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Timer charging restricted to 16A?

dan223

Member
Apr 29, 2019
356
145
Essex
Normally if its seeing a max of 16amps that is what the car sees the charge point advertising, if you stop it and then start it again from the app does it then show 32? Or does it require you to unplug and plug back in before it will then see 32?
 

HenryT

Member
Jan 29, 2020
554
444
Manchester
Normally if its seeing a max of 16amps that is what the car sees the charge point advertising, if you stop it and then start it again from the app does it then show 32? Or does it require you to unplug and plug back in before it will then see 32?

Only goes back to 32 if I remove/replace the plug. If I stop/resume the charge either via Tesla app or Wallbox app it resumes at 16A. Likewise, if I reduce the charge level below 16A and increase it again (via Wallbox app or on the car), it will only increase back to 16A.
 

WheresMyCar

Member
Oct 29, 2020
22
11
Horsham
I'm having a similar issue and, annoyingly, it only started after I started tinkering with the Scheduled Charge settings on the car screen. Had been charging perfectly at 32 amps (31-32 mph) before I started titting about with the settings after the latest update. My scheduled charge last night only ran at 5amps (hence why I'm working from home today). I cannot select anything above 16/16 amps on the screen even through my Rolec charger happily pumps out 32 amps when asked.
 

LongRanger

Active Member
Jan 11, 2020
1,317
1,198
Wales
You could try a scheduled charge using the supplied UMC running in Granny charge mode @ 13A for an hour or so, to make the car “learn” it now has 10A max from a 13A supply. Then go back to your normal charging config and see if the car “re-learns” its new theoretical max of 32.

When I’ve charged mine off my 16A charge point (Commando connector), and I switch back to my 32A commando location, the car only does 16A on scheduled charging unless I manually start it once at 32A, then reset back to scheduled - then it remembers 32 automatically for scheduled charging - however it always displays 16/16 until charging actually starts, even on the 32A connected setup.
 

HenryT

Member
Jan 29, 2020
554
444
Manchester
You could try a scheduled charge using the supplied UMC running in Granny charge mode @ 13A for an hour or so, to make the car “learn” it now has 10A max from a 13A supply. Then go back to your normal charging config and see if the car “re-learns” its new theoretical max of 32.

When I’ve charged mine off my 16A charge point (Commando connector), and I switch back to my 32A commando location, the car only does 16A on scheduled charging unless I manually start it once at 32A, then reset back to scheduled - then it remembers 32 automatically for scheduled charging - however it always displays 16/16 until charging actually starts, even on the 32A connected setup.


Thanks - I'll give that a go.

On your wider point, about the car 'learning' what charge rate to use, until this past few days I had never used timed charging as we were on a fixed tariff. I bought the car in January last year so its possible there is some history which could have caused it to default to 16A?

I have the car booked in for 2/2 so plenty of time to experiment, although I expect before then Tesla will cancel and tell me that a software update will cure this.
 

94jdh

Member
Sep 17, 2019
264
122
UK
Thanks - I'll give that a go.

On your wider point, about the car 'learning' what charge rate to use, until this past few days I had never used timed charging as we were on a fixed tariff. I bought the car in January last year so its possible there is some history which could have caused it to default to 16A?

I have the car booked in for 2/2 so plenty of time to experiment, although I expect before then Tesla will cancel and tell me that a software update will cure this.

I have the wallbox as well - my supply to the garage is limited to 30 amp ( old house) and found it would charge at this rate and back off to around 23/24 amps ( approx 5 kW/hour) - this was resolved for a while with a firmware update to the wallbox itself - have you the most up to date firmware on the the charger ( not the car)?
 

HenryT

Member
Jan 29, 2020
554
444
Manchester
I have the wallbox as well - my supply to the garage is limited to 30 amp ( old house) and found it would charge at this rate and back off to around 23/24 amps ( approx 5 kW/hour) - this was resolved for a while with a firmware update to the wallbox itself - have you the most up to date firmware on the the charger ( not the car)?

Not sure about the firmware so I will check.

That said, I had ruled out the Wallbox being at fault as a timed charge works fine at 32A on my wife's VW, with Wallbox managing the timing. Nothing else being changed, plugging my car in instead for a timed charge my car only draws 16A but the Wallbox software says 32A is being 'offered'?
 

Cnixon

Member
Mar 5, 2020
389
115
Basingstoke
Thanks, I thought about that but looking at the Tesla app it shows a good voltage, in fact as high as 244v, but typically around 239v so don't think that's behind the problem I have. Also, because if I just plug in without the timer being set, I get the full fat 32A straight away.
There is another 'post' within my link which is similar again. It really does look like its the cars onboard charger at fault.. the unplug and plug in is very odd. If you try setting the amps in the car to say 16A before you plug in can you increase the Amps. Or if possible set Wallcharger to 16A (Sorry did not realise it was a brand.) And increase it in smaller increments. Like said in the link the car has 2 16A AC chargers if one is playing up any amps above 16 would require the 2nd charger.
 

HenryT

Member
Jan 29, 2020
554
444
Manchester
Thanks for the further thoughts Cnixon.

I think it's really about the software controlling the charging and in particular about what happens when the car is asleep when the timed charging begins. If the car is awake, like when I pull the plug and reinsert it, then it will draw 32A. If the car is asleep and the charging starts automatically on a timed basis it only takes 16A and the Tesla app shows 16/16, i.e that it is drawing the maximum available. At that point the Wallbox app shows it believes it's delivering, or rather making available, 32A. If I try adjusting the amperage in the car after the timed charging has begun it won't let me go any higher than 16A, but it will let me go down lower. Going up again stops at 16A..

Adjusting the amps on the Wallbox app only has a 'visible effect' in the car/on the Tesla App to the extent the change is 16A or lower - move it above 16A and the car sticks at 16A, move it below 16A then the car/Tesla app shows the lower charge but again caps at 16 when the amps are increased, unless the plug is pulled/replaced.

I have had 'always connect' unticked in an effort to save on vampire drain, but have found my car then takes ages to wake up to connect to the app, or even to wake up when I get in it. It seems that it's getting into a deep sleep and doesn't want to play ball with the timed charges.

I have now re-enabled 'always connect' and will try again and see if that results in a lighter sleep and better charging outcome.
 

Cnixon

Member
Mar 5, 2020
389
115
Basingstoke
Thanks for the further thoughts Cnixon.

I think it's really about the software controlling the charging and in particular about what happens when the car is asleep when the timed charging begins. If the car is awake, like when I pull the plug and reinsert it, then it will draw 32A. If the car is asleep and the charging starts automatically on a timed basis it only takes 16A and the Tesla app shows 16/16, i.e that it is drawing the maximum available. At that point the Wallbox app shows it believes it's delivering, or rather making available, 32A. If I try adjusting the amperage in the car after the timed charging has begun it won't let me go any higher than 16A, but it will let me go down lower. Going up again stops at 16A..

Adjusting the amps on the Wallbox app only has a 'visible effect' in the car/on the Tesla App to the extent the change is 16A or lower - move it above 16A and the car sticks at 16A, move it below 16A then the car/Tesla app shows the lower charge but again caps at 16 when the amps are increased, unless the plug is pulled/replaced.

I have had 'always connect' unticked in an effort to save on vampire drain, but have found my car then takes ages to wake up to connect to the app, or even to wake up when I get in it. It seems that it's getting into a deep sleep and doesn't want to play ball with the timed charges.

I have now re-enabled 'always connect' and will try again and see if that results in a lighter sleep and better charging outcome.
Just to test turn on Sentry Mode from the app (Controls) that will keep car awake. Really surprised if this is because thev car is asleep.
 

26ct2143

Member
Nov 22, 2020
181
74
Burton-on-Trent, UK
Thanks for the further thoughts Cnixon.

I think it's really about the software controlling the charging and in particular about what happens when the car is asleep when the timed charging begins. If the car is awake, like when I pull the plug and reinsert it, then it will draw 32A. If the car is asleep and the charging starts automatically on a timed basis it only takes 16A and the Tesla app shows 16/16, i.e that it is drawing the maximum available. At that point the Wallbox app shows it believes it's delivering, or rather making available, 32A. If I try adjusting the amperage in the car after the timed charging has begun it won't let me go any higher than 16A, but it will let me go down lower. Going up again stops at 16A..

Adjusting the amps on the Wallbox app only has a 'visible effect' in the car/on the Tesla App to the extent the change is 16A or lower - move it above 16A and the car sticks at 16A, move it below 16A then the car/Tesla app shows the lower charge but again caps at 16 when the amps are increased, unless the plug is pulled/replaced.

I have had 'always connect' unticked in an effort to save on vampire drain, but have found my car then takes ages to wake up to connect to the app, or even to wake up when I get in it. It seems that it's getting into a deep sleep and doesn't want to play ball with the timed charges.

I have now re-enabled 'always connect' and will try again and see if that results in a lighter sleep and better charging outcome.
It's a strange one, because the AC-DC charger in the car is 3 phase, so it's default max is 16A/phase.
So it seems to default to the 16A 3 phase position on the car's screen.
The car does something different when on a 1 phase supply, allowing 32A draw on 1-ph.
It's almost like the car needs 2 settings in the software, a current setting for when on 1-ph and another for when on 3-ph.
 

Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,704
UK
It's a strange one, because the AC-DC charger in the car is 3 phase, so it's default max is 16A/phase.
So it seems to default to the 16A 3 phase position on the car's screen.
The car does something different when on a 1 phase supply, allowing 32A draw on 1-ph.
It's almost like the car needs 2 settings in the software, a current setting for when on 1-ph and another for when on 3-ph.

The three on-board chargers are all independent, rather than specifically three phase, with some front-end power switching that allows the connections from the chargers to the L1, L2 and L3 pins on the connector to be routed depending on the single phase charge current selected.

For anything between 16 A and 32 A the car connects two of the chargers to the L1 connector pin, for anything up to 16 A it only connects one charger to L1. I believe the capability is there to actually switch all three chargers to the L1 pin, giving up to 48 A from a single phase supply, but this doesn't seem to be an option that's enabled on UK/European spec cars AFAIK.

Apart from the cost saving that having three 16 A chargers on-board gives, there's also a small charging efficiency advantage. When charging at 16 A or less, the fixed losses in the charging circuit are just about halved, as only one charger will be active. This arrangement also means that the dynamic range over which each charger has to modulate (to comply with IEC 61851) is reduced, as the 6 A minimum is easier to achieve with just a single, smaller, charger in use.
 

arg

Supporting Member
Aug 22, 2012
1,803
1,787
Cambridge, UK
with some front-end power switching that allows the connections from the chargers to the L1, L2 and L3 pins on the connector to be routed

I think that's not true of @HenryT 's 2015 Model S - it certainly isn't of my 2014 model. I think the change came in with the facelift and the switch to the Model X charger (max 24A 3-phase), but I am not 100% sure and there might have been an intermediate variation.

Certainly early EU Model S had in effect 3 16A, single phase charging modules, or 6 of them if you ordered the 'dual charger' extra-cost option. The base model could charge from 32A single phase using the UMC, because the UMC blue commando adaptor bridged the three phase pins together; these cars could only charge at 16A from a standard 32A single-phase chargepoint. That was just about tolerable in mainland EU where domestic 3-phase is more common (and domestic high-current single phase rare), but in the UK with the OLEV scheme meaning that most people would have a free 32A chargepoint at home it was a significant problem. Just before launch in the UK, Tesla and Chargemaster flirted briefly with a plan involving Chargemaster units with the phases bridged, but it was rapidly realised this was a bad idea (such chargepoints blow up Renault Zoes for example), so the modified chargepoints were withdrawn and Tesla fitted all UK-delivered Model S with dual chargers whether you had ordered them or not. Somewhat later, a software kludge was implemented that stopped you charging faster than 16A on three-phase unless you had paid for the second charger.

So on this generation of Model S (unlike later Model S or Model 3 etc) there is no switching hardware to fail and result in a 16A limit. It is of course possible for the second charger to fail or for the software limiting kludge to have gone wrong. I wonder if Henry's car has the 2nd charger paid for.
 
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Reactions: Glan gluaisne

arg

Supporting Member
Aug 22, 2012
1,803
1,787
Cambridge, UK
I have been having a different problem since installing 2020.48.12.1 - though possibly related.

The car seems to charge normally for non-timed charging. However, if it wakes up for a timed charge it will sit there starting to charge, failing, and terminating the charge session (causing the contactor in the chargepoint to 'clunk' at about 2 second intervals). Having got into this state, manually stopping and starting the charge via the app doesn't help, but going outside and unplugging/replugging did. Last night, I just stopped it via the app to terminate the clunking and couldn't be bothered to go outside in the middle of the night; trying it again just now it still didn't work if I tried to start charging via the app (some 15 hours later), but did when I went out and unplugged/replugged. I then stopped it again and will see if it remains fixed tonight or if another timed wakeup gets it stuck again.

Obviously it could be some kind of fault with the EVSE/cables, but I have inspected the connectors and they look clean and in good condition, so it doesn't seem to be a case of a dirty contact being fixed by replugging.
 

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