battery capacity is going down

[davideos]

The state of charge is still a bit of a guess. I've noticed that the depletion rate is very non-linear. If I look at trip meter and compare to the SOC, I only get about 1.5KWhs for the first 10%, and a similar amount for the subsequent 10% drops in the SOC. After that, the ratio does improve a little. So for my FFE, I see a definite loss in capacity; but that should be expected. Temps here are in the mid 70s to 80 deg and the tires are new...same tires as before.

 

[michael]

Yes, I've seen the same thing. SOC drops quite fast for the first few miles and then declines more slowly.

Although it's not perfect, I think the approach recommended by one of our board members to run the heater full blast with window open is the best available means to compare battery capacity among us. As I mentioned, I did this recently and got a value in the mid to low 17's

 

[WattsUp]

Although it's not perfect, I think the approach recommended by one of our board members to run the heater full blast with window open is the best available means to compare battery capacity among us.

And, to be clear, what you mean is, after a full charge, turn the car on, reset the trip meter, and -- without driving the car -- run the heater until the battery is depleted.

The idea here is that the trip meter will count the total kWh used to "run" the car from full to empty (heating or driving, makes no difference to the battery or trip meter), therefore revealing the total usable battery capacity of your FFE.

In then follows that, if you run the same test later (under as close to the same circumstances as possible), a comparison of the trip meter results will show (at least at a coarse level) any battery degradation.

 

[hybridbear]

Although it's not perfect, I think the approach recommended by one of our board members to run the heater full blast with window open is the best available means to compare battery capacity among us.

And, to be clear, what you mean is, after a full charge, turn the car on, reset the trip meter, and -- without driving the car -- run the heater until the battery is depleted.

The idea here is that the trip meter will count the total kWh used to "run" the car from full to empty (heating or driving, makes no difference to the battery or trip meter), therefore revealing the total usable battery capacity of your FFE.

In then follows that, if you run the same test later (under as close to the same circumstances as possible), a comparison of the trip meter results will show (at least at a coarse level) any battery degradation.

The only issue with that is what ETE did you start with. Now that FORScan works on Android devices with the FFE I have started logging my ETE at a full charge along with HVB temp & SOC. Over time this will allow me to calculate the battery capacity & any capacity loss. It will also be possible to see the relationship between HVB temp & capacity. There does seem to be a fair bit of variation in starting ETE at a full charge which muddies the trip meter heater results.

I've been tracking this data on our Fusion Energi for a few months using Torque Pro and I'm glad to be able to now get the same data for the Focus Electric.

The state of charge is still a bit of a guess. I've noticed that the depletion rate is very non-linear. If I look at trip meter and compare to the SOC, I only get about 1.5KWhs for the first 10%, and a similar amount for the subsequent 10% drops in the SOC. After that, the ratio does improve a little. So for my FFE, I see a definite loss in capacity; but that should be expected. Temps here are in the mid 70s to 80 deg and the tires are new...same tires as before.

I believe the % displayed on the MFT screen is the "Displayed SOC". This is the same value used to show how full the icon is on the dash. What I've found thus far with the Fusion Energi is that the displayed SOC stays at 100% while the absolute SOC drops up to 5%. The displayed SOC isn't truly linear. It appears that anything above a certain ETE displays 100%, what varies is how far above that value you can charge the car. I'll work on gathering data with FORScan for the Focus Electric and let everyone know.

 

[WattsUp]

The only issue with that is what ETE did you start with.

ETE? "Energy to empty"?

There does seem to be a fair bit of variation in starting ETE at a full charge which muddies the trip meter heater results.

What makes the ETE vary?

In any case, assuming one can reproduce the same test circumstances, including the starting ETE, wouldn't the comparison of two tests be fairly accurate (non-middied)?

 

[WattsUp]

I believe the % displayed on the MFT screen is the "Displayed SOC". This is the same value used to show how full the icon is on the dash. What I've found thus far with the Fusion Energi is that the displayed SOC stays at 100% while the absolute SOC drops up to 5%. The displayed SOC isn't truly linear. It appears that anything above a certain ETE displays 100%, what varies is how far above that value you can charge the car. I'll work on gathering data with FORScan for the Focus Electric and let everyone know.

Interesting. Why do you think it works that way?

Do you think it might be so that, when the car is new, it "over charges" but still just displays 100%. Then, as the battery degrades, and can't really "over-charge" anymore, the car still shows 100%?

In other words, have they built in a bit of a "fudge factor" to account for battery degradation? (At least in terms of the SOC display.)

 

[hybridbear]

The only issue with that is what ETE did you start with.

ETE? "Energy to empty"?

There does seem to be a fair bit of variation in starting ETE at a full charge which muddies the trip meter heater results.

What makes the ETE vary?

In any case, assuming one can reproduce the same test circumstances, including the starting ETE, wouldn't the comparison of two tests be fairly accurate (non-middied)?

Yes, ETE=Energy to Empty. The ETE on a full charge varies based on battery temp and a few other factors. We've also found that Go Times can sometimes partially deplete the HVB by a small amount.

I believe the % displayed on the MFT screen is the "Displayed SOC". This is the same value used to show how full the icon is on the dash. What I've found thus far with the Fusion Energi is that the displayed SOC stays at 100% while the absolute SOC drops up to 5%. The displayed SOC isn't truly linear. It appears that anything above a certain ETE displays 100%, what varies is how far above that value you can charge the car. I'll work on gathering data with FORScan for the Focus Electric and let everyone know.

Interesting. Why do you think it works that way?

Do you think it might be so that, when the car is new, it "over charges" but still just displays 100%. Then, as the battery degrades, and can't really "over-charge" anymore, the car still shows 100%?

In other words, have they built in a bit of a "fudge factor" to account for battery degradation? (At least in terms of the SOC display.)

I'm not sure. I've been able to figure this out based on the Fusion Energi. On it you might show and ETE of around 7.050 to 7.200 with a full charge. The ETE can be as low as 6.700 and the MFT screen (Displayed SOC) still shows 100%. In the Focus you can see the variation in a full charge in how long it takes before you get regen after a full charge.

 

[jjsv1]

I just ran the heater test on my '13 with 18k miles on the clock (just got it preowned with only 16500) and I got 15.9kWh. Should I assume this is normal or bring it up with the dealer?

 

[fbitz777]

seems low ...I would ask dealer if he can reset the battery and force a re- balance (will take many hours)

at 16k I am still getting 18-19k on my 2016FFE

 

[triangles]

I just ran the heater test on my '13 with 18k miles on the clock (just got it preowned with only 16500) and I got 15.9kWh. Should I assume this is normal or bring it up with the dealer?

Where you are at determines if it's normal or not. Available capacity is temperature dependent. If it were 80F out it would seem low to me. For somewhere where it gets cold in January I'd say it's about right. Even if your battery is below average in capacity the dealer won't do anything about it. There is no capacity guarantee.

 

[awefulspeller]

I just ran the heater test on my '13 with 18k miles on the clock (just got it preowned with only 16500) and I got 15.9kWh. Should I assume this is normal or bring it up with the dealer?

What was the ambient temperature? It's been cold lately and i've noticed about 15kWh when it is below 50 degrees. 2013 with almost 30,000 miles

 

[jjsv1]

Florida. I would say it was about 75 today.

 

[triangles]

That seems low. What are you using to charge it? I'm not sure when or what it takes for the cells to balance themselves but it sounds like your pack may need balancing or possibly have some weak cells. It wouldn't surprise me if you're using an L1 charger and it needs a L2 charger to balance the cells or something like that. Hopefully someone more knowledgeable than I that knows when/how the car balances the cells chimes in.

 

[jjsv1]

I was using a level 1 for about 2 weeks. Currently I'm using the Home Chargepoint L2 Charger. The app shows FFE taking 7ish kw when plugged in.

 

[WattsUp]

The app shows FFE taking 7ish kw when plugged in.

I was under the impression that the FFE has only a 6 kW charger on-board.

What year is your FFE?

 

[jmueller065]

I was under the impression that the FFE has only a 6 kW charger on-board.

What year is your FFE?

Remember FFE's charger is 6.6 kW and the ChargePoint app is going to report the power going into the car, not the power consumed by the battery (that old 90% figure again). Thus 6.6/.90 = 7.3

 

[WattsUp]

I was under the impression that the FFE has only a 6 kW charger on-board.

What year is your FFE?

Remember FFE's charger is 6.6 kW and the ChargePoint app is going to report the power going into the car, not the power consumed by the battery (that old 90% figure again). Thus 6.6/.90 = 7.3

I don't think that's right.

A 6.6 kW charger is rated as such because it can apply 6.6 kW to the battery. Otherwise, known as the "rate" of the charger.

The expected 90% efficiency of the battery itself for accepting a charge would imply that that FFE battery should be able to store about 5.9 kWh for every 6.6 kWh applied to it by the on-board charger.

This jibes with the (nominal) 19.5 kWh capacity for the FFE and typical 3+ hours required to fully charge it (under the BEST circumstances):

19.5 kW / 5.9 kWh = 3.3 hours

Your suggestion that the full 6.6 kWh is stored every hour does not really jibe:

19.5 kW / 6.6 kWh = 2.9 hours

That's just a little too fast to fully charge the FFE.

(Personally, I have never been able to fully charge from the vicinity of 0% SOC in anywhere less than about 3 and a half hours.)

 

[WattsUp]

But, yes, you did remind me of the overall 80% charging efficiency -- which does make sense of the OP's observed "7ish" figure.

Explanation:

Roughly 10% is lost in the basic process of charging the battery (i.e., to store 0.9 kWh in the battery, you must apply 1 kWh to it). (This is the 90% ratio jmueller is referring to.)

Another rough 10% is lost converting power and running the on-board charger in order to apply that 1 kWh (i.e., applying 1 kWh to the battery requires that 1.1 kWh be consumed "from the wall").

Thus, the combined "wall-to-battery" losses can be expected to total about 20%, and overall charging efficiency to be 80%. (Btw, for anyone reading this for this first time, these type of losses are true for all EVs and most kinds of battery charging in general.)

And now the OP's observed "7ish" figure makes sense...

Assuming his FFE's on-board charger was maxing out and applying 6.6 kW to the battery, it very well could have been consuming power at a rate of 110% of that from the wall (the ChargePoint station):

6.6 kW * 110% = 7.26 kW

7.26 kW is indeed "7ish".