Tips on extending the life of FFE in hot climates

Sorry for the marketing lead in, I don't have any, I'm hoping the bright folks on this forum will chime in.

I'm 2 weeks into my '14 FFE ownership and loving it. I live in Phoenix, nuff said. It's very hot, day and night for 4 months out of the year. The thermal management system (TMS) is one reason I went with the FFE. In reading recent threads here someone mentioned that as the vehicle gets close to a full charge the TMS will come on. If this is the case and I don't need a full charge all the time, should I go a couple days when possible before charging to 100%? Is it necessary to 'turn on' the car for a short time at work while my car bakes in the sun to let the TMS do it's thing?

Looking for any and all tips, thanks!

Congrats on the new Focus! I am still waiting for mine. One of the primary reasons I chose the the FFE was for it's temperature management of the batteries. It gets hot in Austin, but obviously not as hot as Phoenix.

My understanding of Lithium-Ion batteries in general is that temperatures above 86 F can reduce capacity and to minimize lost capacity at elevated temperatures the battery should be kept about 40% charged .(I've also seen recommendations of 30%). This is discussed at length on many Leaf forums.

My understanding is that if the FFE is left plugged in the Thermal Management System will stay active and keep the battery temperature in range.
I've also seen posts where people's FFE notify them by SMS while parked when the batteries are getting too hot and they can remotely turn on the car for 10 minutes to cool down the batteries.
I've also seen strong recommendations to park in the shade on hot days.

I wish the car could be configured to know how much power is needed to get home and automatically turn on the battery cooling system as long as excess battery power is available.

One thing you can do is program your car to charge very late at night. So that it only stays at 100% during the early cool hours in the morning just prior to you leaving for work. Thus your car will not have a 100% charge on it all the time..just those 3 or 4 hours in the morning.
(Mine starts charging at 1am, so worst case empty battery it is still fully charged by 5am--but then I'm in MI so I may see a 100 degree day once per year, but I do see -10F days--quite a few last winter.)

My observations with an OBD scanner show that the TMS doesn't kick in until the temperature is around 98 F. As best I can determine, it does nothing until the temps get there.

That being said, I don't charge til later in the day, and I keep the car shaded whenever possible until then. The battery seems to be well insulated and has a large thermal mass, so it heats up slowly. I've found that leaving the windows down an inch or so makes a big improvement, as does a reflective car cover.

Once you begin charging, the battery tends to heat up fairly quickly, and once the temp reaches 98 the cooling system kicks in.

There isn't one definite recommendation I can make...best is to get an OBD scanner and look at the battery temps in your particular case. The warning to plug in seems to be related, for example, to the external temperature. I've seen it come on when the battery was still in the low 80's, and plugging in would have absolutely no benefit.

My strongest recommendation would be to NOT plug in and charge up when arriving at work in hot weather. Based on what I've seen, this will cause the battery to not only charge up, but also heat up to 98 F at which point the TMS will kick in an limit further increase. Your battery would then spend the rest of the day at 98 degrees and fully charged. This is not the terrible sort of thing that a Leaf would experience, but I think it's better to delay charging and the attendant heating until later in the day. Another good strategy might be to partially charge early on, and top off before going home.

Again, without an OBD scanner, you have no way to know the actual battery temperature...you're just guessing.

michael said:

The warning to plug in seems to be related, for example, to the external temperature. I've seen it come on when the battery was still in the low 80's, and plugging in would have absolutely no benefit.

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PLEASE tell me you're joking! :x

Not certain if now you are are joking or this is a serious question, but....No I'm not joking. That's the way it seems to work. When the OAT reading hits 100, the warning appears. If the battery temp is below approx 98 the cooling doesn't kick in as best I can determine.

Note that the warning doesn't say "your battery is hot". It says "It's hot outside" In a case like this you might be better off unplugged in the shade than plugged in and in the sun.

michael said:

Not certain if now you are are joking or this is a serious question, but....No I'm not joking. That's the way it seems to work. When the OAT reading hits 100, the warning appears. If the battery temp is below approx 98 the cooling doesn't kick in as best I can determine.

Note that the warning doesn't say "your battery is hot". It says "It's hot outside" In a case like this you might be better off unplugged in the shade than plugged in and in the sun.

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I have not owned my FFE through a summer yet so I have not yet gotten a "plug me in!" plea from my car. I just can't imagine why the engineers would base if off of ambient air temp and not the battery temp...

The car who texted wolf.

I cringe when I think of letting my car sit at a low charge level for an extended amount of time. What happens if I have an emergency to attend to at a distant hospital, or something else of grave importance? I always charge to 100%, most times with the FFE being exposed to direct sunlight. I've had my 2013 for over a year and so far so good with no decrease in range. The hit the battery may take in the future is worth the peace of mind of having my FFE fully charged, ready to go for that unexpected emergency that WILL come sooner or later.

I do agree that we here have seen little if any evidence of significant capacity loss. Certainly nothing remotely like the Leaf issue. The problem is that IF one starts seeing it, it's too late to do anything. A few years down the line we will have a much better idea of how much care, if any, is really needed.

However, I take the opposite approach....I'm more worried that 50,000 miles from now I can't make trips that I need to due to capacity reduction. Having the car sit at a low level of charge until I need it worries me much less. But if the charge is really low when I arrive at work, I give it a little squirt, take it to maybe 50% then I can handle routine tasks without issue. At home there's always a second car available.

kmaluo said:

I cringe when I think of letting my car sit at a low charge level for an extended amount of time. What happens if I have an emergency to attend to at a distant hospital, or something else of grave importance? I always charge to 100%, most times with the FFE being exposed to direct sunlight. I've had my 2013 for over a year and so far so good with no decrease in range. The hit the battery may take in the future is worth the peace of mind of having my FFE fully charged, ready to go for that unexpected emergency that WILL come sooner or later.

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Awesome feedback everyone thanks. And kmaluo this is my exact fear with leaving the car at a 40% charge. I have a pregnant wife God forbid I wasn't able to get to her in an emergency because I was purposefully trying to maintain a low charge level.

Also, I get the "It's hot outside plug your car in when possible" every. day. And probably will for the next 3 months.

Another concern I'm having is getting home around 6:30p (ambient temp 105-110), plugging in (I'm using the 110v until I HAVE to get a level 2), car reaches 100% around 3am typically but ambient temp in garage is hovering around 95-100 degrees. So the TMS would be cycling and even though the car is 100%, the TMS is still drawing power from the house (raising elec. bill). Not an ideal situation.

electricAZ said:

In reading recent threads here someone mentioned that as the vehicle gets close to a full charge the TMS will come on.

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That was probably me... here's a recent image capture from chargepoint session (L2) when the ambient temperature was about 81F in the sun.



That hump at the end of the charge cycle, during the "saturation charge stage" is where the TMS noticeably turns on.

At home when I charge at L1 in the driveway, the TMS seems to behave similarly - at about 80F the TMS will come on at the end of the charge cycle (I can hear the pump running), but it doesn't come on anytime before that. When I charge at higher temps (ie 90F-100F) at home, the TMS would activate a few times in the middle of the charge cycle, during the "constant current charge stage".

I have a draft write-up on this; includes links to a batteryuniversity.com article on charging Li-ion batteries that talks about the charging stages:
http://ev-vin.blogspot.com/p/random-images.html

electricAZ said:

If this is the case and I don't need a full charge all the time, should I go a couple days when possible before charging to 100%?

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From what I've read, it's best to keep the state of charge as close to 50% as possible. So rather than not charge for a couple of days, then charge to 100%, I'd charge to maybe 80% every day, especially with a pregnant wife, but only if you have to leave it unplugged. If you're leaving it plugged in, even at L1, I wouldn't be shy about letting it charge to 100% (totally agree with cwstnsko). I suspect doing so probably costs less than 25 cents per night... might come on every few hours... just a guess, based on what I've seen mine do in the driveway parked in the hot sun hooked up to L1.

electricAZ said:

Is it necessary to 'turn on' the car for a short time at work while my car bakes in the sun to let the TMS do it's thing?

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I wouldn't go as far as claiming it's necessary, but in my case it seems to help prevent the car from sending me SOS signals pleading me to plug it in, therefore I recommend it if you have enough charge. From what I've seen, a remote start on a 100F+ day takes about 1kWh of energy. If you decide to try it, please let us know how well it works for you.

I have a couple of blog posts that might help, one is on dealing with hot days (kind of long-winded, sorry):

http://ev-vin.blogspot.com/2014/05/the-heat-is-on.html

Another is a collection of articles on prolonging battery life:

http://ev-vin.blogspot.com/2013/10/prolonging-life.html

what is the ideal way to store the FFE in winter if it will be stored outside?

Last winter i dint drive my 2012 FFE and i was told to charge to 100% and unplug my regular battery.
4 months later i plugged back the battery and my car started and reported my battery at 99%.

The car was stored outside and i live in Montreal so we had day of -20 degrees Celsius.

Did i do the right thing?