[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.

 

[PacDave]

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.

Well we really do know. Pretty much anything whether it be mechanical or whether it be electrochemical or whatever will wear out and it will wear out faster the more we push it toward its limits. The thing we don’t know, for example, is how much faster the battery will wear out by driving the car at the highest speed permitted by the designers. It is probably not a huge amount but if someone wants to drive 60 mph on the highway instead of 75 mph, then go for it. You will probably increase the longevity of your battery by doing so just as you will probably increase the longevity by driving 45 mph instead of 60 mph. It’s just that the difference in most cases is probably not enough to worry about for most people. The manufacturer of the car designed it to go 75 mph because it will. And they offer a 10 year warranty on the HV battery so they must be pretty confident that the amount of extra abuse the battery receives at 75 mph will not be enough to matter much even if you do it for ten years.

 

[stop-eject]

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.

ShieldSquare Captcha Skip to the "current derating' part. Notice that the optimum rate of discharge is 1C, which for us is 14-19kw, depending on SOC.
Lithium ion battery degradation: what you need to know - Physical Chemistry Chemical Physics (RSC Publishing) DOI:10.1039/D1CP00359C is more about the battery chemistry but mentions that high currents and temperatures contribute to degradation. PacHy cells are large and are cooled only from one side. They are capable of absorbing the heat generated by high currents during acceleration, sustained high currents will saturate them and cause local overheating.

 

[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.

 

[stop-eject]

Thanks for doing the test. It is in line with my best estimates. It is quite impressive that PacHy can still have about 25 miles of range at 75MPH in a cold weather and on winter tires.