Replace Miles Range Number on Dash with kWhr Remaining

[TonyWilliams]

I think it's a combination of a less than accurate display of SOC, ("about 8-10 percent" is not accurate), and a poor range estimating algorithm that forces the car to shut down "just in case".

I'm not referring to the current dash mounted "gas gauge", but the measure of SOC that we use as a linear measure of 281 data points reported on the CAN, therefore 10% might be a raw data point of 28.

I say "about 8-10%", because all we have for data points are the fact that the car hit Very Low Battery (8.5% of those 281 data points), and then very quickly went to turtle mode.

So, again, I'm not referring to the less than accurate display.

 

[JRP3]

It's quite possible that Nissan doesn't want you to go below 8% SOC to help preserve pack life. An occasional foray into that range probably wouldn't be harmful but if you were allowed to access it repeatedly it would diminish cycle life. Cells that might last 500 cycles fully discharged can often last a few thousand cycles if shallow cycled. A123 has data showing 10,000 cycles and more using only the middle 10% SOC.

 

[TonyWilliams]

It's quite possible that Nissan doesn't want you to go below 8% SOC to help preserve pack life.

If that's the case, Nissan should have blocked out that 8%. Nowhere that I'm aware of does Nissan say "don't operate the car below X level of charge".

We just have to guess.

 

[surfingslovak]

...two instances that I'm aware of, when the battery gets down to about 8-10% remaining SOC (based on how we're measuring %), the car has quickly gone to turtle mode (about 1.4% remaining).

Tony, I looked at the data set in one of the instances, and we were missing pretty much exactly 1kWh. While reading the shop manual the other day, it occurred to me that this could be due to the firmware upgrade. According to the manual, low battery warning should come up with 4kWh remaining (including the silent reserve we can't touch), but we have been seeing something closer to 5kWh fairly consistently. I PMd Jason to confirm if he had the firmware update or not. Judging by the delivery date, his Leaf was likely manufactured before the earthquake.

 

[JRP3]

It's quite possible that Nissan doesn't want you to go below 8% SOC to help preserve pack life.

If that's the case, Nissan should have blocked out that 8%. Nowhere that I'm aware of does Nissan say "don't operate the car below X level of charge".

We just have to guess.

Going into turtle mode at 8% or so actually makes sense, it gives you more range to get somewhere at low speed. One of the early things that puzzled me were the reports of turtle mode only lasting a few hundred feet and then the vehicle would stop. I'd expect a few miles of turtle mode would be better and not give up much useful pack capacity since range should substantially increase at low speeds.

 

[planet4ever]

8% in turtle mode might give you something like fifteen miles, which sounds great until you try it. I tried turtle once. The issue isn't speed, it's power. You have no acceleration. Even a tiny hill can defeat you. Put bluntly, driving in turtle mode is unsafe. You are a hazard to other vehicles and unable to take evasive actions yourself. I'll take an extra six to eight miles of drivable reserve, thank you, and I'm glad that's what Nissan gave us.

Ray

 

[JRP3]

From what is being claimed in this thread it's going into turtle mode with 8% still left in the tank. As for safety I'll take creeping along on the side of the road for a few miles over being stuck not moving and having to walk.