An online Ford Focus Electric Forum discussion group

It is currently Mon Mar 25, 2019 10:19 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 10 posts ] 
Author Message
PostPosted: Thu Jan 10, 2019 5:34 pm 
Offline

Joined: Sun Jan 06, 2019 5:37 pm
Posts: 49
I usually drive the FFE about 5-6 miles at a time, come home, and top off. This pattern repeats about 4-5 times each day (I work from home and am constantly running errands). Is the battery happy when its constantly topped off or should I let it get a little lower before recharging?

Thanks!


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 5:09 am 
Offline

Joined: Mon Apr 06, 2015 6:00 am
Posts: 291
121gigawatts wrote:
I usually drive the FFE about 5-6 miles at a time, come home, and top off. This pattern repeats about 4-5 times each day (I work from home and am constantly running errands). Is the battery happy when its constantly topped off or should I let it get a little lower before recharging?

Thanks!


No, I wouldn't do that.

Top off every other day (at the end of the day) or such.

_________________
2015 Magnetic FFE (aka Magneto) - Retired
2017 Kona Blue FFE (aka King Kona) - Current


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 6:50 am 
Offline

Joined: Sun Jan 06, 2019 5:37 pm
Posts: 49
Its a level 2 charger, if that makes any difference. its a ChargePoint, so I can see the voltage dropping while it tops off. Kind of cool that the FFE regulates power like that to keep the battery healthy.

Also, I'm reading that in cold weather its best to keep the car plugged in whenever possible to keep the battery warm. I dont drive much, so if the car pulls energy to keep the battery warm without being plugged in that should be fine. My longest trip is usually 10 miles and I'm home for a couple hours afterwards with plenty of opportunity to charge. My car is garage kept, but its detached and not heated. Its usually around 40 degrees when its 15 degrees outside.

I'm wondering if just using my 120v charger would be a better way to keep my battery charged since its not really ever topping it off, yet keeping it somewhat charged, closer to the 50% happy zone.


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 9:01 am 
Offline

Joined: Tue Aug 16, 2011 11:40 am
Posts: 1033
Location: Toledo, Ohio
Keep using your Level 2 EVSE. Assuming you live somewhere that actually has a winter season, keep it plugged in when it's cold out. A few key facts:
- The FFE had 3 300W coolant heaters (900W total) for the battery.
- The battery thermal management system is not functional when the car is off. It only works when plugged in or car is on.
- Cold in and of itself is not harmful to the battery. Charging a cold battery however is!

That last bit about cold charging is what is so important. Charging a sub-freezing lithium battery causes some of the lithium ions to plate the anode as lithium metal. This non-reversible reaction permanently degrades the battery. Ordinarily a cold battery wouldn't be anything to worry about until you realize that when you hit the brake pedal and regen you are essentially putting a fairly powerful charge spike into the battery. This is why Teslas limit regen when the battery is cold. Unfortunately the FFE does not!

Lithium-ion batteries do not like to be kept at extremely high or low states of charge. There is much debate about what exact SOC range is ideal. It's kind of like asking what motor oil you should use in an ICE. The fact that the FFE limits the SOC to 90% when the dash indicates a 100% full charge mitigates most concerns about keeping the battery at a high state of charge.

The next paragraph contains a great deal of speculation so take it with a grain of salt.

I think Ford tries to heat the battery as much as possible before charging a cold battery. I further imagine that this heating is not perfect to avoid 100% of all negative effects of charging a cold battery. I don't remember where I read it but I believe the charger (in same coolant loop as the battery) can be operated in an inefficient manner as to produce more heat. I believe this is what is happening when you plug in a cold car and you hear a hum that sounds somewhat reminiscent of a distant leaf blower. I didn't notice this until my 3rd winter as my car slumbered in a warm semi-heated garage when not in use.

To ensure the battery is warm as can be when you charge it is the main reason I think always plugging in when you get home is the best course of action in winter for battery longevity. As a secondary benefit the heaters will periodically kick on and keep the battery at a minimally warm temperature. While the battery is kept at a fairly high SOC (not particularly good for the battery), it is less detrimental to the battery than cold charging it IMHO.

In warmer weather 50F+ I usually avoid letting it sit fully charged and plugged in. If I could set a full charge to say 70% or 80% SOC I'd probably just leave it plugged in. It rarely gets above 95F here (TMS kicks in when battery temp exceeds 95F), so having the TMS active while parked isn't a concern for me. I try to run a quick errand once charging is complete and generally wait till the battery is about 40-50% before charging back up as 40-50% would cover most all driving needs for a particular day. Don't get too hung up on charge%, the amount of good/bad for the battery (depending on perspective) is exponential in nature. In other words, ford already has us at a max SOC of 90%, if we kept SOC at 80% instead it would only save a small fraction of the wear and tear on the battery compared to the wear and tear of keeping SOC at 90% instead of 100%. Hopefully that makes sense. I'm not sure of a better way to explain it. If possible just avoid running the battery very low and avoid letting it sit very low for extended periods of time. Same goes for the high end of the charge state. Doing those two simple things will keep the battery almost as happy as if you obsessively kept the battery charge within a fixed range with out all the hassle.

_________________
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 10:41 am 
Offline

Joined: Sun Jan 06, 2019 5:37 pm
Posts: 49
Thanks Triangles! If I decided to keep the FFE unplugged in my ~40 degree garage during the day (between errands) couldn't I precondition the car before heading out to avoid charging a cold battery the first time I use regen braking? Wouldn't that be best of both worlds? I could easily leave it plugged in overnight to keep the battery warm during its coldest points and have a full tank every morning. If I wanted to be extra conservative, I could plug in every other night to keep the SOC closer to the 50% mark, and as long as I precondition it would keep the battery warm correct?

I knew cold charging was bad, but I never thought about regen braking. This makes me want to precondition the car every time I park outside during Iowa winters where our average temps are around 20 degrees with long stretches into single and negative digits.

If I didn't want to constantly worry about it, I agree that just keeping it plugged in seems like it'd be fine. Ford kept the top and bottom 10% open right, so 90% seems like it'd be fine, however most EV junkies talk about the 80/20 rule.


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 12:34 pm 
Offline

Joined: Tue Aug 16, 2011 11:40 am
Posts: 1033
Location: Toledo, Ohio
The battery has a great deal of thermal mass so it's not going to heat up or cool off quickly. One of these days I will be curious enough to see what my battery temp is after a remote start, when I get to work, and after sitting all day at work in a typical 20ish F northern Ohio winter day. I have measured the current going into the battery on regen. I don't remember the exact numbers, my very fuzzy memory makes me want to say it was about 50kW (160A x 325V) going into the battery under max regen. I could be way off here. I don't know at what temperature cold charging becomes a bad thing but everything I've read seems to indicate it's somewhere below freezing and gets exponentially worse the lower temp you try to charge at. So if your garage is a balmy 40F and you run multiple short errands during the day, I wouldn't bother plugging in until the end of the day unless you'll need additional range. There really wouldn't be any reason to precondition either. As far as preconditioning heating hte battery, I would think 900W from the battery heaters alone would take some time to appreciably raise battery temperature. However Ford doesn't offer much info on how the 3 coolant loops interact, so without doing some testing it's hard to say how much preconditioning heats up the battery. Who knows, maybe heat from the cabin heater and waste heat from the charger are used to also heat up the battery... I think you've peaked my curiosity enough I'm gonna hook up my laptop and do some temperature readings this weekend.

I could be wrong but I thought it was only 5% on the bottom end. The 80/20 rule sounds about right to me. I try to do 80/30 when it's warm out. A little higher on the low end to give me a few more reserve miles. I do 70/40 with my model 3 because the battery is so freaking huge. The thing that sucks about the model 3 is the vampire drain as the battery TMS never shuts off. Anyway back to the FFE. If you want to dive deep into the battery specifics Idaho National Labs did testing on a 2013 FFE: https://avt.inl.gov/vehicle-button/2013-ford-focus

_________________
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 12:45 pm 
Offline

Joined: Sun Jan 06, 2019 5:37 pm
Posts: 49
Triangles, you're my kind of car enthusiast. Love the depth of knowledge and curiosity.

Here's another scenario: What if you set your car to value charge, but leave it plugged in all day? Wouldn't this allow you to heat the battery from the EVSE but keep the battery at a happier state until overnight? Minimal difference really, but it would at least let the battery level drop to 60% before I charged it.


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 2:08 pm 
Offline

Joined: Tue Aug 16, 2011 11:40 am
Posts: 1033
Location: Toledo, Ohio
My FFE cannot value charge :cry: as my TCU is garbage. :lol: Yeah that would keep your battery warm. Before my TCU died I used value charging in a manner similar to that. Fair warning when it's cold it will come on and charge regardless of value time setting for about 10-15 minutes. Then stay off until the set charge time. I have no idea why it does this. I suppose its to heat the battery?

_________________
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)


Top
 Profile  
 
PostPosted: Fri Jan 11, 2019 3:18 pm 
Offline

Joined: Sun Jan 06, 2019 5:37 pm
Posts: 49
triangles wrote:
My FFE cannot value charge :cry: as my TCU is garbage. :lol: Yeah that would keep your battery warm. Before my TCU died I used value charging in a manner similar to that. Fair warning when it's cold it will come on and charge regardless of value time setting for about 10-15 minutes. Then stay off until the set charge time. I have no idea why it does this. I suppose its to heat the battery?


Your EVSE can also "value charge" if your car's TCU is busted. My Versacharge had a delay function (2-4-8 hours I believe) and my current Chargepoint has a much more customizable schedule setting. Might be something to look into if you're in the market. What are you currently using? I love how you can monitor KWH usage and cost on your smartphone in real time, as well as schedule charges. You can get them used on Amazon for ~$500.


Top
 Profile  
 
PostPosted: Mon Jan 14, 2019 11:43 am 
Offline

Joined: Tue Aug 16, 2011 11:40 am
Posts: 1033
Location: Toledo, Ohio
I built my own EVSE based on the JuiceBox back when it was still an open source project. It was relatively "cheap" to do back then. IIRC it only cost me about $350. I have already tweaked the code but I'm not much of a serious coder. I supposed If I really wanted to I could write my own delay timer into the code. However the Arduino lacks a RTC so the clock would need to be adjusted quite often. Yeah not worth the hassle. I'm happy with it the way it is. Now if I had TOU electric rates I'd be motivated to do something different.

_________________
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 8 hours


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
cron
© Ford Focus Electric Forum - part of the MyElectricCarForums.com Group