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Abnormal battery behaviour?

steilkurve

Member
Mar 28, 2015
877
277
Montreal, Canada
Hey all. The battery in my 2017 X100D has degraded fast over the summer.

At delivery over 3 years ago, it was briefly at 295 before dropping to 292 and staying there for a while.

It then lowered progressively until it reached 283 last spring. Over the summer, it lost another 11 miles. It’s now sitting at 272.

I tried the much talked about calibration (down to 5% and back up to 100% a couple of times). I gained a couple of miles only to loose them again shortly after.

A few other bits of info:

- Car has 27K on it
- I plug in every night and charge to 90%
- I tow with the X so during the summer months, I charge to 100% a bit more frequently, maybe 3-4 times a month on average.

Finally, I’m seeing increased vampire drain. Car sitting inside and plugged in can loose over 10 miles in two days.

Do folks think I’m just a victim of the imprecise displayed range algorithms or is there something off with the pack?

Thanks in advance.
 

mxnym

Member
Mar 9, 2018
887
325
Bloomington, IN
295-272=23
23/295=0.07796610169491525423728813559322

While the calculation or measurement could be off, even if it is real degradation, 8% degradation might be slightly higher than typical, but I don't think it's significant enough to be considered problematic.

Regarding the vampire drain, that is likely a separate issue, possibly related to an update or some other change.
 

steilkurve

Member
Mar 28, 2015
877
277
Montreal, Canada
While the calculation or measurement could be off, even if it is real degradation, 8% degradation might be slightly higher than typical, but I don't think it's significant enough to be considered problematic.

Thanks.

Should I try the 'draining to 5% / charging to 100%' routine a few more times, though I get both extremes are not good in general?

Regarding the vampire drain, that is likely a separate issue, possibly related to an update or some other change.

I dont have TeslaFi or anything constantly turning the car on. I wonder if it couldn't be the upgrade to MCU2 and something not being done correctly there.

Only other thing I can think of is I recently added an SSD drive for DashCam. I do turn off Sentry mode while at Home automatically but I wonder if the SSD drive stays on?
 

mxnym

Member
Mar 9, 2018
887
325
Bloomington, IN
Should I try the 'draining to 5% / charging to 100%' routine a few more times, though I get both extremes are not good in general?
Personally, I changed my battery display to % as soon as I got my X. I have since seen several people recommend exactly that when threads similar to this come up. AFAIK, the battery management system can tell the charge level of the battery and will maintain the battery appropriately regardless of whether or not auxiliary systems are appropriately estimating battery capacity, so there is no benefit to the recalibration routine.
I dont have TeslaFi or anything constantly turning the car on. I wonder if it couldn't be the upgrade to MCU2 and something not being done correctly there.

Only other thing I can think of is I recently added an SSD drive for DashCam. I do turn off Sentry mode while at Home automatically but I wonder if the SSD drive stays on?
I have seen some reports of MCU2 upgrades leading to increased vampire drain here and/or on reddit, and others have chimed in that they also got an MCU2 upgrade and don't have the problem. I wouldn't rule it out, but I'm not sure what you'd do to resolve it if that is the case.

Regarding the SSD, the USB ports power down as far as I know, so I'm not sure how it could stay on in that scenario. That isn't to say that it couldn't be keeping the MCU from sleeping and thusly keeping the USB ports from powering down, but I think it's safe to say that it shouldn't. Regardless, it presumably wouldn't hurt to leave it unplugged for a couple days to see if it makes a difference.
 

steilkurve

Member
Mar 28, 2015
877
277
Montreal, Canada
Personally, I changed my battery display to % as soon as I got my X. I have since seen several people recommend exactly that when threads similar to this come up.

I do that too, but not in summer. When I tow, it’s easier to estimate if I have enough range left with miles than with %.

What do you charge to every day?
 

mxnym

Member
Mar 9, 2018
887
325
Bloomington, IN
I do that too, but not in summer. When I tow, it’s easier to estimate if I have enough range left with miles than with %.
I don't tow, but I always have the energy chart up on the MCU. I would think that having it up on "average" over 30 miles would give you a much better estimate than EPA miles or percentage.
What do you charge to every day?
I charge to 80%. My current commute brings it down to 60%, and I schedule it to charge at a set time in the AM so that it finishes shortly before I leave in the morning. When I have a longer round trip planned, I bring the charge limit up before departure.
 

steilkurve

Member
Mar 28, 2015
877
277
Montreal, Canada
I don't tow, but I always have the energy chart up on the MCU. I would think that having it up on "average" over 30 miles would give you a much better estimate.

True that and good point. I refer to it from time to time. Mostly though, I have the backup camera on to monitor the hitch and connections to my travel trailer. That being said. I’ll go back to displaying % I think and maybe try to bank on the energy app.

I charge to 80%. My current commute brings it down to 60%, and I schedule it to charge at a set time in the AM so that it finishes shortly before I leave in the morning.

I’ll try lowering my charge limit. Did that back when I had my S (70% it was) and it messed up the EPA estimate. Think the SvC at the time suggested 90% would stabilize things. Could the fact I’ve kept charging at 90% and let the car sit there (working from home during the pandemic) affected the battery?

And thanks for all your insights!
 

mxnym

Member
Mar 9, 2018
887
325
Bloomington, IN
While some might suggest setting the charge to 50% if the vehicle is going to be parked for a long time, I can't imagine that there is any significant risk to the battery as the vehicle sits while the charge is anywhere between 10% and 90%.
 

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