Speak EV - Electric Car Forums banner
1 - 7 of 7 Posts

·
Registered
Nissan Leaf 40, 2018
Joined
·
192 Posts
Discussion Starter · #1 · (Edited)
I did a fairly lengthy (for me) journey home from England one day last week (325 miles) and the weather there was rather warm. I have a 40kWh 2018 Leaf. It was the first time I ever saw my battery temperature gauge go into the red but nothing changed about how the car was driving. There was no restriction in power output or speed. And there was no prominent warning light or message. If I had not been checking the temperature myself, I would never have known that it had gone into the red.

Automotive design Personal luxury car Car Vehicle Electronic device


I had done 252 miles by that point, having done four rapid charges en route, and was heading for home. I had been keeping an eye on the battery temperature during the charges and it never went into the red during charging. My last charge was on the Osprey at Alnwick. The charge was throttled back to 17kW, which I assumed was the car limiting the current to protect the battery. (The Osprey charger could give 50kW.)

Light Vehicle Font Gas Technology


Light Audio equipment Font Gadget Screenshot


I have read a lot about ‘Rapidgate’ on this forum and elsewhere which had led me to believe that there was some kind of cliff edge, where the Leaf’s BMS would severely limit charging power on a third or subsequent rapid charge on the same day. However, in my experience, it just seems to regulate the power smoothly, gradually pulling back on charging power to keep the battery temperature out of the red. There was no ‘step change’ in charging power. And 17kW is not disastrous. It’s about 60mph (at 3.5 mile/kWh). For me, ‘Rapidgate’ does not seem to be too bad a problem while charging. If that is the slowest it gets, on a hot day down south, then I can live with that.

However, I had assumed that driving the car is much less onerous on the battery than rapid charging it. At 70mph I would only be drawing about 20kW, and the air flow under the car would help to cool the battery. So I was surprised to see the battery temperature continue to increase as I was driving. I was on the A1, which is limited to 60mph. With traffic, average speed is less than that.

When I saw that the battery temperature had gone into the red (top photo in this post), I wondered if the car would start to limit the traction current to protect the battery. But, no. I could not detect any constraint on power for accelerating and no speed limitation.

When I got home, I checked Leaf Spy and got these screenshots of the battery temperatures and condition. The timeline is incomplete because I did not have the dongle plugged in throughout the journey.

Rectangle Slope Font Line Parallel


The big increases were at 3.4 hours, when I used a FastNed rapid charger at Barnard Castle. And then at 5.5 hours, when I used the Osprey at Alnwick. (It was in the sun, hence the increase in outside temperature to 29C while stationary.)

Colorfulness Rectangle Font Line Material property


But my point is (a) my surprise that the peak temperature (54C) occurred not while on a rapid charger, but while I was driving. And (b) that the car had no protection in the BMS to limit current while driving to protect the battery, and no warning light or message to alert the driver to the high temperature.

So my questions are:
  • Does that match your experience with Rapidgate while charging and battery temperature while driving?
  • Should I have continued driving or should I have stopped to let the battery cool when I saw the gauge go into the red?
  • Is 54C harmful to a Li-ion battery?
 

·
Registered
Joined
·
62 Posts
It takes a while for the temperature created inside the cells to reach the temperature sensors, hence the delayed shock of temperature increase.
Also driving and regen breaking over cir 20kW does create some heating too (40Kwh model), in all, once temperature starts ramping up, it seams hard to stem it unless cruising at a sedentary 45-55 mph
 

·
Registered
NISSAN LEAF 62Kwh
Joined
·
3,691 Posts
Once the battery temperature indicator goes into the red, then the vehicle will limit the power available and the level of regen the battery can take. This might not be noticeable in normal driving but if you have to call on full power to say quickly overtake a slower vehicle, then that power serge might not be there like you would expect it to be.

The Power Meter has calibrated indices (segments) going clock wise in white indicting power available and in blue anti clockwise indicating available regen. When all the segments are lit (white and blue) then full power and regen are available. If only the first few white segments are lit then full power is not available so it is a go idea to keep an eye on the power meter in conjunction with high battery temperatures.

As an example: When you charge the battery to 100%, the power meter will only have 3 blue segments lit which indicates regen is restricted because the battery is full and cannot take anymore charge (although in practice it does allow some). When the battery is at 90% all the blue segments are lit and full unrestricted regen into the battery is available.

If you need to reduce the battery temperature, then draft a wagon at 58mph for a few miles.

It's 3 things that makes the battery heat up - Rapid Charging - Sustained high drain on the battery such as high speed driving - a low state of battery charge. Minimise these and it's happy days.
 

·
Registered
Joined
·
142 Posts
If you want to travel longer distances in a day.
Fully 100% charge and rest for two hours to cool battery before start.

Don’t rapid charge for more than 20 minutes

Don’t charge above 75%

Rest battery for couple minutes before and after charging

Be gentle on accelerator and brakes.

Only needed for over 400 mile trips.
 

·
Super Moderator
Joined
·
7,714 Posts
I did a fairly lengthy (for me) journey home from England one day last week (325 miles) and the weather there was rather warm. I have a 40kWh 2018 Leaf. It was the first time I ever saw my battery temperature gauge go into the red but nothing changed about how the car was driving. There was no restriction in power output or speed. And there was no prominent warning light or message. If I had not been checking the temperature myself, I would never have known that it had gone into the red.

View attachment 163487

I had done 252 miles by that point, having done four rapid charges en route, and was heading for home. I had been keeping an eye on the battery temperature during the charges and it never went into the red during charging. My last charge was on the Osprey at Alnwick. The charge was throttled back to 17kW, which I assumed was the car limiting the current to protect the battery. (The Osprey charger could give 50kW.)

View attachment 163488

View attachment 163489

I have read a lot about ‘Rapidgate’ on this forum and elsewhere which had led me to believe that there was some kind of cliff edge, where the Leaf’s BMS would severely limit charging power on a third or subsequent rapid charge on the same day. However, in my experience, it just seems to regulate the power smoothly, gradually pulling back on charging power to keep the battery temperature out of the red. There was no ‘step change’ in charging power. And 17kW is not disastrous. It’s about 60mph (at 3.5 mile/kWh). For me, ‘Rapidgate’ does not seem to be too bad a problem while charging. If that is the slowest it gets, on a hot day down south, then I can live with that.

However, I had assumed that driving the car is much less onerous on the battery than rapid charging it. At 70mph I would only be drawing about 20kW, and the air flow under the car would help to cool the battery. So I was surprised to see the battery temperature continue to increase as I was driving. I was on the A1, which is limited to 60mph. With traffic, average speed is less than that.

When I saw that the battery temperature had gone into the red (top photo in this post), I wondered if the car would start to limit the traction current to protect the battery. But, no. I could not detect any constraint on power for accelerating and no speed limitation.

When I got home, I checked Leaf Spy and got these screenshots of the battery temperatures and condition. The timeline is incomplete because I did not have the dongle plugged in throughout the journey.

View attachment 163490

The big increases were at 3.4 hours, when I used a FastNed rapid charger at Barnard Castle. And then at 5.5 hours, when I used the Osprey at Alnwick. (It was in the sun, hence the increase in outside temperature to 29C while stationary.)

View attachment 163499

But my point is (a) my surprise that the peak temperature (54C) occurred not while on a rapid charger, but while I was driving. And (b) that the car had no protection in the BMS to limit current while driving to protect the battery, and no warning light or message to alert the driver to the high temperature.

So my questions are:
  • Does that match your experience with Rapidgate while charging and battery temperature while driving?
  • Should I have continued driving or should I have stopped to let the battery cool when I saw the gauge go into the red?
  • Is 54C harmful to a Li-ion battery?
I think power -is- limited in your first picture, only 13 grey segments are there on the power indicator, not all 14. Regen also looks like it’s limited to 5 of 7 blocks.
 
1 - 7 of 7 Posts
Top