TexasLeaf
Posts: 70
Joined: Wed Mar 21, 2018 5:37 am
Delivery Date: 21 Mar 2018
Leaf Number: 303111

Drive at night to control battery temperature

Tue Jul 17, 2018 10:59 am

I have read and heard of many people commenting about charging in the shade to control battery temperature and reduce slow charging issues on the 2018 Leaf. I thought to myself, charging in the shade doesn't make any sense because the battery pack is underneath the car and can't get directly heated up by the sun. Then I realized that what people were talking about was charging while your car was sitting right on top of pavement that had been heated by the sun.

The pavement heated by the sun can be 20 degrees F or more hotter than the air temperature. So the air coming right off the pavement to cool the battery pack while charging a Leaf in the shade is a lot cooler than air coming off a non-shade charging area. Good advice, but how do you make use of this advice when there are so few fast charging stations in shady spots?

Simple, travel at night when it's shady everywhere. It's typically 25 degrees F at night cooler than in the heat of the day so, not only is there no heat coming off the pavement at the charging spots and on the highway, the surrounding air temperature is lower at night. The air cooling the battery pack could be 50 degrees or more cooler at night than in the heat of the day.

So to take advantages of nighttime battery pack cooling on very long trips with multiple fast charging stops you should plan your trip so that you do most of your charging late at night after the pavement cools off and in the early morning before the sun has a chance to heat things up. Other temperature controlling techniques in conjunction with nighttime driving, such as driving for range not speed, should further reduce battery pack heating and slow charging issues. I have not had much opportunity to test the nighttime driving to control battery temperature theory but the theory appears sound.

If have any experience travelling long distances with multiple fast charges at night please share your experience related to how nighttime charging speeds compare to daytime charging speeds.
Last edited by TexasLeaf on Tue Jul 17, 2018 7:17 pm, edited 1 time in total.

LeftieBiker
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Re: Drive by night to control battery temperature

Tue Jul 17, 2018 1:47 pm

I'm finding that using a cooled garage is very effective, even when you drive in the daytime, because the pack is cool to start with. That wouldn't apply as much to multiple fast charges on hot days, though.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

WetEV
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Re: Drive at night to control battery temperature

Wed Jul 18, 2018 5:17 am

TexasLeaf wrote:If have any experience travelling long distances with multiple fast charges at night please share your experience related to how nighttime charging speeds compare to daytime charging speeds.


Do clouds count? I've taken a long trip in both the USA and Canada with a 2014 Leaf in winter. That locally means clouds and temperatures near 40F/5C. Liquid cooling from the sky. A wet EV, as usual. I planned the trip to be mostly 100 km/h, or 55 MPH or 60 MPH.

Battery temperature at the start of every charge session was 5 bars or less. 27C or 81F.

Is 20C over ambient about what you see with the 2018?
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

EnigmaEV
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Leaf Number: 301349
Location: Saskatchewan, Canada

Re: Drive at night to control battery temperature

Wed Jul 18, 2018 4:20 pm

WetEV wrote:Is 20C over ambient about what you see with the 2018?


When driving at 100 kph (60 mph) my 2018 pack seems to spend most of it's time around 30C (86F). This holds true for ambient temperatures from 10C (50F) to nearly 30C (86F). At or above 30C (86F) I'm seeing around 35C (95F) in the pack. Below 10C (50F) ambient I usually see about 20C (68F) pack temperature. I don't have access to L3 charging so these are all starting with a relatively cool pack about 2-3C above ambient.
2018 Leaf SL, 12,633 km, 94.81% SOH, 117.88 Hx, 109.449 AHr

jonathanfields4ever
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Location: Kyoto

Re: Drive at night to control battery temperature

Thu Jul 19, 2018 3:08 am

I’ve been meaning to ask about this. Do people just use Leaf Spy to see their battery temperature? The temperature gauge is awful. Does anyone know what it means? I’ve rarely seen it go above half, but we’ve been having a freak heatwave recently and it’s been one notch above the middle almost every day. Any idea what that means?

LeftieBiker
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Re: Drive at night to control battery temperature

Thu Jul 19, 2018 5:28 am

jonathanfields4ever wrote:I’ve been meaning to ask about this. Do people just use Leaf Spy to see their battery temperature? The temperature gauge is awful. Does anyone know what it means? I’ve rarely seen it go above half, but we’ve been having a freak heatwave recently and it’s been one notch above the middle almost every day. Any idea what that means?


Supposedly it's the same number of bars, but with no more borders to let us count them. So I read it in approximate % increments like 40%, 50%, 55%, etc. As for how hot is Hot, I've been keeping my car in a cooled garage during the heatwaves, and it stays at roughly 30-40%. The hottest I've seen was one 29 minute QC on a warm night in which it got to about 60%.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

WetEV
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Joined: Fri May 04, 2012 8:25 am
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Re: Drive at night to control battery temperature

Thu Jul 19, 2018 5:32 am

jonathanfields4ever wrote:I’ve been meaning to ask about this. Do people just use Leaf Spy to see their battery temperature? The temperature gauge is awful. Does anyone know what it means? I’ve rarely seen it go above half, but we’ve been having a freak heatwave recently and it’s been one notch above the middle almost every day. Any idea what that means?


Yes, one of the reasons to own Leafspy is battery temperature display.

Suggestion to Nissan (and GM/Ford/Honda/Toyota/...), put in a real temperature readout.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

cwerdna
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Re: Drive at night to control battery temperature

Thu Jul 19, 2018 9:42 am

LeftieBiker wrote:
jonathanfields4ever wrote:I’ve been meaning to ask about this. Do people just use Leaf Spy to see their battery temperature? The temperature gauge is awful. Does anyone know what it means? I’ve rarely seen it go above half, but we’ve been having a freak heatwave recently and it’s been one notch above the middle almost every day. Any idea what that means?


Supposedly it's the same number of bars, but with no more borders to let us count them. So I read it in approximate % increments like 40%, 50%, 55%, etc. As for how hot is Hot, I've been keeping my car in a cooled garage during the heatwaves, and it stays at roughly 30-40%. The hottest I've seen was one 29 minute QC on a warm night in which it got to about 60%.

As an FYI, the old pre-'18 temp gauge was crap. It had huge overlapping ranges: http://www.electricvehiclewiki.com/Batt ... ture_Gauge. I can't speak to the behavior and ranges for the '18. And yes, use Leaf Spy to read the actual pack temp sensor values.

'13 Leaf SV w/premium package (owned)
'13 Leaf SV w/QC + LED & premium packages (lease over, car returned)
'06 Prius

Please don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

TexasLeaf
Posts: 70
Joined: Wed Mar 21, 2018 5:37 am
Delivery Date: 21 Mar 2018
Leaf Number: 303111

Re: Drive at night to control battery temperature

Thu Jul 19, 2018 2:27 pm

Charging speeds start to get limited at about 90 degrees F, which is about seven bars on the battery temperature gauge. Anything above 7 bars and you should expect slower charging speeds. If you’re fast charging starting starting at 7 bars, the gauge will jump up to 9 bars.

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Nubo
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Re: Drive at night to control battery temperature

Thu Jul 19, 2018 5:11 pm

I understand the motivation, but thread titles like this are what makes normies scoff at the idea of electric cars.
I noticed you're still working with polymers.

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