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Getting a good range out of your EV driving


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21 replies to this topic

#1 OFFLINE   rbort

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Posted 05 April 2015 - 07:45 PM

Per request, I'm posting some tips and tricks on how to get a better range out of your Cmax in cold weather as well as during the warmer climates.  This is strictly for EV driving no ICE involved.

 

1.  It goes without saying, as much as you may cringe, electric heat kills the battery range.  This is the #1 factor of range reduction.  The best way around this is to not use any heat.  If you decide to go this route, then:

 

a) dress for it, in layers upper and lower section of your body, no different than walking outside for extended distances to walk from the train to work for example.  Don't forget the gloves, maybe even a scarf and a hat.

 

b) Windows tend to fog up in cold weather without the climate control running, to counter this effect you can either apply some rain-x anti fog to the windows and/or crack both front windows to circulate some air in the cabin.  Cracked windows don't need to be much, just 1/4 inch or so on each front side is sufficient.

 

c) heated seats are a good option and do not take much power at all, in fact feel free to use them when necessary, but, like anything else, once your seat warms up if you think you can do without for the rest of the trip then turn them back to 1 or 2 setting or off if the weather permits, the sun is out, etc.  Remember its a matter of range, so if you're sure you're going to make it, don't be as frugal.

 

d) if you have the moonroof, keep it open in the winter to let daylight in, as any sunlight will improve the cabin temperature to more comfortable levels.

 

Know that driving without heat comes with practice, in other words you're not going to go out and drive cold turkey in the dead of winter at 20F.  Its best if you work up to it, meaning you drive without heat all fall and into winter, as you will get used to a colder car over time and before you know it driving in 30 degree weather is not even noticeable.  The hardest days would be the single digit ones in the dark, but if you triple layer it knowing you're going to be out that night, it will certainly help.

 

2.  Now that we got by the heat part, how can you increase the range even further.  You next thing is to drive in the daytime if possible, for at least 1 leg of the trip.  In other words if you're going out to dinner, try to leave the house before it gets dark so you can get to the restaurant without having to use the headlights.  Headlights rob anywhere between 10 to 20 mpge from your battery performance.  High beams take on the order of double the power, and fog lights add about 1/2 draw over the headlights.  This is approximate.  Remember this and use your lights when you need to, but skip the fog lights if not necessary and don't ride around with high beams for extended periods of time, which brings up the next tip.

 

3.  Slow down.  Since you're not using high beams, you can't see as far but if you're going slow enough you won't need them.  Ideally stick to speeds of around 30 to 40 mph.  Remember that the car is always "burning battery" when powered up, so you want to get there but your don't want to go too fast either as it will drain the battery faster and yield less miles due to drag.  Under 20 mph is probably too slow and counter productive, over 40 the wind drag is starting to dig into your range.  If you need to take a section of the highway, do so but remember you can't go as far at higher speeds.  However, a good speed in EV mode for the highway would be somewhere between 45 to 55 mph.  Depends on traffic, your battery % and distance to home is how fast you can go.  If its late at night and you need every mile you can get in EV, go 45mph in the right lane (minimum speed).  If you have to keep up with traffic, shoot for 50 to 55 tops.  Or, take the country road.  Remember always that the shortest way to your destination is probably the best way since you will be going slower (secondary roads) and its less miles so you can make it on EV power.  Don't worry about traffic, if you have to go 35 instead of 45 on a secondary road because of traffic, great, then you're going further and not feeling like you're holding anybody up.

 

4. Regen all you can.  This means you should be shooting for 100% brake scores all the time.  I've attached a picture of my return trip from Worcester back home tonight, over 25 miles and even at 33 degrees outside and running at night, I had 7% main battery left.  How can you do this?  Don't follow anyone too close, look ahead and anticipate/react early.  If the light in a distance turns yellow, do not step on the accelerator any more, let the car coast up to the light.  If the distance to the light is too far, try to see the other crossing light to detect when it turns yellow.  Add a little power to continue slowing down but stretching it, you're trying to either get there with some speed left if the light turns back to green, or get there with no speed and minimum brake needed if you have to stop (still red).  Any speed you preserve helps with your range (not having to stop all the way).  If the light is not that far and just turned yellow, brake immediately and brake lightly all the way to the light.  Milk it so that you use up all the distance to the stop line or the car in front of you.  If possible switch lanes to the side where you can brake further (less cars in that lane in front of you) to gain more regen and better your chance at a 100% brake score.  You have to adjust the brake pedal pressure very gingerly and know from experience given your speed, the incline, and the distance to target (stop area) to know how much brake pressure to apply or release.  Sometimes you might need to let up on the brake slightly so that you will still be regenning all the way to the stop, other times you have to increase pressure slightly to be able to stop.  Your mission is to get 100% brake score, if you scraped the pads, you make a mistake, learn from it.

 

5.  Use cruise control.  Even on secondary roads, almost everywhere except where heavily congested, not only for the highways.  It helps take the load off you of having to feather the gas to keep the car going.  For long distance and given time (not in a rush), I select a speed of about 38mph.  This gives a good balance between getting there and extending your range.  Learn to turn off CC with the button (not the brake) and back on as needed.  However, when you turn it on, do not do so at a slow speed and let it pickup rather aggressively to your target speed, I prefer to accelerate the car myself to within 3mph of the target speed and then turn CC on.

 

6.  Speaking of accelerating, always use the Empower screen (in auto mode) so you can see the bars.  Use no more than 2 bars to get up to speed, but if there is time or no traffic behind you, then use 1 to 1.5 bars depending on the incline.  If you're at a light and its slightly downhill in front of you, use 1 bar.  If its level, go with 1.5 bars.  If its uphill, like an on-ramp to a highway, 2 bars tops, NO matter what don't go over 2 bars.  Only CC is allowed to go over 2 bars in my opinion and it might hit about 2 1/4 bars tops to go up a hill.  The longer you take to get to your desired speed, the more efficient you will be.  If you're faced with a hill, don't be afraid to allow the car to slow down as you climb it.  Sometimes 2 bars you might lose some speed, other times you might do it on purpose and only power up at 1.5 bars to lose some speed (if no-one is behind you for example or you need to turn off at the top).  You can always regain the speed back on the downhill part, but slowly as well.  Don't try to accelerate up the hill back to your speed, wait until the road levels off and keep the same power (1.5 bars for example) in until the car picks back up on its own.

 

7.  Maintain your speed because of drag.  What does this mean?  If you are in CC going 38mph and you are the top of a hill and starting to do down it, what do you do?

 

a) you let it be and have the car run away to 50mph on its own and then slow back down to 38

b) you engage hill decent mode and let the car accelerate to about 41mph and hold its speed

c) you engage L and don't allow the car to get much past 39mph and shift back to D as the hill shallows up.

 

Choice B or C will get you the furthest on the same amount of electrons, because drag at the higher speed of 50 will dig into your final distance that you can travel on the entire battery.  Why B or C?  Well B usually does pretty good in holding the speed unless the hill is quite steep, the C would be best as its max regen and tends to hold the car closer to the desired speed.  B is variable, but I felt that its not as tight as L in holding the speed to a set point.  The difference between B and C is minimal, so to keep it simple use B instead of A for better results.  C is not required if the hill is shallower, and if real shallow D alone in CC would be OK.  You will have to learn to judge what you need when.

 

8.  Accelerating from a stop goes without saying that you should pull out gingerly.  In this car its best not to try to pull out into oncoming traffic, you know, they type where you know you can beat the car coming down the road.  Any hard acceleration from the start is easy to come about when you are trying to pull out quicker than granny slow and also will dock your acceleration coach.  Speaking of the coaches, watch those as part of your screens that you view.  If you're doing ok they should be all full blue 100%.  If any of them are down, work on that issue and learn to fix it.  Trust the coach bars, if they are happy, your will go further in EV mode.

 

9.  An extra bit of regen can be had by shifting to L from D during a full stop at about 6mph.  This is because regen stops in D around 5 mph, and stops in L around 2.5 mph.  By shifting to L you gain just a little bit more regen from 5 to 2.5 mph.  This is also minimal and may add a 1/2 mile range for your entire battery pack, so I skip this unless I am going somewhere far which I know I can barely make it on a 100% charge, then I'll do this as well with every stop to help.  I found that around 6mph shift to L gives the least amount of jolt, its almost seemless.

 

10.  Don't be afraid to use L when necessary.  This is especially true if you crest a hill and are faced with a steep downhill to a stop sign at the bottom.  Immediately shift to L for max regen and pad the brake lightly at first to initiate regen around the battery (circles going around).  At this point judge the distance to the stop sign and your speed/incline and increase brake pressure if necessary ever so slightly to milk it all the way down to the stop sign.  This is the hardest challenge to get 100% brake score, too much braking and you dig into the friction pads and waste regen energy to the battery.  Its not always possible to get 100% brake scores, but always aim for it.  You can also use L while you're still learning to use the brake pedal (without friction pads) to slow down and take a left or right turn on a side street.  Shifting to L gives you almost max regen and you just take the corner in L and shift back to D and keep moving.  You'll need to learn when to shift to L, at what moment, so that when you arrive at the turn you're at the perfect speed you want to be at to commence the turn.  Remember that L has no brake lights, so if someone is close behind you its imperative that you at least pad the brake just enough to see the regen circles around the battery indicating that your brake lights are on.

 

So what is a good range anyways?  In the winter months when its bitter cold average temp of around 20, I was getting 22 miles estimated range -- that was the lowest I saw this year and we had one of the coldest and snowiest winters in Boston.   In the summertime when its warm and ideal say 65 to 75F, then your expected range should be closer to 30.  If you drive down the highway at 50mph, then the range should drop to around 27.

 

And what about preconditioning the car?  Well for starters as far as the winter goes, I've totally abandoned the idea of warming up the car, only because its just wasted energy when I drive off the windows are cracked anyways and its not going to last long anyways in there.  I'll only do it if there is ice or fog on the windows to thaw them out.  However, in the summertime AC is not nearly as bad on range as electric heat, as a comparison, heat can pull anywhere from 5000+w on startup to around 2500 to 3000w to maintain, whereas AC can pull as much as 2500-3000w on startup but only about 625w to maintain.  Due to this the best coarse of action in the summertime when its hot is to precondition the car with the AC until the drop can be seen in the climate meter (down to 625w), then unplug the car and take off with the AC on for the rest of your trip.  In the evenings when its not as hot, you could skip the AC and open the windows instead or just use the AC if you know you will make it on EV power anyways.

 

It goes without saying, always bring your stock charge cord with you on distant trips where you could use it to recharge your car for the trip back home if there isn't any convenient public charger available.  Don't forget an extension cable so you can lock the charger inside the car, unfortunately its not always safe to leave it outside unattended.

 

-=>Raja.


Edited by rbort, 19 April 2015 - 06:33 PM.








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#2 OFFLINE   drdiesel1

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Posted 06 April 2015 - 02:29 AM

Get a 240V charger station :smile2:  That's the best tip :hysterical:


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#3 OFFLINE   Tom_NC_1

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Posted 06 April 2015 - 03:16 AM

Get a 240V charger station :smile2:  That's the best tip :hysterical:

 

I agree. I got my level 2 charger early on and use it daily. This allows me to recover the HVB quickly for additional trips during the day.

 

Here is one additional tip. Using the Downhill Assist button on the gear shift lever is an excellent method to both control the speed on downhill slopes to recover energy as efficiently as possible. 


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#4 OFFLINE   rbort

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Posted 06 April 2015 - 02:17 PM

240v charger is nice but it doesn't improve you driving...  Good for people who need to go in and out several times a day.

 

-=>Raja.


Edited by rbort, 06 April 2015 - 02:17 PM.


#5 OFFLINE   GaryG

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Posted 06 April 2015 - 05:07 PM

Get a 240V charger station :smile2:  That's the best tip :hysterical:

 

Had to give you another "Like" on this post. Just to add to your suggestion, I Balance the Cells with Supercharging and use P&G with N coasting on slower surface streets as much as possible.

 

Tom, also gave you a "Like" for both your X-Gauge tire pressure codes, and I want to help test Cell Balancing if you post the code.

 

Gary


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#6 OFFLINE   drdiesel1

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Posted 06 April 2015 - 05:21 PM

Had to give you another "Like" on this post. Just to add to your suggestion, I Balance the Cells with Supercharging and use P&G with N coasting on slower surface streets as much as possible.

 

Tom, also gave you a "Like" for both your X-Gauge tire pressure codes, and I want to help test Cell Balancing if you post the code.

 

Gary

Had to give you a like for sharing SuperCharging with us :victory:



#7 OFFLINE   Kermit

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Posted 19 April 2015 - 08:34 AM

Thanks for sharing all of these helpful hints. I have learned so much on this forum about driving this car better. I just recently started using the hill descent mode and that has been helping. And I'm using cruise control a lot more often now (pretty much anytime there are not many stop lights/signs on the road I'm traveling), which makes a significant difference in range for me. I have not tried shifting to L while driving, so maybe I'll give that a try.

 

Unfortunately, the midwest isn't quite as progressive as the coasts, so we don't have nearly as many public charging stations. The only place I've charged other than home was in my employer's parking garage, using a standard outlet. On the third day, they told me I was not allowed to do that. So I've been working from home ever since! (I guess no miles can be better than EV miles!) 

 

It's nice to have all of these hints in one place. Maybe someday I'll add one or two of my own!



#8 OFFLINE   rbort

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Posted 19 April 2015 - 07:37 PM

I'm glad it can help you and others Kermit.  I was just reading it again tonight, it sounded good reading it several days later so I think I wrote it well.  Found a typo fixed that.  Cruise control is a really good feature, I use it as well most of the time as it relieves me of having to feather the gas, it keeps my speed constant for a more efficient drive (better than slowing down and speeding up all the time) and it gets me there faster as in general I find myself slowing down without intention when I'm not on it.  Remember if you want to speed up with CC, it takes several seconds for it to take effect, so nudge it once and be patient, the speed will come up within the next 30 seconds or so (not right away).

 

I'm thinking I should add the figures for power usage here of the accessories, its a good thing to know as you are trying to maximize your range:

 

 

Accessories off - 292 watts

Headlights on - 500 watts
Headlights/fog lights on - 688 watts
Radio on - 275 watts
Fan on high - 659 watts
Fan on low - 331 watts
Fan on low/driver seat warmer on high - 443 watts
 
So the energy consumption is:
 
Headlights - 208 watts.
Headlights plus fog lights - 396 watts

Headights High beams = 325 watts

Radio uses negligible power.  Note the amplifier is always on.
Fan on high - 384 watts.
Fan on low - 56 watts.
Fan on low/driver seat warmer on high - 151 watts

Wipers = 150 watts

 

A second measurement yielded slightly different results, so please note the figures are not 100% accurate but should give you some idea better than no idea.

 

 

headlights on:  555 watts

parking lights on: 458 watts
lights off:  328 watts
 
So headlights are 227 watts and parking lights are 130 watts."
 

 

Having this info gives you a sense of how you're affecting your range by using the accessories.

 

-=>Raja.


Edited by rbort, 19 April 2015 - 07:39 PM.


#9 OFFLINE   P=E/t

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Posted 20 April 2015 - 03:47 AM

Excellent points, Raja, all of them are valid as proven by reproducible experimentation and I tend to abide by them. Luckily I go to work early, before rush hour(s) and don't face too many drivers behind me who live by the floor-it-jam-it-to-a-stop school of driving. Here in SE PA we do have ridiculously brief yellow lights however, and these are brake score killers par excellence.

 

Still ... What appears to have the most significant effect on range by far is ambient temperature.

 

I can drive the same route now as I did back in the frigid depths of winter and arrive at work (9.0 miles) with 70% HVB remaining on my best days. 2 bar acceleration and good brake scores. Morning temps are generally in the 50s F now. Back when we faced 20 and even 10 degrees F, I'd barely make 60% HVB remaining, also with 2 bar acceleration and similar brake scores. Once, when I hit 67%, I thought that would be my best score ever, until the temps warmed up and I saw what a difference that made.

 

I've also experimented with 3-bar and 4-bar acceleration and 80-90% brake scores in 50-60 degree F weather, and I still  come out ahead of extremely careful driving on the very same routes back when temps were 10-25 degrees F.

 

This is all with seat heaters only, no cabin heat.

 

Strategically, I'm considering a change next winter. Back in the winter I couldn't make it to work and back on the HVB only; now I arrive home with a surplus of between 4% and 10%. Personally, I really feel scarred by the last two winters. Couldn't even get warm in my own home at many times. Next winter, when we hit stretches of weather under 25 F, I'm seriously considering charging our NRGs (we have 2) up to 80% or so and just driving to work as a hybrid, enjoying the heat brought on by the inefficiency of the ICE and perhaps prolonging my HVB life as well. Having the car parked in the warmish garage in my building, I'll drive home in EV Now and still end up getting way better MPG than the Prius I used to drive, which ran its ICE almost constantly in cold weather.



#10 OFFLINE   rbort

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Posted 20 April 2015 - 06:54 AM

Hi P=e/t,

 

I'm not sure I follow your logic:

 

 

 

charging our NRGs (we have 2) up to 80% or so and just driving to work as a hybrid, 

 

You could still charge it to 100%, use the engine, once the car warms up and the heat demand is less, use the battery to keep things going.  It will dig into the range, but you'll be able to save some fuel by having the battery help the engine with heat and propulsion.

 

Also a question for you, when you drove:

 

 

 

with 3-bar and 4-bar acceleration and 80-90% brake scores in 50-60 degree F weather

 

what's the difference in battery % remaining if you compare that to careful driving, up to 2 bars only and 100% brake scores in the SAME weather.  Just curious how much hit you take for the general aggressive gas/brake driving that everyone wants to do.

 

-=>Raja.



#11 OFFLINE   P=E/t

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Posted 20 April 2015 - 10:10 AM

Hi P=e/t,

 

I'm not sure I follow your logic:

 

 

You could still charge it to 100%, use the engine, once the car warms up and the heat demand is less, use the battery to keep things going.  It will dig into the range, but you'll be able to save some fuel by having the battery help the engine with heat and propulsion.

 

Also a question for you, when you drove:

 

 

what's the difference in battery % remaining if you compare that to careful driving, up to 2 bars only and 100% brake scores in the SAME weather.  Just curious how much hit you take for the general aggressive gas/brake driving that everyone wants to do.

 

-=>Raja.

Raja, as we know, "100%" HVB on the center screen does not mean 100% true, it's somewhere like 90ish. And "0%" means about 20% if I recall correctly. A characteristic of Li-ion batteries is that they can experience more charge/discharge cycles if the top end and bottom end are avoided. For most Li-ion batteries, the ideal place to stop is 4.20V per cell, which is around 85% capacity. The Ford engineers--and all EV engineers--structure the battery management to avoid overcharge and deep discharge, at the expense of a small amount of capacity loss.

 

Some good tables here:

http://batteryuniver...based_batteries

 

I have also read and heartily agree with your other thread here, on HVB care.

 

So my logic goes like this:

 

If I'm going to use the ICE anyway, why even reach 4.2V per cell, or 85%true/100% indicated capacity?

Why not just aim for 80% indicated capacity at the start, which is probably around 70-75% true, and keep the HVB charge/discharge cycle a little narrower, which is known to prolong its service life?

 

This practice will have no effect on range in my scenario. Not while using the ICE. I'd end up in my work building garage with 60-65% HVB if I drove in on EV Now between 20 and 30 degrees F. If it's 10 degrees or so like it was this past winter for prolonged stretches, I'd arrive with barely over 50% HVB if I made the trip in EV Now.

 

Yet here's the thing: with accelerating on the ICE and braking with regen, I could start out with 80% indicated and arrive with 90% indicated! We can drive the surplus chemical potential energy in the gas into electrical potential energy in the battery. At least on my route, with lots of stop-and-go and hills. Either way I have plenty of HVB to make it home later, when I'm leaving a warmish garage and the outside temp is a little less frigid.

 

Again, I'd rather not do this, but the past two winters here were just bloody awful. I find at the moment that there is no temperature that I am willing to call "too hot." Heat just universally feels great. Let it descend on us!

 

And then for your second question: please keep in mind that when I use 3 and 4 bars and get 70% braking scores, it's only for the purposes of scientific experimentation! Like you, I feel awful when I drive that way.  ;}

 

I have images stored at home with the scores but on the same 9 mile route, with ambient temps in the 50s, I get a high of 70% HVB remaining at the end of my commute, and a low of 63% HVB remaining with more aggressive driving. Mostly 3-bar stuff though, just an occasional 4. And it seems to help a lot to remain a careful braking expert--what I mean is, 3 bars of acceleration versus 1-2 will hurt us less than consistent 53% brake scores. Careful braking is supremely important.

 

Still--when it was 10 degrees F out, and I drove like there was an uncooked egg between my foot and the pedals, and I ended up with 53% HVB left on the same trip, not using cabin heat ... that's depressing.


Edited by P=E/t, 20 April 2015 - 10:11 AM.


#12 OFFLINE   rbort

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Posted 20 April 2015 - 10:52 AM

Good post P=E/t, some things to note:

 

Ford charges our batteries to 4.1v per cell at 100% indicated SOC.  The table in your link shows 4.1 as 86%, 4.2 is actually 100%.  I think its a little more than 86% at 4.1, closer to 90% but close enough.

 

When the HVB reaches 0%, you are at 21.5% SOC.  You can still drive on the hybrid battery (same battery just use more energy) until its down to 14.5% SOC, so the range of the hybrid portion of the HVB is another 7%.  At that point you would be down to about 3.2v per cell.  The car's battery pack is made out of 84 cells, so the range is from a low of about 269v to a high of 344v.

 

 

 

Yet here's the thing: with accelerating on the ICE and braking with regen, I could start out with 80% indicated and arrive with 90% indicated!

 

How do you intend to do that?  That can only happen if you play my musical chairs game with the EV mode button, you may have seen the video I made about how to charge the HVB while driving using the ICE.  If you leave it in EV later its not going to let you charge up the battery pack from 80 to 90%, EVEN IF you use the ICE only for acceleration.  The max allowable limit is +2% of the current EV later % setting, so if you went into EV later at 80%, you wouldn't be able to go higher than 82%.  The car would stop charging the battery with the ICE running at 82%, and/or start using dual power ICE and Battery to propel the car forward and use up any excess charge in the battery so it doesn't go over +2%.

 

 

Still--when it was 10 degrees F out, and I drove like there was an uncooked egg between my foot and the pedals, and I ended up with 53% HVB left on the same trip, not using cabin heat ... that's depressing.

 

 

So if you made it half way to work and got there with 53% battery left, sounds like you might just eek out the trip home in the winter with 0-6% HVB left.  If you can do that, then why bother even start the engine unless you want heat I suppose then its a different story.

 

For the record, at 10 degrees out my worst MPGe number was about 128 +/- 2 mpge or there abouts.  When its warm out I could do on average as much as +70 mpge more.  There is definitely a difference and its not only due to the cold battery but due to the fact that the car doesn't roll as easily with the CVT transmission turning with gel instead of liquid oil for lube.

 

-=>Raja.


Edited by rbort, 20 April 2015 - 10:56 AM.


#13 OFFLINE   P=E/t

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Posted 20 April 2015 - 12:40 PM

Raja, I'll quote & reply with copy/paste (in italics) since it's faster when I'm replying to multiple specific points.

 

Ford charges our batteries to 4.1v per cell at 100% indicated SOC. 

When the HVB reaches 0%, you are at 21.5% SOC.

 

-These numbers make me happy indeed! I thought 0% was around 20%; 21.5% is even better, and the 4.1V at the top end is excellent.

 

That can only happen if you play my musical chairs game with the EV mode button, you may have seen the video I made about how to charge the HVB while driving using the ICE.

 

-I love your video! And recall this is not highway driving--it's stop and go with Amp Ramps. Hills. Lots of 'em. So what I've found (mostly when I'm going more than 30 miles total for the day, like to a meeting after work) is that by powering up hills with the ICE and braking on the downside, one often ends up gaining a point or two. As long as we don't lose the percentage gained when the ICE is on, and I'm talking relatively short bursts here, then the next braking adds to it a little more.

 

For the record, at 10 degrees out my worst MPGe number was about 128 +/- 2 mpge or there abouts.  When its warm out I could do on average as much as +70 mpge more. 

 

-Ah, but I have the 2014, with no ability to read MPGe. Unless there's a hack somewhere.

 

And from your post on battery care:

7) When storing the car, whether for 2 days or 7 days or a month, recharge the battery pack back to storage charge level of 60%, +/- 10% is OK.

 

I figure, if I'm going to use the ICE on the way in, and will definitely make it home on EV Now at the end of the day, then it doesn't matter whether I start out with 80% or 100% indicated. In those conditions I'll still arrive at work with 80% SOC or so--way more than I need to get home later. So why not reduce the stress on my HVB by charging it to a lower level?

Here's the table from that Battery University site; I'm sure Ford has done far better than this example, but it gives you the idea about the importance of DoD:

 

Table 2: Cycle life as a function of depth of discharge
A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents also affect cycle life.
100% DoD: 300 – 500
50% DoD: 1,200 – 1,500
25% DoD: 2,000 – 2,500
10% DoD: 3,750 – 4,700
 
Who knows. By the time next October comes to a close, I may be ready to brave subzero temperatures with no cabin heat. But I'm not going to place any bets on it.
 
Oh, and one last thing--while the words "air conditioning" are still anathema to my ears, I did try it in the C-Max, just to see how it works. The power draw is insanely low, once the cabin temp levels off! The Ford engineers must have really crafted a beautiful, efficient A/C system.

Edited by P=E/t, 20 April 2015 - 12:45 PM.


#14 OFFLINE   P=E/t

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Posted 21 April 2015 - 06:51 AM

Yesterday was a good example of the significance of the effect of temperature on EV range.
 
Again, my commute is 9 miles each way, lots of traffic lights, stop signs and short steep hills. Speed almost never over 40 mph.
 
In the morning, temps were in the 40s with heavy rain, which presumably cuts into range in a very speed-dependent manner.
I arrived at work with 65% SOC; for reference my best ever was 70%. Careful driving, no traffic, 2-bar acceleration max and good brake scores.
 
When I left (garage in my building), SOC was 59%. The guys in the garage probably had to shuffle my car around a few times throughout the day. Not sure if they always shut it off either--does it auto-shut off after a time??
 
Temps on the way home were 75F. I got terrible brake scores--stupid people in front of me were incessantly accelerating hard and then jamming on their brakes. Even with long following distances, I kept having to hit 'em hard. It seems that by following at a distance, we can compensate for one burn-n-jam driver. But when you line up a dozen or more of them in a row, it's almost impossible to anticipate their nutty actions and drive smooth. They were often braking in the middle of a block!
 
Anyway, I arrived home with 7% SOC. When it was below 20 degrees out, that would have been impossible with a 59% initial SOC, even coming out of a warm garage and with perfect brake scores. I tried many times. I was either forced into Auto mode and trying to make it on the hybrid portion of the battery, or the ICE came on since I had run that energy out as well.
 
It's fascinating, how much effect ambient temperature has on range and performance.


#15 OFFLINE   rbort

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Posted 21 April 2015 - 07:02 AM

Glad you made it round trip OK.  Sometimes what happens is that the battery cools, and the SOC level can/will drop.  Other times its the opposite, it can get warmer, and the charge level of the SOC can go up.

 

In your example, you got to the office and the battery was warm from driving, but it was cool outside with rain.  The temp of the battery dropped, and in the evening you found 59% instead of 65% SOC,  this is normal, I've had this happen to me many times.  

 

Of course its possible they moved your car around and burned battery, but if they didn't this would be the other explanation.

 

On the other hand, I parked my car the other night with 85% SOC from a short trip from the big-y home (used 10% SOC from 95 to 85).  When I went to use it the next day when it was warmer outside during the day, I powered up and it showed 89%.  So with heat it can go up, with cold it can go down.

 

Where it can bite you (happened to me) was in cold weather I drove to Needham, long trip I got there with 8% charge level, decided to stop at Panera bread for a snack before going to my final destination in Needham to charge back up to 100% and go run some errands.  Leaving the car out in the cold for a 1/2 hour stopped, when I came out I powered up and there was only 2% left in the battery...bummer!  2% was not enough to make it to the charger, I had to fire up the engine to get there, but 8% would have been enough.  Moral of the story is that if you are limited in range and trying to get somewhere during cold weather, keep going while the battery is hot and you'll make it.  Stopping on the way unless brief is not a good idea you won't make your original estimated range.

 

-=>Raja.



#16 OFFLINE   Tom_NC_1

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Posted 22 April 2015 - 04:18 AM

Here are some HVB measurements comparisons under various amounts of power used. There are 84 battery modules in the HVB pack. The 4.07V is as high as the individual modules ever get on a normal full charge. I have not ever tried supercharging techniques. So it looks like the HVB design is very conservative at both the top and bottom end. I have over 20k EV miles in my 2 year old pack and charge to full at every opportunity. With all the regen going on as well the pack is constantly getting much exercise. It will be interesting to see how the pack hold up over time. 

 

|         ScanGauge II             |  MFT   |      

|Average batt                      |        |

|Module Volts       HVB    SOC%    |  SOC % |

|----------        ----   ----     |  ----  |

 4.07V             342V    98%        100%

 3.99V             335V    90%         94%

 3.97V             328V    88%         92%

 3.94V             330V   85.8%        88%

 3.91V             326V    81%         82%  

 3.78V               317V    71%          68%

 3.74V             314V    64%         59%

 3.72V             312V   60.5%        53%

 3.66V             307V   54.3%        45%

 3.67V             308V   51.4%        41% 

 3.66V             307V   50.4%        39%

 3.58V             301V   35.6%        19%

 3.54V             297V   29.2%        10%

 3.52V             295V   23.4%         2%

 3.45V             290V   21.5%         0%

 3.48V             293V   17.2%         0%

 

Note 1: Readings were taken when stopped to minimizes current flow at the time the reading.

Note 2: Compared the average module voltage with the minimum module voltage and there was no difference at the time this test.

Note 3: Test was performed when outside air temp was between 65 and 70 degrees.

Note 4: The lowest ScanGauge SOC is around 14.5% with very complete depletion of the hybrid reserve. I can only get this low occasionally in EV+ under specific conditions. Normally 16% to 17% is as low as it gets.

 

Enjoy,

Tom

 

Edit: Fixed a typo in chart.


Edited by Tom_NC_1, 22 April 2015 - 08:23 AM.


#17 OFFLINE   rbort

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Posted 22 April 2015 - 06:54 AM

Good stuff Tom!  I've seen this data before but good to see it again.  If you were to drive until the empower bar was EV threashold was almost flat, about 1/3 of a bar or so, then you should be at 14.5% SOC and about 270v or so on the packs.

 

Is your entry before the last a typo at 3.3v on the battery pack?  Looks like it might be.

 

Can you check the DC to DC inverter load and see what it takes for accessories if you have time, and fill in a table for us "poor folks" that can't afford a scangage or a level 2 charger?  Here is my table of interest for us:

 

Turn off last on before checking the next item.
 
Power on in P, all accesories off (baseline draw).
In P, turn on radio
In P, turn on driver heated seat, setting 1, setting 2, 3, 4,5, how many watts each.
In P, turn on passenger heated seat, is it the same just doubles the watts?
Shift to R, brake on
In R, brake off backward creep level ground (test in AUTO and in EV Now mode, shouldn't be different but if different list please).
Shift to D, brake on
In D, brake off forward creep level ground (test in AUTO and in EV Now mode, shouldn't be different but if different list please).
Shift to L, brake on
In L, brake off forward creep level ground (any different than D?  Also try in different modes)
In P, turn signal on
In P, Parking lights on
In P, Parking lights with fog lights on
In P, Parking lights with headlights on
In P, Parking lights with fog lights and headlights on
In P, Parking lights with high beams on (fog lights go out I believe or turn them off if not).
In P, Climate on fan, slowest speed (push air directional to feet and face if necessary so climate meter shows no draw).
In P, Climate fan on 2, 3rd ,4th 5th speed etc until you reach max speed.  Power draw each step.
In P, Rear defrost/heated mirrors 
In P, Wipers, on slow continuous speed
In P, Wipers on fast continuous speed
 
If you have time to do it, that will be great Tom and thanks!
 
-=>Raja.

Edited by rbort, 22 April 2015 - 07:23 AM.


#18 OFFLINE   Tom_NC_1

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Posted 22 April 2015 - 08:29 AM

Raja I fixed the typo in the chart. Thanks. I usually don't get to the bottom end of the hybrid battery is because I have a down slope near the trip end on the way home so this charges the battery a bit. I can usually go the final mile without using up any of the battery. 

 

I will take a look at the power usage if I can get both the time and the motivation. 

 

Tom



#19 OFFLINE   Kermit

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Posted 22 April 2015 - 09:26 AM

I was thinking about some of these "best practices" for getting the most out of your battery as I was driving earlier. I think it can easily be summed up in one sentence:

 

"Drive like the grandma you never wanted to get stuck behind before you owned this car."   :wink:



#20 OFFLINE   rbort

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Posted 22 April 2015 - 11:58 AM

You GOT it Kermit, you go from "trying to get there as fast as possible", because nothing else is interesting in the drive of a regular ICE, to "trying to get there as efficient as possible", because all the gadgets in the car keep you happy and occupied and you never worry any more about trying to break your record getting to or from work or on a long trip somewhere.

 

My "rewards" now are going to NY and using only 2.65 gallons of gas for a 175 mile trip.  Before it used to be "hey I did it in 2 hours 20 minutes, what's YOUR record huh?" talking to some friend and trying to show off my speedy gonzales accomplishments.

 

At least one good thing that comes out of driving Maxie, no more tickets, ever.  The cops are bored to tears with me, especially on those late nights where they are hiding in a parking lot in a small town and here I come down the straight away into town doing only 35mph, why isn't this guy speeding??!

 

-=>Raja.


Edited by rbort, 22 April 2015 - 12:01 PM.

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