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Smart EQ ForFour
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Discussion Starter · #1 ·
Over in the General Mercedes EV section @RedSmartEQ and I are discussing the fact that his/her Sync EV charge point sends 15-second 6A charge pulses every four minutes while a scheduled charge is pending to ensure the car doesn't enter "sleep" mode and therefore fail to wake for the scheduled charge. This naturally causes the car's relays to clunk on and off every four minutes, and causes the car to send an alert to its app that charging has started every four minutes. To say the least, this seems clearly to be a very "brute force" method to ensure the car doesn't sleep through its scheduled charge.

I am awaiting installation of a Sync EV and I have essentially the same car as @RedSmartEQ, so this naturally concerns me. I do not want the HV relays on my car cycling 15 times an hour instead of twice a day, especially not in the night right outside my sleeping daughter's bedroom window.

I contacted Sync EV who told me that the "pulses" are the only way to ensure a car doesn't fail to wake for its scheduled charge, and that all manufacturers use the same method (unless they have access to the car's API). They said that the pulses could be disabled, but if you did this they could not guarantee the car would wake.

Sceptical, I contacted Ohme (whom I know has very responsive customer service even for technical questions, and has previously told me that they have not had any problems with my particular car waking from sleep to accept a charge even though there is no API access). Ohme told me that they do not use pulses - rather, they simply send a signal on CP when the car is plugged in so that it is ready to accept the charge, but no charge actually passes through until the scheduled time. When the scheduled time arrives, this changes to provide a charge.

I have similar queries pending with EO and Wallbox but have not heard back yet. I've also asked Mercedes Benz whether these pulses should be necessary, but as is typical they've successfully dodged or misunderstood my question three times in a row now.

So - I would be interested to hear from other charge-point manufacturers (e.g. @Mike Schooling, @Flavian Alexandru) and technical experts on this forum:
1. Are these "pulses" an industry-standard way to ensure EVs are awake to accept a scheduled charge?
2. What other methods are used (e.g. Ohme's method) - and is there a material reliability difference?
3. Is it likely that Sync EV's method is a "belt and braces" approach and that asking them to switch off the pulses would end up being the same as Ohme's method? (I've asked Sync EV this but have not heard back yet.)
4. Surely this issue was considered when the communications standard was developed - what method does the standard anticipate?

I would also be keen to hear from other Sync EV owners who use it to schedule charges (e.g. @Jedispooner) and whether they have the same behaviour from their units.

Thanks!
Ben
 

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Just to add my quick observation. I have a script that changes the zappi mode from fast to eco+ (which in my case as I don't have solar means off) and vica versa to schedule the charge. I noticed that my Tesla M3 wasn't always charging properly and it's because if there's a big gap between charges the car goes to sleep and then doesn't wake up to take the charge, so in my case I wake the car up via the API and it works fine. This comment probably hasn't helped much, but just acknowledging that I've seen this issue!
 

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Tesla Model 3's had this problem, essentially they were non-compliant with IEC61851. The problem was that the car would not wake from a deep sleep when the charge point started advertising the available current, inviting the charger to request power. Tesla fixed it with a software update around June 2020, after a great deal of pestering. I kept submitting service requests for every failed timed charge, pointing out that their compliance statement with the car documentation was falsified, and that the car was non-compliant. I did get a phone call immediately after the software update that fixed it, though. They didn't fully admit to the failure to comply with the standard, but they did ask me to check to see if the problem was now resolved (it was).

I suggest doing the same with Mercedes. Failure to comply with a certification standard is the point to make, as I doubt they want to fall foul of such a problem.

The way the charging system should work, as defined in IEC61851, is that this sequence should be followed, for a timed charge under the control of the charge point:

  • Before the car is plugged in, the Control Pilot (CP) should be in State A, a steady +12 VDC, with a source impedance of 1 k ohms
  • When the car is plugged in, the charger should load the CP down to +9 VDC, to indicate that a connection has been made.
  • The charge point detects this loading and if it is not ready to supply power (because it's on a timed schedule), it should hold the DC signal on the CP
  • The charger should recognise that the charge point is ready, and in standy, and should wait indefinitely for the charge point to signal that power is available.
  • When the scheduled charge time is reached, the charge point should start to advertise the available current to the charger, by putting a 1 kHz pulse train on the CP
  • The charger measures the duty cycle of this pulse train, sets its current limit to not exceed the advertised current and then load the positive going part of the CP signal down to +6 V
  • The charge point detects that the charger is requesting power, from the loading, and if no fault is detected it turns on the contactor to supply power down the charging lead to the charger
  • If the charge point timer turns off the charge, then the charge point switches off the 1 kHz CP signal (but not the mains power at this stage).
  • The charger detects the loss of the 1 kHz CP, and turns off itself off, so it isn't drawing current, and then unloads the CP so it returns to +9 VDC
  • The charge point detects that the CP has been unloaded and opens the contactor to remove mains voltage from the cable.
  • The charge point and the charger then stay in the standby state indefinitely, with the charger waiting to see if the charge point starts to advertise that power is once again available
 

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Discussion Starter · #4 · (Edited)
Thanks Jeremy - that's incredibly helpful to finally see how this is all supposed to work. Sometimes it seems that consumer-facing documentation is so dumbed down it becomes useless.

I suggest doing the same with Mercedes. Failure to comply with a certification standard is the point to make, as I doubt they want to fall foul of such a problem.
To be clear, there is no indication that Smart (or other MB cars) fail to wake or are otherwise non-compliant - in fact Ohme has told me they've never had a problem with them.

The issue is with Sync EV's implementation - I don't want the pulses if they're not necessary, and this is making me consider cancelling my order and selecting one that doesn't do this. I appreciate that they've said the pulses can be disabled, but the fact that they have them on by default makes me concerned that they are not confident in how their systems work.

The reason this is important to @RedSmartEQ and me is that Smarts do not allow you to set a maximum charge and thus will always charge to full - so we are reliant on external charge points to schedule to preserve battery health.
 

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EO don't do this.

It seems to be a problem only with early Tesla Model 3's that, like someone else has already said, was a non-compliance that's now fixed.

EO's way of getting around this was to advise Model 3 owners to use Sentry Mode to keep the car awake. Seems absolutely absurd to pretend to start a charge 15 times an hour as a workaround to a problem that doesn't even exist anymore, and only ever existed for one model of car!
 

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TBH, the only reason I can see for pulsing power on and off from the charge point is to get around a non-compliance with IEC61851. The charger (in the car) should always be ready to respond to a change of state on the CP of the charge point when the car is plugged in. Going to sleep should have no impact on this.

The app wake up is unrelated to this, and seems to be something else entirely, most probably associated with the comms link going down when the car is asleep. Tesla's do this, they turn off WiFi when asleep, and will only wake up when they receive an SMS via LTE, or when the car is unlocked.
 

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42k miles on public charging. Am I an expert yet?
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TBH, the only reason I can see for pulsing power on and off from the charge point is to get around a non-compliance with IEC61851. The charger (in the car) should always be ready to respond to a change of state on the CP of the charge point when the car is plugged in. Going to sleep should have no impact on this.

The app wake up is unrelated to this, and seems to be something else entirely, most probably associated with the comms link going down when the car is asleep. Tesla's do this, they turn off WiFi when asleep, and will only wake up when they receive an SMS via LTE, or when the car is unlocked.
It would make sense if the car and app are set up to send a notification every time the car thinks a charge is starting? No idea why you'd want that but it's basically the same as the Charge Finish notification I get from the Nissan app...
 

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Discussion Starter · #8 ·
It would make sense if the car and app are set up to send a notification every time the car thinks a charge is starting? No idea why you'd want that but it's basically the same as the Charge Finish notification I get from the Nissan app...
This is what Smart's app does by default but it can be turned off. The notifications aren't an issue - just an annoyance - and seem to be working as designed if, indeed, the charge point is allowing the car's charger to start a charge every four minutes.
 

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For the record, For my Tesla M3P (bought Sep 2020), I set my SyncEV into basic mode (so it effectively is ready to send charge immediately) and I set the start time and target charge % in my Tesla. I also have a Tesla charger and that works in exactly the same way as the SyncEV in basic mode.
 
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