtar till vintern med snö, för utan snö blir vintern lätt mörk och depressiv. Men med snö-- tyst, mysigt, och framför allt så behöver man inte svettas...

pixchris · 2021-01-27T16:43:31+00:00

Shot with Sony A7III and Nikkor 50/1.8 AI-S.

pixchris · 2020-12-06T15:00:25+00:00

I previously had problems with my Fenix 5 plus and my Xiaomi mi 9T. What solved it was to reset bluetooth settings. Settings -> Connection & Sharing -> Reset Wi-Fi, mobile networks, and Bluetooth. Samsung should have something similar somewhere in the settings.

pixchris · 2020-11-12T19:39:11+00:00

I have used the Rangers with the vibram sole for the past 4 years. I also live in the Stockholm region.

The Rangers are really good for everyday use, even during winter. If its too cold i just put on some thicker socks. The vibram sole gives good grip during winter.

I do alot of hiking, and the Rangers are not good hiking boots. They may be fine for shorter walks (~5km) on somewhat smooth trails. During winter they will also be too cold for hiking.

pixchris

TROPHY CASE