Verdict of 2016 Model S 60 Battery being top or bottom limited?

[ab26]

Hi All,

I know this topic has perhaps been beaten to death, but after going through numerous post, I am a little unclear on the final verdict.

Majority of the folks here believe that the battery is being top limited. This is based on two facts - supercharging speed does not taper off till 100% and many Tesla service technicians mentioning that it is OK to charge to 100% without degradation.

However, there's a reputable engineer in this forum that thinks it's actually not the case and to truly confirm, we need to look for the logs of the car to see what the individual cell voltage is when a 2016 Model S 60 is fully charged. [see forum title - "Some exciting observations about the new Model S60 (software limited 75 kWh)"]

Can someone who's technically sound, comment on this? Do we really know if the battery is top or bottom limited.

 

[MP3Mike]

From what I have seen we don't have a verdict yet. @Ingineer hasn't posted in almost a month, I sure hope he comes back I miss his posts. (And would like an answer to this question.)

 

[outOfPhase]

I'm not "technically sound" but I'll tell you my view: the evidence I've seen so far isn't conclusive and so it comes down to what you choose to believe. What I personally choose to believe - knowing full well that it is an assumption - is that it's a bit of both, probably 5-85%, i.e. 5% limited at bottom and 15% at top. I choose to believe that because (a) that's what I'd do if I was the engineer as it provides the best protection all round for the battery, (b) it's consistent with the charging results I've seen and (c) I read somewhere that a split like this was used on the old 40 KwH model.

 

[MP3Mike]

I read somewhere that a split like this was used on the old 40 KwH model.

Actually the limit on the 40kWh cars was a complete hack. They just limited how high you could set the charge percentage to 68%.

 

[Frankman60]

I have a 2016 software limited MS60 and noticed the last time I charged to 100 percent at a SC the charge rate definitely slowed after 90 percent. I noticed it this time because I was in the car while it was charging.

 

[brkaus]

Also, any future firmware could change it...

 

[Shumdit]

I think it's top limited. It seems there would be a much needed more pronounced taper otherwise. My gut is that you can't charge it to it's true capacity. It could be somewhat bottom limited (more than all of the other battery sizes are) but I don't see why they would need to go through the trouble since the way it's set up for the other battery sizes works fine

 

[whitex]

I have a 2016 software limited MS60 and noticed the last time I charged to 100 percent at a SC the charge rate definitely slowed after 90 percent. I noticed it this time because I was in the car while it was charging.

Couple of questions:
1. When you do charge to 100%, is your regen disabled?
2. When you have it set to charge to 100%, does the car remind you to switch to lower target after a day or two?

 

[Frankman60]

Couple of questions:
1. When you do charge to 100%, is your regen disabled?
2. When you have it set to charge to 100%, does the car remind you to switch to lower target after a day or two?

1. I'm not aware that the regen is disabled after a 100 percent charging. What would indicate that regen is disabled?
2. I only charge to 100 percent when I need to, and then change the charge percentage back to 90 percent shortly thereafter. I have not received any reminders to lower the charge percentage because I lower it myself.

 

[whitex]

1. I'm not aware that the regen is disabled after a 100 percent charging. What would indicate that regen is disabled?

You'd see a yellow line on the regen side of the power meter (if you have it up on your cluster). If you drive with standard regen setting, you'd definitely notice that the car is not slowing down when you take your foot off the accelerator while the battery is close to 100% (first few miles).

 

[Frankman60]

You'd see a yellow line on the regen side of the power meter (if you have it up on your cluster). If you drive with standard regen setting, you'd definitely notice that the car is not slowing down when you take your foot off the accelerator while the battery is close to 100% (first few miles).

OK, thanks for that information. I don't normally have the power meter visible. But I do have the regen setting to standard and have not noticed any change in the regenerative breaking.

 

[CKCland]

regen is not limited when my refresh S60D is at 100%

 

[LastGas]

1. When I charge to 100% I do not observe regen disabled.
2. Yes you get the Nag screen every few days when you charge to 100%

The way you can be sure that charging to 100% is not the top of the battery is looking at what rate the car is charging when it reaches 100%. Charging is still going on at a good rate, and then stops abruptly at 100%, rather than creeping the last few percent.

Bjorn Nyland has a YouTube video of charging a 60D to 100%.

 

[whitex]

Thanks guys! You're helping me convince myself to pick up a 60D as a second car. Here is hoping solid white comes back tomorrow (with the rumored price increase, but maybe the price increase will include a change to a 65KWhr battery).

 

[The_Mike]

Couple of questions:
1. When you do charge to 100%, is your regen disabled?
2. When you have it set to charge to 100%, does the car remind you to switch to lower target after a day or two?

1. Regen is not affected at 100%.
2. You still get the annoying nag.

100% supercharging rate is 35kW, which is extremely high compared to an unlocked battery. I frequently supercharge to 100% when we're on trips because I don't like to be rushed at lunch!

 

[sandpiper]

Actually the limit on the 40kWh cars was a complete hack. They just limited how high you could set the charge percentage to 68%.

It probably acted as a bit of prod every time you charged... just letting you know that there was more that you could have. At a price.

 

[thewoz]

"1. Regen is not affected at 100%.
2. You still get the annoying nag."

Same here!

 

[⚡️ELECTROMAN⚡️]

Ok so regen isn't affected at 100%. Does it still show your range increasing while regening? I'm assuming it doesn't show the charge increasing to 100.1%. I live on top of a big hill, so I'll get to see for myself in a few weeks.

 

[ab26]

As much as all evidence translates to a 100% charge being not top limited,I am wondering why @Ingineer thinks otherwise. Ideally, we would like to measure the cell voltage at 100% for a final confirmation. Has anyone done that yet?

 

[DB 2]

First post after lurking for over a year:

Refreshed MS 60 RWD received in July -

First, I confirm as well that supercharging to 100% ends while still pulling 34-35 kW.

Perhaps more interesting - here's something I have not seen reported anywhere else - not only is regen fully available even at 100% SoC, but you can add significant charge on top of 100%. I charged to 100% and then drove down 4500 vertical feet over 18 miles. The IC gauge does not go above 100%, but rated miles (range mode off) went from 207 (my normal 100% at the time) to 217. The Since last charge trip odo showed -3.3 kWh. The IC gauge dropped to 99% only after 33 miles since last charge (those last 15 miles were still slightly downhill).

Regarding the original subject, I still can't prove it, but my money is on a two-thirds, one-third split (approx.) on the locked-out portion of the battery (2/3 top - 1/3 bottom). I think it is reasonable to assume that the point that an unlocked 75 crosses the 35 kW level on its taper while supercharging would show where 100% is in the locked 60. I predict that crossover point will be at 89-90% SoC on the 75. Now all we need is someone with a 75 to show and/or tell about its taper curve when supercharging into the low 90's percent SoC. Of course, even better would be someone unlocking their 60 and carefully observing how their charge level changes, but I'm guessing those will be few and far between.