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P85D Vbox guys -- anyone test to see if "Max Battery Power" changes anything?

cynix

Member
Jul 7, 2014
829
247
Sydney, Australia
Can anybody explain what this max battery mode is and I use it?

Max Battery Power mode heats up your battery so that it can produce higher output in a short burst. However it causes battery degradation and will reduce the longevity of your battery, so Tesla advises that it should be used sparingly.
 

ArtInCT

Always Learning
Sep 2, 2014
1,713
433
Southern Connecticut
However it causes battery degradation and will reduce the longevity of your battery, so Tesla advises that it should be used sparingly.

Hi Cynix: That is some interesting information. Can you please post a link as to where you read this from Tesla Motors? If you are on shore power, does the heating energy come from the shore power or the main traction battery pack? I will be getting a P90DL and would like to be "up" on the guidelines and warnings.... and how that actually works... thanks.

ARTinCT
 

cynix

Member
Jul 7, 2014
829
247
Sydney, Australia
Hi Cynix: That is some interesting information. Can you please post a link as to where you read this from Tesla Motors? If you are on shore power, does the heating energy come from the shore power or the main traction battery pack? I will be getting a P90DL and would like to be "up" on the guidelines and warnings.... and how that actually works... thanks.

ARTinCT

Please see more information here: Max Battery Power setting in P90DL

I'm still waiting for v7.0 for my P85D, so I don't really have any first-hand knowledge :)
 

LetsGoFast

Active Member
Oct 13, 2014
1,329
101
Virginia
Please see more information here: Max Battery Power setting in P90DL

I'm still waiting for v7.0 for my P85D, so I don't really have any first-hand knowledge :)

I do not believe that that the warning is intended to say that it will reduce battery life or cause degradation to the cells. I believe they are simply saying that you will consume electrons at a more rapid rate and that the battery will enter reduced power mode faster due to overheating more quickly.

- - - Updated - - -

i have 7.0 on my P85D and I'm pretty sure I haven't seen this option, I'll check again.

I got it on 7.0 and tried it out, but my butt dyno didn't detect any performance difference.
 

cynix

Member
Jul 7, 2014
829
247
Sydney, Australia
I do not believe that that the warning is intended to say that it will reduce battery life or cause degradation to the cells. I believe they are simply saying that you will consume electrons at a more rapid rate and that the battery will enter reduced power mode faster due to overheating more quickly.

Ah, that's good to know. Thanks for correcting my understanding.
 

wk057

Senior Tinkerer
Feb 23, 2014
5,655
11,383
Hickory, NC, USA
I do not believe that that the warning is intended to say that it will reduce battery life or cause degradation to the cells. I believe they are simply saying that you will consume electrons at a more rapid rate and that the battery will enter reduced power mode faster due to overheating more quickly.

I disagree. Heating the cells while they're at high states of charge definitely does cause accelerated degradation. This is a well known fact of the cell chemistry. Unless the pack is below a safe operating temperature I would never heat the cells.
 

ArtInCT

Always Learning
Sep 2, 2014
1,713
433
Southern Connecticut
I disagree. Heating the cells while they're at high states of charge definitely does cause accelerated degradation. This is a well known fact of the cell chemistry. Unless the pack is below a safe operating temperature I would never heat the cells.

Do you think that perhaps the MAX POWER function may take into account the current pack operating temperature and know, based upon that data point, that it does not have to heat the pack? For instance if the pack environment system was cooling the pack down already? Your thoughts? Or am I expecting too much from Tesla engineering??
 

AWDtsla

Active Member
Mar 3, 2013
4,262
3,952
NE
I disagree. Heating the cells while they're at high states of charge definitely does cause accelerated degradation. This is a well known fact of the cell chemistry. Unless the pack is below a safe operating temperature I would never heat the cells.

But how hot. If it's no worse than a summer's day, then it's no worse than driving your car in LA vs Montreal.
 

wk057

Senior Tinkerer
Feb 23, 2014
5,655
11,383
Hickory, NC, USA
Do you think that perhaps the MAX POWER function may take into account the current pack operating temperature and know, based upon that data point, that it does not have to heat the pack? For instance if the pack environment system was cooling the pack down already? Your thoughts? Or am I expecting too much from Tesla engineering??

Based on other's posts it does seem to take the current temperature into account. I'm assuming max power is just a high pack thermostat set point.

But how hot. If it's no worse than a summer's day, then it's no worse than driving your car in LA vs Montreal.

Don't know. Doesn't matter though. Hotter at high SoC = more degradation. So, a pack in LA will degrade more than a pack in Montreal, although Tesla's heating and cooling system should negate a lot of this under normal conditions. The max power heating function seems to go beyond this.
 

Ldub22

Member
Mar 1, 2015
173
131
Kirkland, WA

wk057

Senior Tinkerer
Feb 23, 2014
5,655
11,383
Hickory, NC, USA
Actually, Tesla/Panasonic's NCA chemistry is pretty tolerant of high temperatures... here's the research paper, examine the 2nd graph:

Development of High Power and Long Life Lithium Secondary Batteries

Note that the life cycle difference at 25 degrees C and 50 degrees C is roughly the same.

This paper has the same flaw that most battery related studies have. They simply charge and discharge repeatedly and think that's valid data. Unfortunately that's not how things work in the real world.

Instead of charging to 100% and then immediately discharging at a high rate, we tend to stay at or near 100% longer and discharge more slowly.

If you haven't watched this video, you probably should: Why do Li-ion Batteries die ? and how to improve the situation? - YouTube
 

LetsGoFast

Active Member
Oct 13, 2014
1,329
101
Virginia
I disagree. Heating the cells while they're at high states of charge definitely does cause accelerated degradation. This is a well known fact of the cell chemistry. Unless the pack is below a safe operating temperature I would never heat the cells.

Well, there are two different issues. One is what Tesla's statement actually says, which does not say that you will experience degradation. I'm pretty confident of that.

The second issue is the question of whether or not Tesla allows the batteries to heat beyond a point where the cells will deteriorate and whether or not Tesla takes state of charge and other operating parameters into consideration. Although I certainly agree that it is possible to overheat the cells, we actually have no evidence to suggest that this is what takes place when you activate the function. In fact, we have very little evidence to suggest much of anything about its function. It is well-known that LiIon batteries perform poorly at lower temperatures and that damage occurs most often at high states of charge and high temperatures. There is a lot of room in the middle.
 

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