Should I be Worried ? SOH 79%

[ZSC100]

Doesn't Ford specify 22 days for full learning and calibration? I highly suggest a gentler approach. I would not try to push zero with an unbalanced battery, it will stop operating when the lowest voltage reaches threshold, even if estimated capacity is still some soc>0.

You're worries are warranted, but no-one fully understands all the algorithms Ford or it's vendors implemented within the BMS. I have personally experienced this several times and tested it. Until you run the battery to what the vehicle considers zero it retains uncertainty of the full capacity and that shows within the SoH. For the OP I'd suggest running it down to 5% with normal in-town driving, then staying close to home on a route that's flat and when he gets to zero, drive straight back home. It's very unlikely that he would end up with a completely inoperable truck and not be able to make it back home on 3% limit. If he even gets that limitation at 0% SoC.

We do need to see his module variation % to understand if he's got at least a somewhat healthy balance going on and then as he runs it down to 0% how the the Module Mariation tracks. If he charges to 100% and has a decent Module Variation, say, less than 2% @ 100% then as he goes to zero that doesn't climb to over 10%, I'd expect his SoH to correct to over 90%. If he can't get his SoH above 85% given the miles he has currently I truly think he needs to demand a buyback or full battery replacement. Which I can help navigate.

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[mb0220]

You're worries are warranted, but no-one fully understands all the algorithms Ford or it's vendors implemented within the BMS. I have personally experienced this several times and tested it. Until you run the battery to what the vehicle considers zero it retains uncertainty of the full capacity and that shows within the SoH. For the OP I'd suggest running it down to 5% with normal in-town driving, then staying close to home on a route that's flat and when he gets to zero, drive straight back home. It's very unlikely that he would end up with a completely inoperable truck and not be able to make it back home on 3% limit. If he even gets that limitation at 0% SoC.

We do need to see his module variation % to understand if he's got at least a somewhat healthy balance going on and then as he runs it down to 0% how the the Module Mariation tracks. If he charges to 100% and has a decent Module Variation, say, less than 2% @ 100% then as he goes to zero that doesn't climb to over 10%, I'd expect his SoH to correct to over 90%. If he can't get his SoH above 85% given the miles he has currently I truly think he needs to demand a buyback or full battery replacement. Which I can help navigate.

Is it pointless to charge up to 100% for rebalancing if you don't first discharge to 0%?

 

[ZSC100]

No, in fact you should do it the other way. Letting the vehicle charge to 100% attempts to balance all the cells. It's not well understood exactly how they are balancing, but it's some kind of passive balancing scheme, so charging to 100% after driving down the battery to at least 80% multiple times will probably get you good and balanced at the top end. My truck gets sub 1% Module variation every time I charge to 100%

Then, as you run the battery down to zero, picture a graph showing the SoC on bottom 100% on the left and 0% as you move to the right (as time travels to the right as you discharge) and SoH on the left. What would be ideal is to see the SoH remain perfectly flat,, sub 1%, all the way down to 0% SoC. Technically, you are limited in overall series pack capacity by your worst performing cell. Basically the first cell group to discharge to the voltage threshold set by the designer will cause your BMS to indicate 0% SoC no matter how much energy is sitting in any of the other cells groups.

So, this is why it's important to look at your Module Variation at 100% SoC and 0% SoC. Hopefully the OP can get this posted here ASAP.

 

[mb0220]

No, in fact you should do it the other way. Letting the vehicle charge to 100% attempts to balance all the cells. It's not well understood exactly how they are balancing, but it's some kind of passive balancing scheme, so charging to 100% after driving down the battery to at least 80% multiple times will probably get you good and balanced at the top end. My truck gets sub 1% Module variation every time I charge to 100%

Then, as you run the battery down to zero, picture a graph showing the SoC on bottom 100% on the left and 0% as you move to the right (as time travels to the right as you discharge) and SoH on the left. What would be ideal is to see the SoH remain perfectly flat,, sub 1%, all the way down to 0% SoC. Technically, you are limited in overall series pack capacity by your worst performing cell. Basically the first cell group to discharge to the voltage threshold set by the designer will cause your BMS to indicate 0% SoC no matter how much energy is sitting in any of the other cells groups.

So, this is why it's important to look at your Module Variation at 100% SoC and 0% SoC. Hopefully the OP can get this posted here ASAP.

Thank you for bearing with my non-engineer understanding... So then would it be correct to say that charging to 100% is what gets you the benefit of the rebalance, and the discharging to 0% is how you test how balanced the battery is?

 

[ZSC100]

Thank you for bearing with my non-engineer understanding... So then would it be correct to say that charging to 100% is what gets you the benefit of the rebalance, and the discharging to 0% is how you test how balanced the battery is?

Balancing is the process of trying to bring all the 90+ cell groups to the same voltage. Slight differences in various cell characteristics are always working to hurt the balance of the battery. So, continued balancing is ALWAYS necessary. In general, you can't balance a battery while it's in use or while charging over a certain rate, this is why the system slows WAY WAY down in charge rate as it approaches 100% SoC That allows the BMS lots of time to balance the cell groups. So, even though you balance your battery when you charge to 100%, as soon as you start driving your battery starts to lose its balance. The health of the battery is directly related to how quickly your module gets out of balance as they discharge. It is very likely that the BMS does ZERO balancing effort during discharge or DCFC. Even if it does, it's not very effective b/c of the rate capabilities. So, your BMS does balance every time you L2 Charge, but if you only charge to 80 or 90% there's only so much it can do every day. That's why it's it's good practice to charge to 100% every few weeks, or at least every month.

 

[Adventureboy]

79% SOH seems low to me, but how many miles do you have on it and how much charging do you do on DCFC vs L2?
Like others have said, recalibrate the pack:

1. Charge to 100% (make sure it gets to 100% plugged in, not just 99% - it can take a couple of hours to go from 99-->100% if they are out of balance). Give it a couple of hours at 100% to settle and top up the balancing
2. Drive down to about 10-15% (can be done over several days)
3. Charge to 90% and resume normal charge habits
4. Check SOH again and see where it is.

This calibrates the whole pack and removes anomalies that accumulate by use/charge patterns. If you see an improvement in SOH, you may want to do the process a second time. The balancing process is limited in capacity and time, so a second round may be needed for a pack that is out of balance.

 

[Mpi]

79% SOH seems low to me, but how many miles do you have on it and how much charging do you do on DCFC vs L2?
Like others have said, recalibrate the pack:

1. Charge to 100% (make sure it gets to 100% plugged in, not just 99% - it can take a couple of hours to go from 99-->100% if they are out of balance). Give it a couple of hours at 100% to settle and top up the balancing
2. Drive down to about 10-15% (can be done over several days)
3. Charge to 90% and resume normal charge habits
4. Check SOH again and see where it is.

This calibrates the whole pack and removes anomalies that accumulate by use/charge patterns. If you see an improvement in SOH, you may want to do the process a second time. The balancing process is limited in capacity and time, so a second round may be needed for a pack that is out of balance.

This.

And be patient with SOH. My own experince was that balancing will show up as small improvements in SOC variation and Voltage variation, and a couple of charge cycles later the SOH would bump up incrementally. Remember that SOH is an estimate constructed by a computer inside your battery, not a mechanical measurement. That computer likes to be cautious about your battey's true capacity (which SOH reflects). It like to be cautious to protect you from being stranded by a dead battery.

Please post SOC Variation, Voltage Variation, and [BECM] Battery Capacity.

 

[Tpear]

So i have charged it to 100% and discharged to 2%. Recharged it to 100%. No effect, prior to that exercise it went up to 81% from 79%.

so just be patient I guess.

 

[ZSC100]

what is your "Energy Remaining" at 100% SoC I'm curious if that lines up with 81% of what your batter should be?

 

[Mpi]

Your battery age tells me that your BECM itself was replaced. Variations aren't too bad, I think you'll slowly get SOH back of the next couple of months as the new BECM learns the battery.

 

[Zprime29]

Your battery age tells me that your BECM itself was replaced. Variations aren't too bad, I think you'll slowly get SOH back of the next couple of months as the new BECM learns the battery.

That caught my eye as well.

The truck thinks that battery is basically brand new, less than a month old. Ford reps have mentioned here that it takes several weeks for the BMS and battery to get back fully in sync. I would give it a month or two and then see where things settle.

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