29 replies to this topic

[plus 3 golfer]

Good to have that confirmation. So as mentioned above, either I am EXTREMELY lucky and still have a 5 year old factory battery that is running great (never had any issues with it going dead. Even left the car sitting for about 5 days unplugged back in May when we were out in California) or someone replaced it prior to me and the counter was never reset. I'll definitely be taking a closer look at the battery this weekend and try to confirm that. Will also give me a chance to take my own look at space around the HVB for cooling per another thread here.

What does your SOC show for the 12V battery?

[rbort]

 I am EXTREMELY lucky and still have a 5 year old factory battery that is running great

 

Why do you say that?  I wouldn't think that is unusual at all, my 12v batteries last close to 10 years usually for me.  The 2013 Cmax I never had any issues with it in 4 years life I had the car.  My truck is 20 years old I've replaced the battery 2 times, and I don't use it that much.  My wife's BMW also only once in the 16 years that we owned it.  Sure capacity of the battery drains down over time so it can last less without the engine running, but if it can still start the engine when you get in then I'm still using it.

 

As far as the hybrid HVB, sure, its losing capacity as well as the Energi battery from the heat.  However there are a couple of differences:

 

a) the hybrid battery is never full, it ranges from 35% to 70% SOC all the time, so batteries are that not full all the time live longer than ones that are full alot of the time.  That's why you DON'T want to plug in the Cmax Energi every chance you get and let it sit at 100% until you use it.  Plan better and only charge it to full shortly before you need to use the full charge.  Otherwise charge it to 50% and use that if its enough. (short trip around town of 15 miles or less).

 

b) its not as evident to see that the hybrid battery has lost 20% capacity.  You can check that by trying to get it as high of a SOC as you can, say 70% and then trying to go as far as you can in EV only and see how much KWH you can get out of it.  Let's say you can use 0.5 kwh, then 20% less and you're going to be 0.4 kwh.  So instead of going 2 miles you will be able to go 1.6 miles.  In the Energi battery full is 5.5 kwh, if you lose 20% its going to be 4.4 kwh.  If you could drive 22 miles on 5.5 kwh (assuming the same performance at 2 miles on 0.5kwh, then its going to be only about 17.6 miles at 4.4.  You're going to notice that alot easier than 0.4 miles loss of range in the hybrid battery.  You would be blind to think that the hybrid battery doesn't lose any range from heat, it does also, its just a much smaller battery to the range difference is much less obvious and even with a loss the car will still do pretty well in MPG because it will still switch off the engine for every stop and every downhill stretch.

 

Some people can drive 6.3 miles per kwh in the summer with the Energi.  Its really a great car as far as efficiency, my wife just got a Mini Countryman SE and with that I can barely manage 5 miles per kwh, in fact about 4.9 is what I got tops.  Due to that I can only go about 25 miles max per charge, even though it has the same size battery (they only rate it for 12 miles I did double that).  However, something about the Energi makes it alot better, and its not weight...maybe its the Michelin tires?

 

-=>Raja.

Edited by rbort, 20 July 2018 - 05:21 AM.

[Tom_NC_1]

Just FYI, 99F on the battery is too hot, if you can not do that it will be better for the HVB.

 

-=>Raja.

 

I don't agree with Raja on this point.  Every summer I am lucky to start the day with the HVB at 80ºf and usually reach 98ºf during the day. This is with only charging once overnight and using a bit less than one full charge per day, even when driving 60 or more miles per day. It is common this time of year for outside air temps to reach mid 90s during the day. I have had no adverse effect on the capacity of the HVB since 2015. 

 

It was the summer of 2015 that I lost about 1kWh of capacity after the HVB hit 113ºf on several occasions before I learned the to prevent overheating the HVB. My goal since then has been to prevent HVB temps from exceeding 102ºf by active monitoring and limiting charging and EV driving as needed.

 

This summer I removed the molding around the HVB exhaust fan and found that with the better airflow it is not hard to keep the HVB from exceeding 98ºf. Every little bit helps. 

 

Tom

[cr08]

What does your SOC show for the 12V battery?

I'll definitely check this later this afternoon when I leave work and report back. Should have the benefit of getting a good reading after sitting for 8 hours (no charging at work unfortunately).

[cr08]

Took some screenshots at a few points on my commute this afternoon. Included appropriate captions in the imgur post:

 

https://imgur.com/a/FCDPdln

[rbort]

Hi Tom:

 

I guess that you decided that 102F is good compared to 113F.  I'm just trying to keep my battery as close to 91F as possible and not go over that by much.  86 is where they tell you is "good" for Li-ion batteries and we all know that hotter is worse than colder.  So while 86 causes some acceptable type of degradation, wouldn't logic state that the hotter you go from there the worse it is?  Certainly 102 is better than 113, but isn't 91 better than 102?  I'm just trying to not get there I'm not happy seeing 95+ on my HVB.  The most I ever reached is 99F and Im trying to stay 8 degrees cooler than that.

 

-=>Raja.

[spirilis]

I can tell you that at 115F, the ECU will limit or eliminate your ability to use EV modes... and even prevent regen in "L" mode (starting the engine to employ engine braking instead).  I hit that yesterday after trying multiple use/charge/use/charge cycles in ~85-90F weather.  HVB temp was 115F when I got home, which is probably my first "hail mary" moment regarding HVB temps.... NOT repeating that one again.

 

Anyone ever try using a "swamp cooler" in the hatch area to cool the air going into the HVB inlet vents?  Wonder if that would be worthwhile.

[rbort]

After all the talk here and 'warnings' about battery temperature, why in the heck did you charge several times as day and use the battery heavily?  Sadly, lithium battery damage is incremental and additive, meaning you lose something from yesterday's event not sure how much exactly but something.  I never hit that limit in my 2013 ever but one winter in FL I spent about 4 days driving about 25 miles in the morning to an event, charging all day and driving back to the hotel 25 miles back 100% EV.  Only 2 charges per day but the temps in FL do not cool much at night even in the winter it was in the 80's to maybe 90 tops during the day and down to only the 70's at night.  Those 4 days in a row did some capacity loss on my battery, not a whole lot but I'd say I lost about 0.1 to 0.2kwh I used to be able to get 5,6kwh out of the battery it was down to 5.5 or 5.4 kwh.  Not much but I did notice it as I'm a pretty particular kind of guy.

 

-=>Raja.

[Tom_NC_1]

Hi Tom:

 

I guess that you decided that 102F is good compared to 113F.  I'm just trying to keep my battery as close to 91F as possible and not go over that by much.  86 is where they tell you is "good" for Li-ion batteries and we all know that hotter is worse than colder.  So while 86 causes some acceptable type of degradation, wouldn't logic state that the hotter you go from there the worse it is?  Certainly 102 is better than 113, but isn't 91 better than 102?  I'm just trying to not get there I'm not happy seeing 95+ on my HVB.  The most I ever reached is 99F and Im trying to stay 8 degrees cooler than that.

 

-=>Raja.

I agree that keeping the HVB as cool as possible is the best practice. Keeping the temp below 102ºf has not caused any additional loss of battery capacity. Even if I were to drive hybrid only and never charge in the summer the HVB temp would easily exceed your 91ºf target. My goal of 102ºf or less is about the best I can achieve in NC. Now with the moldings removed to enable better fan exhaust from the HVB I have been able to keep the HVB below 100ºf most of the time. 

 

I can tell you that at 115F, the ECU will limit or eliminate your ability to use EV modes... and even prevent regen in "L" mode (starting the engine to employ engine braking instead).  I hit that yesterday after trying multiple use/charge/use/charge cycles in ~85-90F weather.  HVB temp was 115F when I got home, which is probably my first "hail mary" moment regarding HVB temps.... NOT repeating that one again.

 

Anyone ever try using a "swamp cooler" in the hatch area to cool the air going into the HVB inlet vents?  Wonder if that would be worthwhile.

From my experience when the HVB reaches 113ºf the available power through EV starts to drop off and soon forces hybrid driving only. Once the HVB gets above 90ºf I do not charge the HVB. At around 100ºf I only drive as hybrid. These actions among others help control the HVB temp to prevent overheating.

 

 

Tom

[spirilis]

Basically no hard data to confirm my battery temp etc... the loss of EV scared me a bit and when I got home I plugged in my panlong OBD-II dongle (usually keep it in the Focus Electric as the C-Max is my wife's car). Now I have a better perspective on that. Really makes the EV mode less useful in the summer.