Go times and Value charging dependent on TCU?

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triangles

Well-known member
Joined
Aug 16, 2011
Messages
1,232
Location
Toledo, Ohio
I had planned on removing my TCU when free MFM expires to eliminate some of the drain on the 12V battery when the car is off. Out of curiosity I pulled the fuse for the TCU to see if anything else would stop working. Since I couldn't talk to the car any more via MFM I got the right fuse. It's in the fuse block on the driver's side in the rear hatch area. The 5A fuse in the bottom right hand corner in case anyone is wondering. Anyway. I've noticed that "GO times" and "Value charge" no longer function. You can't even change any setings like if you wanted to setup GO times. It simply won't let you enter anything. If you had value charge settings enabled before pulling the fuse those settings will appear to be there but you cannot change anything and the car will default to "charge now" even though it says it will value charge at whatever time you had set it to. I pulled the 12V battery thinking it was a glitch and I just needed to "reboot" things. Well after rebooting the screen showed neither "value charge" or "charge now" as selected and still could not change any settings. Plugged in and sure enough it immediately started charging. So am I missing something or does the car need the TCU for some strange reason for "GO times" and "Value Charge" to function? Seems really odd unless Ford did something stupid and it relies on ford's MFM servers to function. That would be a really dumb way to handle "GO times" and "Value Charging."
 
I think that they put the go times and value charging functionality in the TCU to minimize the # of modules that do need to stay alive when the car is off since the TCU does stay alive (so MFM can talk to it).
 
Huh... I would have though they would have put that in the RFA module since that never powers down and already has remote start and lock/unlock functions. I'm willing to bet money that the RFA in the FFE is the same as the ICE focus so maybe it was easier to keep the RFA the same across all Focuses and just put the FFE specific charge settings and GO times in the TCU. Especially since you need the TCU for these functions when using MFM.

I had MFM set to text me when the car is fully charged and I recently started using Value charging to finish charging right before I get up in the morning to minimize the time the battery sits there full. That quickly got annoying being woken up an hour or two early by a text from my car being fully charged. If only I could set it not to message me at o-dark 30 in the morning I would keep this alert active.
 
triangles said:
I had MFM set to text me when the car is fully charged and I recently started using Value charging to finish charging right before I get up in the morning to minimize the time the battery sits there full. That quickly got annoying being woken up an hour or two early by a text from my car being fully charged. If only I could set it not to message me at o-dark 30 in the morning I would keep this alert active.
I have MFM setup the same for both my C-Max and the FFE but I don't have it set to text me; I'm using the in-app messaging and have the phone muted overnight (do-not-disturb times).
 
Sorry, I'm not an engineer, but a FFE owner.

I have greatly discounted charging 10PM - 6 AM. so i always start at 11:00PM, done by 1:30 am. I leave for work at 7:15 am

Is it a problem to have your battery at 100% for a length of time?
 
I am an engineer but not a EV or even battery expert so being an engineer has little to do with it :lol:

The quick answer to your question is: No. It is not a problem for your battery to sit fully charged. When your car says 100% charge it's actually about 90% charged. and I don't remember what the low end cut off is but I think it's about 5% charge when the car shows 0%. The FFE has some built in "protection" for battery longevity by preventing a full charge or discharge.

The little knowledge I have about the FFE's NMC Lithium batteries or lithium batteries in general is that they don't like to be fully charged or fully discharged. Deeply discharging and leaving them at this state is much more detrimental to battery longevity than leaving it in a fully charged or nearly fully charged state. A battery expert familiar with our battery chemistry could probably tell you what the best SOC (state of charge) range to keep the battery in for longevity. I'm going to guess it's something like 40%-60% or maybe 40%-80%. I'm probably a little high on the low end.

The short distances I usually drive allow me to rarely deplete the battery below 40% before charging. I generally try to avoid letting it go below 20% but I don't fret the handful of times a year I have to use nearly all my capacity since that isn't likely to cause much degradation. I do however ensure that whenever I do run it nearly out of juice that it is plugged in a charging at my destination so it's at a very low SOC for as short as possible. On the flip side I only use value charging to delay charging until right before I am likely to need the car again. If it's much below 40% I usually switch to charge now since leaving it at a low SOC is more detrimental than leaving it sit fully charged. However 100% fully charged in our case is in reality 90% SOC which adds a margin of safety on the high end.

I guess what I'm getting at is with the "buffer" already built in by Ford, leaving it fully charged all the time vs waiting to fully charge until right before you will need it again probably would have a negligible difference in battery degradation. However, always letting the battery sit for hours every day at very low SOC waiting to value charge instead of charging immediately upon arrival probably would result in a measurable battery degradation. As I mentioned early I'm not a battery expert so I don't have the knowledge to put any sort of numbers to my musings. I only know what I read on the internet! :lol:
 
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