[SKPacHy]

Battery logs show maximum available power levels.

Discharge/Charge Power Available:
   HV Battery Charge Power 2sec: 97257 W
   HV Battery Charge Power 10sec: 95040 W
   HV Battery Charge Power 30sec: 83961 W
   HV Battery Discharge Power 2sec: 97374 W
   HV Battery Discharge Power 10sec: 95073 W
   HV Battery Discharge Power 30sec: 91794 W

I avoid driving 75MPH in electric mode. Discharging the entire capacity in 10 min can't be good for the battery health.

Im not so sure. Cruising on the highway takes less power than starting off from a dead stop. The only real problem with a faster discharge is the internal resistance of the cells producing heat. But the Pacifica has a capable thermal management system to control that. In most conditions I bet that’s not even really needed.

 

[SKPacHy]

Just remember that wind resistance increases exponentially. Wind resistance at 75 mph is 4x as much as it is at 37 mph.

So? The issue is total sustained power output, and if that's bad on the battery. Call me crazy but I have a feeling that an automotive high voltage battery was probably engineered with freeway speed travel in mind.

 

[SKPacHy]

I don't want to dig into numbers, generally Li-Ion batteries are not well suited for intensive fast discharge operation. LiFePo4 chemistry is better at this task, you'll find it in the starting batteries, high torque power tools, drones, etc... Pachy uses large pouch cells cooled from the bottom. The top parts of the cells will get hot under fast discharge. The range at 75MPH is nowhere near 32 miles, which means the battery will discharge in 15-20 minutes. Its not going to kill it instantly, but will certainly contribute to its degradation.

Ya my point is always that everything contributes to degradation. Everything. Once a battery is created it’s just a slow march toward its inevitable death. The question is do these use cases, like freeway speed driving, really cause more degradation that anyone is likely to notice. We have no data, but I’m going to suggest it’s probably no. If driving at freeway speeds in EV mode causes 0.00005% more degradation than driving at city speeds, then you’re right that it’s worse, but you’ll never notice over the life of the vehicle. So I think these discussions just aren’t useful when we have no useful data. And if that was really the case why wouldn’t Chrysler have set the switchover speed to Hybrid mode to something like 55mph? If they were worried about battery longevity over that 10 year warranty you’d think that would be prudent. But they left it up at 80+mph. So just drive your van and don’t worry about it!

 

[SKPacHy]

I wasn’t commenting on that. I was simply saying that at some speed (probably lower than most people would expect) the power required to simply keep the car at a constant velocity will likely exceed the amount of power to take off from a dead stop.

As someone who often watches the power flow data, I can tell you that power output at freeway speeds is often in the 20-35kW range. Where starting off from a stop, depending on driving style and whatnot, will often go well over 50kW. Sure it’s a quick excursion up there, but acceleration always takes way more power then cruising, even when the exponential effects of induced drag are taken into account.

 

[SKPacHy]

Is the “switchover speed” fixed? Is it the same whether climbing a hill, descending, or on flat ground?

Well as far as I know there are generally 2 thresholds. One is speed based and one is power output based. Chrysler says EV mode has a maximum speed of 75mph or 121kph. Above that the ICE will start and provide more power. For the power output threshold the ICE generally gets triggered when you get somewhere over 70kW of power output. I usually drive with the EV/Hybrid power circle things in the centre of the cluster. And when you push the pedal down far enough that the EV ring gets filled, and push just a little more the ICE gets triggered, and my my experience that's usually around 75kw-ish.

 

[SKPacHy]

If you have to

That can't be true for 75MPH. When the entire 12kwh is used in 15-20 minutes, the sustained power has to be 36-48kw.

Possible. I don't usually drive at that speed. I'm normally around 110kph. It will also vary with outside air temperature, wind, tire composition and pressure. But my memory is telling me I rarely see that close to 50kw output when cruising. Generally below 40kw. Maybe I'll go test that again today.

But my main point still stands.We spend a lot of time saying what's good or bad or whatever for these batteries when we really don't know. And don't really have any good information to offer. Lots of people do lots of things, convinced that they are changing the world (or at least greatly extending the life of their battery), but the vast majority of it is bunk, and could even be doing the opposite! Like people that force close all the apps on their iPhone thinking they are doing good, when in reality they are hurting their battery life. I say drive the van and leave the engineering to the engineers. Sure they aren't perfect and everyone makes mistakes, but they know a lot more about these things than someone who read 1 article on Battery University and is now an Internet Battery Expert.

 

[SKPacHy]

Of course in reality even if you like to force close all your apps on your iPhone, the extra drain it puts on your battery to reload the apps when you want to use them is likely minuscule.

Thanks for making my point. They think they are helping, even minuscule, but they are actually hurting, even if minuscule. Just like almost every battery discussion online.

 

[SKPacHy]

I don't think anything particularly bad will happen if you drive fast occasionally. I was in these circumstances when I spent a night in a hotel next to I-95, where I had to drive in the morning. But imagining other extreme- commuting at 75MPH and charging at work, the degradation will accumulate.

Says who? Can you prove it? Or do you just feel like that’s true?

And just saying degradation will accumulate is kind of a nothing statement. Degradation accumulates with any usage of a battery. I’m still waiting for any proof that driving at a normal speed for a vehicle will cause exceptional battery degradation that anyone would actually notice.

 

[SKPacHy]

If you have to

That can't be true for 75MPH. When the entire 12kwh is used in 15-20 minutes, the sustained power has to be 36-48kw.

So I went out and did a highway test with my Pacifica to check out the power output. I was driving at 117kph/73mph and the outside air temperature was -12C/10F and I was driving on winter tires. On a flat straight stretch the Pacifica was using 38-41kW to maintain 117kph. But that number includes the 5kW of Climate power that was being used at the time. So the power output for moving the vehicle down the road and for the DC-DC converter was 33-36kW. Which isn't bad considering the conditions. It would be quite a bit less in the summer.