Lucid Navigation vs Google Maps

[BS8899]

It’s unlikely that your batteries are at optimal temps. When you are on a road trip, your battery is warmer than normal, but unless it’s blazing hot out, your battery is almost certainly not at optimal temps for charging.

I am convinced the main issue for people who don’t get good speeds charging is they simply do not precondition enough.

Here is a recent charging session I was very happy with:
View attachment 29144

This was on a balanced 350, and I was pulling 177kW immediately, since the other Mercedes was also pulling 175ish.

21% to 80% in 27 min on a glorified 150kW charger.

But here the thing, I preconditioned for about 40 minutes beforehand, and check out the battery temp graph:
View attachment 29145
It took about 40 minutes for my batteries to get from “driving temp” of about 80ish F to “charging temp” of about 100F.

So yes, you should precondition. It can only improve your charge.


No. They do not.

I appreciate the tutorial in battery temperature vs charging speed. But that wasn't what I was talking about.

Let's get grounded in some fundamentals:

> charging batteries is a thermodynamic process. As such, it is temperature dependent. "Typically", higher temperatures is favorable to accelerating the thermodynamic process, hence faster charging.
> erosion/degradation is also a thermodynamic process. As such, detrimental effects on charging batteries is also accelerated with higher temperature, correct?
> unless you are ONLY focus on the battery charging speed and don't worry about degradation, there is a delicate balance.
> from what I've read, the optimal temperature for Li-ion batteries are somewhere around 85-90 degrees F. Please correct my misconceptions.

Since half of my long distance driving originates from Phoenix going to Marin County via LA, most of the time, my car/battery temperature is already at the optimal temperature even before I started! Furthermore, as I drove, the batteries gets even warmer. Mos of the time, I AM at the optimal temperature for charging the battery. True?!

Did I "instrumented" my car to know I am at the optimal temperature when I charge? Hell no! But I can hear the (battery) cooling fans kick in soon after I start charging. I KNOW they are "preconditioned" even though I didn't activate preconditioning for 30m before I get to the charging station.

Now, if you living in areas that are mostly in sub-zero temperatures for a good part of the year (as I was in my younger years), the equation is quite different. In those circumstances, perhaps preconditioning has tangible benefits.

My point is, use your head and understand the circumstances and don't just blindly precondition your batteries before charging thinking you will get blazing charging speeds. For my usage model, I've found little differences!

Also, I question the "myth" of preconditioning for 30min when I am doing "daily city charging". Yes, my initial charging speed might be sub-optimal. But does it make sense to waste energy and money (several kWh and $$) to get a slightly faster charging speed just to get the thrill of it?! How does that make sense? I know "time is money". But trust me, your time is not worth as much as you think it does!

 

[borski]

I appreciate the tutorial in battery temperature vs charging speed. But that wasn't what I was talking about.

Let's get grounded in some fundamentals:

> charging batteries is a thermodynamic process. As such, it is temperature dependent. "Typically", higher temperatures is favorable to accelerating the thermodynamic process, hence faster charging.
> erosion/degradation is also a thermodynamic process. As such, detrimental effects on charging batteries is also accelerated with higher temperature, correct?
> unless you are ONLY focus on the battery charging speed and don't worry about degradation, there is a delicate balance.
> from what I've read, the optimal temperature for Li-ion batteries are somewhere around 85-90 degrees F. Please correct my misconceptions.

Since half of my long distance driving originates from Phoenix going to Marin County via LA, most of the time, my car/battery temperature is already at the optimal temperature even before I started! Furthermore, as I drove, the batteries gets even warmer. Mos of the time, I AM at the optimal temperature for charging the battery. True?!

Did I "instrumented" my car to know I am at the optimal temperature when I charge? Hell no! But I can hear the (battery) cooling fans kick in soon after I start charging. I KNOW they are "preconditioned" even though I didn't activate preconditioning for 30m before I get to the charging station.

Now, if you living in areas that are mostly in sub-zero temperatures for a good part of the year (as I was in my younger years), the equation is quite different. In those circumstances, perhaps preconditioning has tangible benefits.

My point is, use your head and understand the circumstances and don't just blindly precondition your batteries before charging thinking you will get blazing charging speeds. For my usage model, I've found little differences!

Also, I question the "myth" of preconditioning for 30min when I am doing "daily city charging". Yes, my initial charging speed might be sub-optimal. But does it make sense to waste energy and money (several kWh and $$) to get a slightly faster charging speed just to get the thrill of it?! How does that make sense? I know "time is money". But trust me, your time is not worth as much as you think it does!

I have tested this empirically, with data. I have tested not preconditioning, preconditioning for 10 min, 15 min, 20 min, 30 min, 40 min and 50 min.

Preconditioning for about 40 min makes a huge difference in charge speed. Past that it doesn’t do much. Fewer than 15-20 min and you may as well not have preconditioned at all.

The “wasted energy” you lose to charging is very minimal, *especially* because your batteries were already *close* to optimal temp but not quite there.

The battery is warrantied and as far as we have seen batteries do not degrade fast enough to worry about in EVs, even if you are exclusively DCFC. Lucid’s rate has not seemed to change significantly regardless of DCFC or not.

DCFC charging (and thus high temps), theoretically and based on physics, should cause faster degradation. It would appear, possibly because manufacturers BMS systems are so good, that isn’t the case as much as theory would tell us it should be. That happens sometimes.

In fact, Emad recently said in a video that they have some evidence (that they are still researching) that DCFC may actually slow *down* degradation if done as a mix with standard charging.

But okay, don’t precondition. I will.

But if you don’t, please don’t also come back to complain later about charge speeds.

You are more than welcome to run your own tests, track the temperature of your batteries, and come back with data disproving mine. I would be completely fine with that, and even encourage it, as then we’d have something to really dig into, and I love learning new things.