Charging time 90 to 100 and Departure

[Wendy]

We regularly take a trip over the mountains, and I try to charge to 100% before we leave. For safety and to exercise the top end of the battery. I recently saw a comment in a thread (can’t find it or I would reply there) about the time it takes for the last few %. So I thought I would watch today.

I have a ‘23 Lariat ER, and FCSP 100amps, so it charges about 10% per hour.
We plan to leave at 10, so I started the charge (from 90%) at 8:00. It said it would hit 100% by 10:23. A while later I decided to set a 10:00am departure time.

at 9:00 it says the cabin temperature is ready (an hour early?). And I’m at 99%. But that last 1% will now take me until 10:42am!

I guess those last few electrons are running around the battery parking lot trying to find those empty spots.

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[RLXXI]

at 9:00 it says the cabin temperature is ready (an hour early?)

Time changed last night, or more accurately, this morning.

 

[PJnc284]

Balancing everything can take a while. I've had it take 1hr+ to go from 99%-100% but I don't charge to 100 much.

 

[fhteagle]

According to my investigations with an OBDII reader and Car scanner app, the difference between where my ER battery indicates 99% vs 100% is between 4 and 5 kWh. Also takes about 4 kWh used before the displayed SOC comes back down off of 100% to 99%. The rest of the percentage steps are arround the ~1.3kWh you'd expect, but that top step is a doozy as they say.

 

[chriserx]

i only have the mobile charger, but due to the way EVSEs work I'm fairly confident it would do it on any charger. That last 1% on mine charges at like 1-1.2 kw which is effectively level 1 charging. The only real curiosity is that it did that at all, the FSCP has more than enough overhead that it should've been able to provide enough power to do both simultaneously. Without knowing the exact charging schematic or programming logic, I'm inclined to think it is a small programming error on Ford's part. That being said if an extra 1-1.5 kwh is going to make or break your trip, you're using it wrong
Edit: I did forget that 99-100 is annoyingly more than 1% of the actual charge, but still.

 

[Firn]

What happens is the charger slows down massively as it balances the cells. In fact your comment about those last few electrons running around looking for spots is actually very correct. When its near full many of the cells are charged full, so now its charging just the cells that are lower, over time more and more of those fill, leaving fewer and fewer to absorbed the energy and so charging keeps slowing

 

[RickLightning]

Balancing everything can take a while. I've had it take 1hr+ to go from 99%-100% but I don't charge to 100 much.

Yup. And, it will use more energy than you think, like 10kW more. For example, with 10% left you would think it would take 13kW more, and it takes say 23kW.

 

[carys98]

Here’s a graph of my truck going from 80-100%. The scale is kW from the charger.

 

[Adventureboy]

It is true that the last 1% can take up to 3 hours (usually less). It is a very slow process to balance the cells since it is such a low voltage differential.

Interesting to see that your departure preconditioning happened before you hit your SOC of 100%. That is a good step forward. Originally on my 2023, if I set SOC to 100%, departure preconditioning would sometimes not happen because SOC takes priority, and if it didn't hit 100% with enough time to do the departure process, it would just drop it. The fix at the time was to drop SOC to 95% so it didn't take 3 extra hours to get to 100%. If you hit 99% and departure preconditioning happened, then Ford fixed that.

 

[topher10]

Is it still considered best practice to periodically (2-4X per year) charge to 100%?

Reading this information indicates its somewhat energy wasteful to charge to 100%, but at the same time we cannot set it to 98%. I only charge to 80% unless I am going on a long trip and know I need max battery, which is probably 5 times a year.

 

[jeep2liberty]

Unsure why Ford will not let us Lightning owners set our desired SOC to a specific percentage such as 55%, 99% etc. I also would like to know if a few times per year to charge to 100% is beneficial in any meaningful way for the battery health. I have never charged to 100% yet on the 2025 ER. Should I?
I assume it would be best to do this occasional 100% calibrating in cooler weather, say 50 - 60F ish. (?)

 

[Adventureboy]

Unsure why Ford will not let us Lightning owners set our desired SOC to a specific percentage such as 55%, 99% etc. I also would like to know if a few times per year to charge to 100% is beneficial in any meaningful way for the battery health. I have never charged to 100% yet on the 2025 ER. Should I?
I assume it would be best to do this occasional 100% calibrating in cooler weather, say 50 - 60F ish. (?)

Ford lets you set SOC to a specific % in 5% steps. Unfortunately, that means 99% is not an option, but 55% and 95% are.

Yes, it is beneficial to charge to 100% periodically. The charge from 99% to 100% balances the cells in each module and across the pack, so the maximum capacity of the pack can be reached for the current health of the pack. Charging to lower amounts, like 70%, 80% or even 90% too often can cause the cells to drift out of sync and reduce the overall capacity of the pack. (weakest link). This is especially important if you DCFC regularly, since fast charging to 80% can cause the cells to drift out of sync faster. You need to let it complete the charge to 100% before unplugging to allow the balancing to complete. It will sit at 99% for quite a while - sometimes for up to 3 hours. If you unplug it at 99%, the SOC meter will jump to 100% but the balancing process will not have completed. Not a big deal, but you want to let it fully complete all the way to 100% periodically. I aim for once per month.

 

[Firn]

Ford lets you set SOC to a specific % in 5% steps. Unfortunately, that means 99% is not an option, but 55% and 95% are.

Yes, it is beneficial to charge to 100% periodically. The charge from 99% to 100% balances the cells in each module and across the pack, so the maximum capacity of the pack can be reached for the current health of the pack. Charging to lower amounts, like 70%, 80% or even 90% too often can cause the cells to drift out of sync and reduce the overall capacity of the pack. (weakest link). This is especially important if you DCFC regularly, since fast charging to 80% can cause the cells to drift out of sync faster. You need to let it complete the charge to 100% before unplugging to allow the balancing to complete. It will sit at 99% for quite a while - sometimes for up to 3 hours. If you unplug it at 99%, the SOC meter will jump to 100% but the balancing process will not have completed. Not a big deal, but you want to let it fully complete all the way to 100% periodically. I aim for once per month.

Pack batteries should have internal balancing so over time the cells will balance even if not charging to 100%. I don't know the specific details for the Lightning but on other systems I have seen the balancing current is quite low.

Maybe this is one of those tech things Brian @Ford Motor Company can get for us.

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