90% Charge (Better for the HVB) vs 80% charge (more economical)

[SteelMach]

Hey all, new owner here.

Has anyone actually been able to get their Mach-E to charge to something other than 100%?

I configured FordPass to add my home address and save my preference at 80% SoC for the charge limit... but every time I plug it in, it goes to 100% regardless.

I don't see a way to do this from inside the vehicle, like in other EVs I've driven... am I missing something? I'd rather not keep going to 100% when not needed for daily use.

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[EVer]

Here's the passage from the manual.

I believe the key point there is that it isn't set to 100% routinely. 90% isn't the ideal storage SOC.

 

[ChasingCoral]

The tricky thing about battery degradation is that everything matters, just by different amounts. So the question is usually “does it matter enough for me to care”.

If you intend to keep this car more than 15 years, and you enjoy being fastidious with your cars (have you ever sent an oil sample from one of your ICE vehicles into a lab for analysis?), then there are all sorts of little things you could do to wring a few more cycles out of the battery.

However, for most people, just the basic rules of “leave it plugged in at home and only charge over 90% on days when you’ll need it” will do the trick.

That said, with L2 chargers there is going to be very little degradation difference between the available powers. Even a 48A charger is only 0.1C charge rate for the ER battery which is very gentle. I would have no concerns about leaving an L2 charger at full power.

Back when batteries were much smaller, that charger could be something like a 0.33C on a 30kWh battery, which might be higher than desired.

And again, technically you’d get a teeny bit less degradation if you backed the power off a little, but I think the potential gains are very small and not worth futzing with. How high of an SOC you charge to every night, and how many miles you drive per year will make a much bigger impact long term.

So do you see any need to periodically charge to 100% to force the cells to balance?

 

[Woeo]

Saving a measly 10 cents every night over the course of a year will save $36.50 over the course of a year. That is like getting a few free "fill ups."

10 cents will buy me most of a kilowatt hour. 10/14 = ~ 70% or .7 kWh

The MME battery is ~88 kWh usable, so going from 70-80% or 80-90% should require 8.8 kWh for either interval.

Are you suggesting that:

70-80% requires 8.8 kWh + efficiency losses

while

80-90% requires 8.8 kWh + efficiency losses .7 KWh greater than the efficiency seen from 70-80%

That would be an additional 8% in lost efficiency over the interval. Seems suspect.

 

[phidauex]

So do you see any need to periodically charge to 100% to force the cells to balance?

No. I'm not sure what the minimum balancing SOC is for these batteries (I'm sure we'll figure it out when we start getting data off the CAN bus), but for similar batteries that I use, 80-85% is plenty to start balancing, so my guess is that the 90% reported SOC will still allow for any needed balancing.

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