A day in the life of a Phoenician Leaf Battery

There has been a lot of speculation on the cause of the rapid battery degradation experienced in Arizona and other hot states beyond what Nissan appeared to expect. Some have suggested that the hot asphalt may be baking the battery beyond the 120F_24hr/140F_absolute_max that the battery is warrantied for.

To shed some light on the topic I purchased a couple of these and stuck one underneath my Leaf for a week. Specifically, on the driver-side, towards the back. I removed three 10mm bolts in the shield there, pulled the shield gently down, shoved the datalogger up against the battery housing, and replaced the screws. This, I believe, gives a good measure of the temperature the battery is being exposed to.

After a week, I've found that the battery was exposed to a maximum of 5 degrees more than the daily max reported by wunderground. This occurred on Thursday when I left work early to run an errand before businesses closed so I was out during the peak heat and saw the battery temp hit 115F versus the reported max of 110F. On my typical days, the battery temperature maxed out at a temp very near the daily max (since I usually leave work after temperature is starting to drop). I also took a log of the EVcan bus on 6/28 to show the amount of charge in the battery at the various temperatures seen throughout the day (plotted below). I did not see anything unexpected or alarming.

Very cool info! Could have used a different thread title though, I was expecting a day's summary of what it's like to drive/own the Leaf in Phoenix.

Thanks so much, TickTock! Now, if you ever have to let your LEAF sit in the sun (on asphalt) for several hours let us know if you see much difference.

Very interesting data. It is easy to forget how misleading ambient temps are. In the sun it can easily be 20+ degrees F. hotter than in the shade. Very curious to hear more from you about temps after a fast charge or two and leaving the leaf in hot sun... That is if you are brave enough to beat up your battery in the name of science. Not sure I could leave my leaf dying in the sun after all the reports of the battery not responding well to excessive heat. Parking in the garage like you did seems like the best idea.

Interesting blog on AZ temps in the summer:
http://www.city-data.com/forum/phoenix-area/106718-safety-arizona-sun-your-car.html" onclick="window.open(this.href);return false;

"The “valley of the sun” has a nice sound to it in the winter time, however in the summer time it can be a killer. Many new comers to Phoenix metro area forget about just how hot it can get and tend to run errands while they leave their child or pet inside the car. I have some interesting stats that I found today while checking the air conditioner in the SUV."

The outside temperature in the shade was recorded as 109 degrees in mid afternoon.
The temperature recorded in the sun while outside at the same time was 125 degrees.
---->>>>The temperature recorded inside the SUV on top of the dashboard was 183 degrees.<<<----
And the temperature recorded inside the SUV in the shade and on the seat was 135 degrees."

Awesome data. I might suggest covering the temp probe with some amount of insulative material - (even though it appears you've located it where it's covered by the battery cover). This will let the temp probe measure the temp of the battery case and be less influenced by the air temps and give you a more accurate reading of battery temperature.

Still pretty easy to see that your battery is probably over 100*F mark on average, which matches battery temp gauge readings you guys are seeing where it might dip to 6 bars in the morning but quickly hits 7 bars during the day.

Contrast that to the Volt who's batteries don't exceed 90F and will get chilled to 75F when turned on or plugged in (can't remember the exact details and can't find the reference right now!). I did find a quote from Bob Lutz who suggested that temps over 95-100F are sort of a tipping point for their batteries where degradation really starts rising...

TickTock said:

There has been a lot of speculation on the cause of the rapid battery degradation experienced in Arizona and other hot states beyond what Nissan appeared to expect. Some have suggested that the hot asphalt may be baking the battery beyond the 120F_24hr/140F_absolute_max that the battery is warrantied for.

Click to expand...

The Nissan warranty is indeed intact at these temps. But the warranty as we know does not cover gradual degradation not even if its faster that expectations set by Nissan.

Pike Research indicate that keeping the battery between 14-86 degrees is required for long life/good performance. Looks like your battery was above the 86 degree threshold the entire day. One can expect and we have witnessed faster than expected degradation as a result of these higher than optimal battery temps.

I wonder if sticking Peltier coolers to the outside of the battery pack housing and plugging them in overnight would help get the battery into a safer temperature zone. Bit of a kludge, but anything has to be better than nothing.

drees said:

Contrast that to the Volt who's batteries don't exceed 90F and will get chilled to 75F when turned on or plugged in (can't remember the exact details and can't find the reference right now!). I did find a quote from Bob Lutz who suggested that temps over 95-100F are sort of a tipping point for their batteries where degradation really starts rising...

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I think this is the reference you could not find. The Volt's battery is insulated due to the TMS philosophy.
Volt-thermal-management-system-temperature-band
http://gm-volt.com/forum/showthread.php?5243-Volt-thermal-management-system-temperature-band&p=48601#post48601" onclick="window.open(this.href);return false;

I don't subscribe to the idea of air conditioning the garage but I do think I will investigate ventilating the garage better at night since the outside temperature is a full 20 degrees cooler by morning.

Where exactly are you taking the measurements? I can shoot a temp sensor on those areas and compare the to the actual pack temps.

drees said:

Awesome data. I might suggest covering the temp probe with some amount of insulative material - (even though it appears you've located it where it's covered by the battery cover). This will let the temp probe measure the temp of the battery case and be less influenced by the air temps and give you a more accurate reading of battery temperature...

Click to expand...

This is a good point. from pavement you are dealing with penetrating, radiant heat which may actually warm the mass of the car more than the air around it. a probe inside the car would be great too. Someone just told me last night about a fan that is designed to fit in the window of the car like this one: http://www.sportsimportsltd.com/sopoaucofan.html. seems like Pheonix would be a very good place for a solar cooling fan in the window!

Heavily insulating one's garage would help reduce the heat sink effect and help the car cool down at night. and as you suggest, a ventilation fan would be the easiest addition. The warranty suggests that the number of hours of continuous heat is key, maybe getting the car cool enough at night is as important a the peak temp during the day.

GaslessInSeattle said:

Heavily insulating one's garage would help reduce the heat sink effect and help the car cool down at night. and as you suggest, a ventilation fan would be the easiest addition. The warranty suggests that the number of hours of continuous heat is key, maybe getting the car cool enough at night is as important a the peak temp during the day.

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Ambient low at my home at 5:30am today was 82, the garage was 84 at the same time. I keep the doors open at night to let it vent. I don't see how fans would help all that much, insulation probably would. I suppose if you had to keep the garage doors closed for security a fan would be advisable at night.

Outside it's 111 right now with the garage at 93 with doors closed. A fan would be counter productive during the day IMHO. The crawl space of the house is 77 thanks to the ac ducting, just can't get the car in there :-(

GaslessInSeattle said:

drees said:

Awesome data. I might suggest covering the temp probe with some amount of insulative material - (even though it appears you've located it where it's covered by the battery cover). This will let the temp probe measure the temp of the battery case and be less influenced by the air temps and give you a more accurate reading of battery temperature...

Click to expand...

This is a good point. from pavement you are dealing with penetrating, radiant heat which may actually warm the mass of the car more than the air around it. a probe inside the car would be great too. Someone just told me last night about a fan that is designed to fit in the window of the car like this one: http://www.sportsimportsltd.com/sopoaucofan.html. seems like Pheonix would be a very good place for a solar cooling fan in the window!

Heavily insulating one's garage would help reduce the heat sink effect and help the car cool down at night. and as you suggest, a ventilation fan would be the easiest addition. The warranty suggests that the number of hours of continuous heat is key, maybe getting the car cool enough at night is as important a the peak temp during the day.

Click to expand...

Actually I did have it in a ziplock (in case it rained or I had to drive through overflowing irrigation).

Also, my garage is insulated. That was one of the things I made sure of before closing on the home. Just not air conditioned. Insulation is a 2-way street, though - why it stays a constant 100 degrees instead of heating up to 110 or cooling down to 80. Maybe with an active squirrel cage fan that only comes on when the temp out is lower than the temp inside, I can keep it closer to the night-time temp...

That is GREAT data, and great formatting! I've often wondered about the difference between asphalt/concrete (I park on a concrete lot during the day) as we don't have a lot of asphalt around Dallas. Even though my garage stays below 90F and my Leaf drops to 6TB at night (if it hits 7TB during the afternoon), I've wondered if garage fan(s) would help. Based on comments in this thread, I doubt it (and i don't want to introduce any vents into a secure garage).

Perhaps an "entrepreneurial Phoenician" could come up with an evaporative cooling blanket for their electric pony ... a poor man's TMS?

http://ak1.ostkcdn.com/images/products/L12998478.jpg" onclick="window.open(this.href);return false;

Strap it under the battery pack and drive over a sprinkler once a day -- good to go.

Carcus said:

Perhaps an "entrepreneurial Phoenician" could come up with an evaporative cooling blanket for their electric pony ... a poor man's TMS?

http://ak1.ostkcdn.com/images/products/L12998478.jpg" onclick="window.open(this.href);return false;

Strap it under the battery pack and drive over a sprinkler once a day -- good to go.

Click to expand...

[Rummaging, mumbling to self] "I know I have a felt-blanket in this garage somewhere - If it works for canteens . . . "

I think I'll bring my infrared thermometer to work with me on Monday and find out what the temperature is of the pavement in the parking lot where my Leaf is parked all day.

Has anyone determined if the temperature inside the cabin affects the temperature of the battery any? I leave my windows cracked about an inch to keep it from getting so terribly hot in my car during the day. I've never actually taken measurements but I'm willing to bet it makes at least 20 or 30 degrees difference. I would think some of that heat could conduct all the way down into the battery compartment. Not sure how much, though. Since the car is creating its own shade over its parking spot, I would think the pavement directly underneath the car should be cooler than that which is exposed directly to the sun. As for the drive home, I would think since the car is in motion, the wind should keep the heat from the highway from affecting the battery temp as much.

adric22 said:

Has anyone determined if the temperature inside the cabin affects the temperature of the battery any? I leave my windows cracked about an inch to keep it from getting so terribly hot in my car during the day. I've never actually taken measurements but I'm willing to bet it makes at least 20 or 30 degrees difference. I would think some of that heat could conduct all the way down into the battery compartment. Not sure how much, though. Since the car is creating its own shade over its parking spot, I would think the pavement directly underneath the car should be cooler than that which is exposed directly to the sun. As for the drive home, I would think since the car is in motion, the wind should keep the heat from the highway from affecting the battery temp as much.

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I believe the point of the OP was that there was NOT a huge rise in pavement temp, so tracking the ambient temperature (as in whatever is reported by local weather) is sufficient. I experience basically the same weather as you (in North Texas) and find that a (good) sun shade keeps the interior temp reasonable without cracking the windows (which I don't like anyway). Two other observations:
1) parking in shade (like under a tree) seems to make a difference
2) once the battery pack heats up (hits 7TB), no amount of (temporary) wind/air cooling will bring the temp back down until it sits in the garage awhile (this is also why it doesn't heat up until the afternoon).

Carcus said:

Perhaps an "entrepreneurial Phoenician" could come up with an evaporative cooling blanket for their electric pony ... a poor man's TMS?

Click to expand...

Drip a couple of gallons of water on the blanket during the day, perhaps with a small fan to create a breeze if needed.

Herm said:

Carcus said:

Perhaps an "entrepreneurial Phoenician" could come up with an evaporative cooling blanket for their electric pony ... a poor man's TMS?

Click to expand...

Drip a couple of gallons of water on the blanket during the day, perhaps with a small fan to create a breeze if needed.

Click to expand...

Actually, I was wondering if dumping a bit of tap water under the car when I start parking it in the uncovered work parking lot might help.

Leaf cooling blanket(?):

A guess -- 1 gallon a day could ward off the damaging heat in a parking lot. So a gravity feed (might require low pressure electric pump) 5 gallon tank would be good for the work week , with a temp sensor to start gravity flow to the blanket. Prolly feed water to the evaporative blanket from noon till 5 or 6 pm.

/ Is Nissan collecting temp data off of actual owner's cars to work this out? Seems fairly obvious there's a threshold being crossed in Phoenix.