Display Differences on En Route Battery Warm-Up

[aesculus]

By now many of us have installed the sw that supposedly pre warms the battery while en route to a supercharger to make it more efficient during the early charge cycle.

I am trying to ascertain what physical differences to the cars displays take place when this happens?

I would love to hear some experiences from you and it would be helpful if you could also state which car model (S/X), predicted SoC (%), battery size and estimated outside temperature.

Here are my questions:

• Does the efficiency change during the last 10-20 minutes when it was stable up to that point (Wh/mi)
• Does the estimated arrival SoC change during the last 10-20 minutes when it was stable up to that point (% or dist) but give me an idea of how much it did change
• Do you have any log data that shows when and how much the battery heating in (kW or kWh) was applied?

Thanks for the help.

 

[boaterva]

I think we need a lot of data for this. Do we even know what it’s actually doing? We saw this message for the first time this week (on road trip, don’t usually supercharge) and got it when routing to a supercharger as a destination.

When it’s 85 F outside and you are an hour into a trip, what is it doing? Cooling the battery? Warming it further? If both depending on temperature, there should be a (happy?) medium where the car doesn’t need to do anything, right?

My point is, unless we know the whole algorithm, gonna be hard to compute the ‘cost’ of this for the software. (Or we need a lot of samples at different temperatures?).

What think? If we can create a test routine we could run some trips. Or I wonder if the people that have root access could see what the formula is?

 

[aesculus]

When it’s 85 F outside and you are an hour into a trip, what is it doing? Cooling the battery? Warming it further? If both depending on temperature, there should be a (happy?) medium where the car doesn’t need to do anything, right?

This is a very interesting question. While I don't know the exact settings I assume that 30C is a good operating temperature and one they would love to achieve within reason. That means in some cases you would need to cool or warm the battery to achieve that. If you need to warm it then it may mean that doing nothing might allow enough passive heating (ie not cooling) could be enough.

Now getting ready to SC is a short term situation where they may be willing to operate for a small period of time (20-30 minutes?) at a higher temperature than the ideal running temperature. Again passive heating by not cooling, may be enough to bring the temperature up to 40 C degrees at arrival to the SC. If that is not enough then the active (5kW) heater could kick in enough to try to bring the battery up to 40C at arrival.

So the algorithm as I depicted it is not simple and I am sure it's even more complex due to the fact that the different batteries have different thermal masses, the cooling rate is probably different and driving style probably comes into play.

I was just starting by trying to understand what the car actually might display but if it's anything like I depicted above, that is going to be really hard to decipher.

And don't even get me started on what happens in winter when operational battery heating might be applied too.