Any advice. Lost 30%+ range and Dealer said no dice

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Olagon

Well-known member
Joined
Oct 23, 2014
Messages
169
2014. 60K miles. Garaged in cool valley in Hawaii. Well cared for. But now with 30% range loss I can't make trips to the west side of Oahu anymore. Dealer said no warranty for range reductions but wants to charge me $500 to balance my pack. How did guys here get battery swaps?
 
Battery has to fail for a warranty replacement. I want to say it's been about a year now that the warranty replacement gets you a refurbished battery not a new one. The warranty is clear that there is no degradation guarantee.
 
$500 to balance a pack? What are they going to do, take them out of the car and put on scale? "Hey, the lower is heavier than the upper!"

You can balance the pack yourself, discharge it to under 10% and slow charge it to 100% and leave it on the charger for a couple of days.

However, the rebalance might not solve your problem.

A sly person might find a way to cause an internal coolant leak in their pack. Of course that would cause immediate shut down of the car and it would not be drivable. "What, no, I didn't say anything."

I am sorry that you are having the problem with the car and wishing you the best of luck.
 
Heima said:
$500 to balance a pack? What are they going to do, take them out of the car and put on scale? "Hey, the lower is heavier than the upper!"
I've heard of 'balancing' before.
https://batteryuniversity.com/learn/article/bu_803a_cell_mismatch_balancing
And it has something to do with keeping cells of similar voltages in the same bank (group), so they are moved around a bit. Interesting tech I don't know much about.
 
Sorry, I guess the humor doesn't come through. I was mocking the stealership of charging $500 to do what the car already does. I also suspect that the stealership actually wasn't going to do anything for $500, that they were just BSing. The only way I know of to manually balance a pack, (and the fact the stealership used the singular pack, and not the plural packs for this cough, cough service) is to open a pack and hook up a charger to each cell, charging each to their maximum value. I don't think a dealer is going to do that.

In Forscan, there is a parameter to see what balancing state the vehicle is in. I have not watched it much, but of the eight different states, the only two I have seen are "denied by vehicle" and "initializing".
 
Heima, sorry I missed the humor. I'm normally OK at that.
As for the dealership balancing a pack, my impression is they never are allowed (by Ford) to open a pack. They can and do ship them off to a special Ford lab, possibly run by the original part maker (maybe LG Chem). Noticed that from a TSB recently.
 
When the dealership says "balance the packs for $500", maybe it could help a lot. Assuming they move individual cells around inside there until each bank (5 banks with 86 cells each) has about the same voltage and discharge characteristics. Of course, for a big range degradation like this situation, you would think some cells in there need replacing too.
https://en.wikipedia.org/wiki/Ford_Focus_Electric
 
triangles said:
You got that a little backwards. it's 86 groups of 5 cells each.
Are they grouped across parallel lines? I define a "group" as one set in series, 86 cells in series..... Each cell is 3.7v, and 86 of them wired in series gets us 318v total. Then there are 5 groups of those in parallel to support overall current (amp) flow & power needs (power is volts x amps).

Seems like in balancing, you want to get each parallel path (5) to have same voltage. Then, the sum of cell volts in each series set must be the same as the other 4.

Are you saying there are 86 modules, each with 5 cells, wired in stackable series? That would be the other way to define a "group" and would make sense if they package them that way. Have you opened one of these up?
 
There are 86 Groups of 5 parallel cells, wired in series. Or more simply in battery short hand: 86S5P

The way you worded it made it sound like you meant 5S86P. After rereading what you wrote I now understand that isn't want you meant.

Not using words like "bank" or "group" to clarify. The way batteries are made is that you have a number of cells wired in parallel and then these bundles of parallel cells are wired in series to get the desired voltage. In the case of the FFE we would start with multiple sets of 5 cells wired in parallel. Then you would string 86 of these sets together in series (86S5P). The way you describe it was as if there were 5 strings of 86 series wired cells that are then wired in parallel. While electrically that would be equivalent, it's just not how batteries are made. I believe that is where the confusion lies. Does this make any sense?
 
Triangle, and Heima's cat, thanks for thinking that over.
I had envisioned 5 "lanes" of current flow, basically independent from each other, except for the "+" endpoint and "-" endpoint which connects the lanes. Kind of like 5 highway lanes of cars bumper-to-bumper, front bumper is "+", rear bumper is "-", current flow forward on discharge, with only the cars in each lane touching each other (no cross-lane touching).

It appears each set of 5 cells have their + terminals connected together, and their - terminals respectively as triangles described. That must work better from a discharge and recharge standpoint.
Which brings me to balancing: If a cell is showing low voltage or high internal resistance, compared to what the other 4 cells are doing in parallel, it would diminish the energy storage ability a bit.

Figure 6 shows triangle's wiring method. Notice the connections that fuse together the positve and neg terminals across cells:
https://batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations
 
Not to be nit picking.... ok, I guess I'm nit picking here :lol: It would be impossible for one of the five cells to have a different voltage than the other four in a parallel group because the battery terminals from all 5 cells are electrically connected.

When it comes to cell balancing you are actually only balancing 86 groups of cells not all 430 cells individually as the for the reason mentioned above, each cell in a group of 5 parallel cells already have the exact same voltage.

I don't know how our FFE battery is designed to handle a bad cell as far as fusing, BMS, etc. I have wondered what would happen if cell went bad. I suppose as long as it wasn't a dead short the other cells in the group would pick up the slack and overall battery capacity would be reduced. I suspect the BMS would sound alarm bells as the voltage difference between cell groups increased as the battery discharged.

Someday if I ever find cells cheap enuff to rebuild my battery with a higher capacity I may find out how this all works. But I doubt that will ever happen.
 
Good posts all. I'm a little outside of my expertise here (Mech/Aero/C.Sci only please), though circuits are kinda interesting.

Getting to Olagon's potential (pun) $500 charge (pun) for balancing, what concerns me is if 1 of the 5 cells in a pack has a loop current running through it while the pack discharges. ... ("loop" = "circulating" current in the parlance)

"However, given the
differences in internal resistance, capacity, aging property, and temperature of cells, the discrepancy in
the state of charge (SOC) and/or voltage among the parallel batteries is inevitable [12–14]. As a result,
circulating current among batteries with different SOC and/or voltage is unavoidable."

https://www.mdpi.com/1996-1073/10/3/404/pdf for all the explanation I won't repeat here myself....
 
thanks for sharing. I'll have to give that a read. I'm pretty good with my circuits and basic electrical stuff, but I freely admit I have no idea what happens when there is an issue with one cell in a parallel group of cells.

Also back to the OP. I'm pretty sure the BMS will balance the cells if needed when plugged in overnight. I have no reference for this, I just assumed because that is one of the functions of a BMS is to keep the cells balanced. Sounds to me like the cell balancing fee is purely a scam by the stealership.
 
triangles said:
thanks for sharing. I'll have to give that a read. I'm pretty good with my circuits and basic electrical stuff, but I freely admit I have no idea what happens when there is an issue with one cell in a parallel group of cells.
Yep, I had to think about Kirchhoff principles too, and battery models in terms of ideal elements (capacitors, resistors, EMF source).
When a cell is bad, at a lower potential (volts) than the others, a current flows from the good batteries to the bad one. A cell can be internally damaged where it gets a different SOC and voltage during discharge and charge. Sure they are hooked up in parallel, yet current flows, down the voltage gradient along the short wire, due to an imbalance of volts in each cell.
DWSxy1V.jpg

.... from the link paper I posted previously, page 2.

triangles said:
Also back to the OP. I'm pretty sure the BMS will balance the cells if needed when plugged in overnight. I have no reference for this, I just assumed because that is one of the functions of a BMS is to keep the cells balanced. Sounds to me like the cell balancing fee is purely a scam by the stealership.
The active balancing the car does automatically may not be perfect, or down to the individual cell level. I'm trying to find out what ours does exactly.


This balancing stuff is interesting.
NREL has something to say about it to help us understand:
https://www.nrel.gov/transportation/battery-control-algorithms.html

Those NREL descriptions look at cell management, and make them seem "advanced" since on-going Ford etc. research has been happening. Much of that is being used in the Mustang EV coming.
Does anybody know if our Focus EVs have individual cell switches, like shown in the figure above and mentioned in NREL's summaries, or does balancing and managment only happen a group module at a time?.. ("group" defined as one set of 5 in parallel; 86 of those modules).
 
Ok, the cat is sleeping, so Ican try this again, but it will be much shorter this time.
My math, and it's verified by the photos in the teardown that I posted in "Something for the Enginerds" is that there are 360 cells total. 130 in the upper pack, 230 in the lower.
In the photos, we see that there are large 20-cell modules, and half sized 10-cell modules. In the upper pack are 6 full size and 1 half size in a single row. Thats 6x20 +10=130. In the lower pack, there is a row of 6 full size, and then a second row of 5 full size and 1 half size. Thats 6x20 + 5x20 + 10=230
So the total is 360.
But 360 is not whole number divisible by 86.
The teardown states that the full size module has a 5p4s arrangement, and that the half size has an 5p2s arrangement. While possible, I have a problem with this. It means that 10 cells have 1 terminal all bonded together. Look at the physical dimensions of the half size module. All 10 modules inside are bonded at the midpoint. How? From the teardown, the tabs of each cell look too short to reach from one end of the module to the midpoint.

Also this, lets consider that all of the modules are in series. That makes 17 full size modules and 2 half size modules. Lets say the 2 half size modules are equivalent to 1 full size module. If the battery produces 400v, just supposition here, then each full size module produces 400/18=22.22 volts. So it takes 4s to make 22.22, so each cell produces 5.5 volts. Um, no.

So what if we work backwards, and say that each cell produces 4 volts? Thats 4x4x18 = 288 Volts. Again, no. Thats not happening.

But what about the 86? In each full size module, there are 4 sets of 5 cells. There are 17 full size modules. 17x4 is 68. Not anywhere near 86.

But what if the arrangement was 4p5s in the full size module and 2p5s in the half size module? The person creating the report might not have fully understood battery arrangement and made that mistake. For compatibility, the half size modules would have to be wired in parallel. (who knows how that would work, they are in separate packs) Lets do the math again. 400/18=22.22 volts. 22.22/5 is 4.4volts per cell. Getting closer to reality. Working backwards, 4x5x18=360 "Well Gooollllyy Sargent Carter" it looks like we have winner.

So that seems good 4p5s, it is still a stretch to bond 8 cells together, but what about the 86? In each full size module, there are 5 sets of 4 cells. There are 17 full size modules, 17x5=85 Thats good, but there are the two half size modules, in separate packs, how do they add to be 1?

Dare we go 2p10s for the full size module and 2p5s for the half size module? Skipping to the math: 22.22/10=2.22volts, kind of odd for a lithium cell, going the other way 4x10x18=720Volts, too much, but what if we were to half the packs, meaning that we take both packs as one imaginary pack, and in that imaginary pack there are two rows, each putting out 360 volts, but in parallel with eachother?
So 18/2 =9 full size modules in each imaginary row. But we still have the 86 problem. Now two rows, so 43. 43/9=4.78 nope, needs to be a whole number.

86=86x1=43x2 I can't seem to find any other whole number factorials for 86.

Hmm, this seems like a dead end. There is this: What if the 86 isn't from 1 to 86, but 0 to 86? If it was, then there would be a total of 87, and the two extra (87-85=2) could be for the two half size modules.
 
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