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Wiki Sudden Loss Of Range With 2019.16.x Software

gmo43

Member
Jun 24, 2014
351
567
Mesa
Interesting. However, I'll bet many now avoid charging to more than 78%, because the pumps come on at 100%.

Even fewer charge to much over 90% because of the time it takes, and the loss of regen.

Dye to the asymptotic behavior of the voltage/SoC curve, does not take much to bleed off a tenth of a volt.

My guess is if you charge to 90% or less, not a problem unless you start at the top of a big hill.
My pumps run till empty if i let it happen.
 

gmo43

Member
Jun 24, 2014
351
567
Mesa
Yeah, but this is affecting "60" pack cars and I bet they need to charge to higher SoC due to their smaller pack sizes. So those owners may charge to a higher SoC more often just to make it from point A to B. And those are the packs that have a more limited warranty:
"Your vehicle’s Battery and DriveUnit are covered under this Battery and Drive Unit Limited Warranty for a period of 8 years,unlimited miles/km, with the exception of the 60 kWh battery which is covered for 8 years or125,000 miles/200,000 km, whichever comes first"

Very strange findings indeed o_O
I doubt any of those 60 are still under warranty. So I'd say definitely testing dummies
 

Droschke

Active Member
Mar 8, 2015
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4,425
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Interesting. However, I'll bet many now avoid charging to more than 78%, because the pumps come on at 100%.

Even fewer charge to much over 90% because of the time it takes, and the loss of regen.

Dye to the asymptotic behavior of the voltage/SoC curve, does not take much to bleed off a tenth of a volt.

My guess is if you charge to 90% or less, not a problem unless you start at the top of a big hill.

Yesterday, I AC charged from 48% to 50% and my fans/pumps ran the whole time. This has happened before and I posted here about it.

Since the time I got capped, I do not charge beyond 50% anymore.
 

aerodyne

Active Member
Nov 19, 2018
2,748
2,807
Los Angeles
Well, if I had one of these cars, and it failed just out of warranty, and I could prove by SMT or other method they had increased the max VPC, I'd be lawyering up...
 

aerodyne

Active Member
Nov 19, 2018
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Los Angeles
Yesterday, I AC charged from 48% to 50% and my fans/pumps ran the whole time. This has happened before and I posted here about it.

Since the time I got capped, I do not charge beyond 50% anymore.


Just checking, pardon if you have explained before.

My Pumps always come on when charging, but at a low level. Say 23-33%.

Then they shut off a few minutes after charging complete.

They never run at 100% unless I SuC or go past 78% SoC.
 

gmo43

Member
Jun 24, 2014
351
567
Mesa
Mine stop at 73ish percent.

I avoid having them come on in the first place by setting charge to 77%.

I am driving down further to make up for this capping, yesterday went to 23%, lowest ever.
Funny thing is i drive this car less because of such issue. So i Everytime I walk by it it's clicking/ticking and fans going. Like non stop. I was hoping last update would fix that but nope.

Car had been good to me besides Tesla theft. It's a shame.
 
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Droschke

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Mar 8, 2015
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Just checking, pardon if you have explained before.

My Pumps always come on when charging, but at a low level. Say 23-33%.

Then they shut off a few minutes after charging complete.

They never run at 100% unless I SuC or go past 78% SoC.

Yes, there is no common pattern. If not annoying, it's definitely not normal and not something the car used to do.
 

wk057

Senior Tinkerer
Feb 23, 2014
5,692
11,812
Hickory, NC, USA
Reviewed logs from over 100 vehicles with 85 packs on recent firmwares over the past several months.

Pumps run because the contactors are engaged because the DCDC is called for by the gateway because the 12V voltage is too low. There was a change to the firmware sometime in 2019 that "mitigated" the weak 12V issue (ie, making it less likely to need to be replaced despite being weaker than normally permitted) by lowering the 12V float voltage once 12V capacity got lower than normal, which limited the amount of time the car can sit with the DCDC disengaged. For the DCDC to be engaged, the battery loop pump has to run since the DCDC coolant is in parallel with the battery pack (lookup the diag screen thermal screenshots).

TL;DR - Pumps running have nothing to do with the HV battery range loss issue or any other safety issue and everything to do with Tesla not replacing 12V batteries as often.
 

aerodyne

Active Member
Nov 19, 2018
2,748
2,807
Los Angeles
Reviewed logs from over 100 vehicles with 85 packs on recent firmwares over the past several months.

Pumps run because the contactors are engaged because the DCDC is called for by the gateway because the 12V voltage is too low. There was a change to the firmware sometime in 2019 that "mitigated" the weak 12V issue (ie, making it less likely to need to be replaced despite being weaker than normally permitted) by lowering the 12V float voltage once 12V capacity got lower than normal, which limited the amount of time the car can sit with the DCDC disengaged. For the DCDC to be engaged, the battery loop pump has to run since the DCDC coolant is in parallel with the battery pack (lookup the diag screen thermal screenshots).

TL;DR - Pumps running have nothing to do with the HV battery range loss issue or any other safety issue and everything to do with Tesla not replacing 12V batteries as often.


Hard to understand why Tesla traded pump and contactors (My HV pack contactors replaced at 5yrs, 35k miles) wear and tear for prolonging the life of a $150 SLA batt which probably has to be replaced once during the warranty period.

Replaced my SLA after two years and it tested at 18Ah capacity. Contactors failed a month later.

One could keep the SLA batt on a shore charger, I have a hidden harness for that purpose. Or, perhaps replace the SLA before it has reduced capacity.
 

oaito

Member
Apr 27, 2017
58
105
Europe
Reviewed logs from over 100 vehicles with 85 packs on recent firmwares over the past several months.

Pumps run because the contactors are engaged because the DCDC is called for by the gateway because the 12V voltage is too low. There was a change to the firmware sometime in 2019 that "mitigated" the weak 12V issue (ie, making it less likely to need to be replaced despite being weaker than normally permitted) by lowering the 12V float voltage once 12V capacity got lower than normal, which limited the amount of time the car can sit with the DCDC disengaged. For the DCDC to be engaged, the battery loop pump has to run since the DCDC coolant is in parallel with the battery pack (lookup the diag screen thermal screenshots).

TL;DR - Pumps running have nothing to do with the HV battery range loss issue or any other safety issue and everything to do with Tesla not replacing 12V batteries as often.

While trying to follow your conclusion here... let me try a walkthrough if I got it right:

Example A - Or: Why the Wallbox will keep max range available.
- I am coming home and plug in my S85 into my Type2 11kW AC Wallbox, leaving and locking, the IC and CD going dark.
- While the charging commences, the 12V battery is drained until the next 12V charging cycle starts, hits the threshold and the 12V discharge/recharge cycle goes on.
- When charging the car overnight to e.g. 70%, 80%, 90% or even 100% is done, the car will still use the external AC to provide energy to run the cars systems so there is next to no HV battery drain despite the running systems.

Example B - Or: Why the UMC will not prevent HV draining.
- I am coming home and plug in my S85 into my UMC v1, then leaving and locking up, the IC and CD going dark.
- While the charging commences, the 12V battery is drained until the next 12V charging cycle starts, hits the threshold and the 12V cycle goes on.
- When charging the car overnight to e.g. 70%, 80%, 90% or even 100% is done, the car will stop using the external AC and start using DCDC to provide energy to run the car systems when the 12V battery voltage runs below a certain threshold thus coolant pumps are running and some HV drain.
- The amount of time used to charge to e.g. 100% is significantly longer, thus keeping the system active and discharging the 12V battery. A "worn out" 12V battery will not provide the same amount of energy/voltage thus resulting in longer 12V charging from DCDC thus leaving the coolant pumps running longer.


Countermeasures in order to reduce coolant pump activity while keeping range:

- Checking/replacing the 12V battery even if no warning is displayed should result in less 12V charging from the HV and less coolant pump activity.

- Use a Wallbox to lower the impact of recharging the 12V while coolant pumps are running, thus having max range available at the cost of some wear and energy usage from the grid/pv.

- Connect an external 12V charger which essentially keeps the 12V voltage high enough even at high SOC thus the GW will not request 12V charging from the HV and car can even go into Energy Saving Mode. This way you can leave the car unplugged and having next to no range loss "overnight". Or you charge with the UMC while having next to no range loss "overnight" after charging is done.

What do you think?

BR! Oaito.

PS: Well, seems to be a case of coincidence rather than correlation, perhaps I'm giving the engineers to much credit. On the other hand, their software solution to countermeasure and limit the "Condition Z" was called to be ingenious by yours truly, given that perhaps the "additional" coolant pump usage while charging 12V and discharging the HV is a hidden benefit?

PS2: A couple of years ago some smart guy took the liberty to explain way less smart guys like me how our brain is wired to see patterns and/or significance even when there is none - it is simply how our human brain is functioning after survival strategies were kind of engraved into our brain pathways. I recall he used some seemingly incredible "news" popping up during some Formula1 training session, whereas two drivers had lap times only milliseconds apart - the news was like: What are the odds! And the smart guy pointed out the odds to come so close was similar to any other variation +/- a couple of seconds. We just are wired to see a significance in the small difference, not because there actually was any. Which brings me to us owners, carefully and somewhat suspiciously looking into the behavior with every new f/w. Finding patterns and significance were there is simply coincidence. Thanks for sharing your findings!
 
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LaurS

Member
Oct 2, 2019
112
63
Camas, WA
Reviewed logs from over 100 vehicles with 85 packs on recent firmwares over the past several months.

Pumps run because the contactors are engaged because the DCDC is called for by the gateway because the 12V voltage is too low. There was a change to the firmware sometime in 2019 that "mitigated" the weak 12V issue (ie, making it less likely to need to be replaced despite being weaker than normally permitted) by lowering the 12V float voltage once 12V capacity got lower than normal, which limited the amount of time the car can sit with the DCDC disengaged. For the DCDC to be engaged, the battery loop pump has to run since the DCDC coolant is in parallel with the battery pack (lookup the diag screen thermal screenshots).

TL;DR - Pumps running have nothing to do with the HV battery range loss issue or any other safety issue and everything to do with Tesla not replacing 12V batteries as often.
Will a lithium 12V battery help reduce the pumps/contactors/DCDC usage?
 
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Droschke

Active Member
Mar 8, 2015
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A "worn out" 12V battery will not provide the same amount of energy/voltage thus resulting in longer 12V charging from DCDC thus leaving the coolant pumps running longer.

My 12v battery was replaced recently, so I don't consider it "worn out". The old 12v battery in the car for years (the worn out one) never caused this bizarre pump and fan behavior during and after charging sessions.

To the best of my recollection, this behavior started to show up around 2019.20 when the Chargegate was being noticed/reported. Prior to that there was no such a behavior and there were naturally lots of "worn out" 12v battery around.
 
Last edited:

aerodyne

Active Member
Nov 19, 2018
2,748
2,807
Los Angeles
Will a lithium 12V battery help reduce the pumps/contactors/DCDC usage?
In my opinion, no, and since the charging algorithm is not intended for lithium, may cause other effects.

The current preferred replacement DCS-33UNCR works well and when replaced, can be used for other things, like small solar, as I have done for the past year, or even thrown in the car as a back up to the installed 12v in case it should suddenly fail.
 

wk057

Senior Tinkerer
Feb 23, 2014
5,692
11,812
Hickory, NC, USA
This post has some fundamental misunderstandings.

While charging the HV battery, the contactors are closed, and the DCDC is enabled... so pumps must run. The 12V doesn't discharge while the HV contactors are enabled.

Charging via the charge port does not guarantee that AC power flows into the charger, and thus does not guarantee no drain on the HV pack.


My 12v battery was replaced recently, so I don't consider it "worn out". The old 12v battery in the car for years (the worn out one) never caused this bizarre pump and fan behavior during and after charging sessions.

To the best of my recollection, this behavior started to show up around 2019.20 when the Chargegate was being noticed/reported. Prior to that there was no such a behavior and there were naturally lots of "worn out" 12v battery around.

Like I said, changed sometime in 2019.

Unless the 12V battery is brand new, AND the gateway config has been updated to reflect that it's the most up-to-date variant of 12V that Tesla uses, then the car is going to protect the 12V from becoming weak and work to mitigate an already weak 12V by leaving the DCDC enabled for longer periods of time.

Only cars with a standby supply built into the HV battery (all Model X and Refresh Model S) get around this, since that small built in DCDC that keeps the MCU and BCM going doesn't require liquid cooling.
 

Droschke

Active Member
Mar 8, 2015
2,502
4,425
Future
Yesterday, I AC charged from 48% to 50% and my fans/pumps ran the whole time. This has happened before and I posted here about it.

Since the time I got capped, I do not charge beyond 50% anymore.

Still can't figure out why the fans that running loud during this ^^^ charging session I described. This was after a 6 miles round trip (3 miles downhill and 3 miles uphill) to a store, temp in 70's and then charging in a rather cool garage after coming back for only 2% !!!
 

wk057

Senior Tinkerer
Feb 23, 2014
5,692
11,812
Hickory, NC, USA
Still can't figure out why the fans that running loud during this ^^^ charging session I described. This was after a 6 miles round trip (3 miles downhill and 3 miles uphill) to a store, temp in 70's and then charging in a rather cool garage after coming back for only 2% !!!

This sounds more like a pump, fan, compressor, or active louver having an issue (real or miscommunicated) and forcing the system into a failsafe thermal mode (try to run everything at close to 100% and see if heat dissipates like it should).
 
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