[FAQ] - EV Chargers - common misconceptions - what is an EVSE?

[daveo4EV]

Over the years new EV owners inevitably end up with a series of questions - this FAQ is an attempt to demystify the EV Charger (EVSE)

this FAQ will lean heavily on my personal experience/knowledge of North American EV chargers - much of this applies in the rest of the world, but if you're not North American you may want to recheck my assertions for your particular region…

Summary/TLDR; an EVSE is a power cord attached to a safety switch - nothing more - nothing less…(thanks to tooney from the Taycan forums for this pithy summary)

read on for a more detailed break down!

• 1st off what people think of as an EV charger is _NOT_ in fact a charger at all. The EV charger included with your Macan/Taycan is technically an EVSE (Electric Vehicle Supply Equipment)device. It _DOES NOT_ charge your battery - it is simply a raw-external power supply (120V or 240V AC power supplied by your home/electrical grid).
  • The actual EV charger is an AC power to DC power converter "box" embedded in the vehicle. This box receives "raw AC power" from the EVSE - and converts it to DC power suitable for charging the battery - it's run by thousands of lines of software that control the power flowing into the battery and manages the charging process to Porsche's exact specifications.
  • The EVSE is frankly dumb as a rock in this design and sits "outside" the vehicle simply waiting to be told to "let power flow" - that's _ALL_ it does! It does NOTHING MORE than that!!
    • car says: "please may I have some power?"
    • EVSE says: "ok here ya go"
    • car says: "power stop now"
    • EVSE says: "ok power stopped"
• What does an EVSE do?
  • EVSE's are normally installed on a dedicated 240V residential circuit - ranging in AMPs from 20-100 amps. This yields a charging capacity of 4.8 kW to 19.2 kW of raw AC power depending on the wire gauge and circuit breaker size. An EVSE does a few simple things:
    • it's primary function is as an on/off safety switch - power flow control for safety
      • no power is flowing in the EV charging cord if it's not plugged into the vehicle - this is an EVSE _MAIN_ feature/function - if we didn't have this you could just use an Extension cord - but an extension cord is "always powered" and would electrocute you if it was raining and you dropped it in a puddle
    • the power flow control is controlled by the car - the onboard charger and associated software inside the vehicle "tells" the EVSE to allow power to flow or not-flow - so it's an on/off switch - but is 100% controlled by the onboard vehicle charging software
      • conceptually the EVSE can not "initiate" a charging session - the car _MUST_ request the power be allowed to flow by the EVSE
      • the EVSE is NOT Pushing power into the battery - the car is "pulling" power from the EVSE
      • the EVSE can NOT charge your car or start a charging session - only the car can allow the battery to charge - and the EVSE passively waits for the car to "request" power
    • the EVSE informs the vehicle as to it's configured capacity. The EVSE advertises its AMP capacity to the EV via a standard EV charging protocol. This capacity advertisement allows the EV to adjust its charging demand to avoid exceeding the EVSE's advertised capacity.
      • the car and the EVSE always "negotiate" teh charging rate. Your EV has a "max" AC charging rate (Macan is 9.6 kw in North America).
        • if you plug into a 3.6 kW EVSE - your Macan will only charge at 3.6 kW
        • if you plug into a 19.2 kW EVSE - your Macan will charge at it's "max" rate of 9.6 kW
      • the current capacity of a given EVSE can change dynamically during a charging session - this is supported by the charging protocol - so depending on circumstances your charge rate may not be constant for any given charging session if the EVSE is "adjust" power demands in real time
        • for example a 'solar-tied' EVSE may ramp it's max capacity up/down to "match" current solar production to avoid using more power than Solar is providing - well behaved EV's are expected to respect these adjustments and adapt in real time as the EVSE adjusts it's advertised maximium
• North American EVSE's (including the Porsche one) all conform to the SAE J-1772 EV charging standard.
  • all North American EV's support J-1772 EVSE's
  • this means _ANY_ J-1772 compliant EVSE can charge your Macan - it has to work that way!!
    • this is what allows you to use public chargers at the mall - they are all J-1772 EVSE's
  • Any J-1772 EVSE can charge any J-1772 EV
  • J-1772 EVSE's are not vendor/vehicle specific
  • even Tesla's home EVSE's are J-1772 EVSE's but have a non-J-1772 shaped connector/plug - but the protocol/standard is J-1772 - which is how/why a Tesla EVSE can charge your Macan
• EVSE's are more like a water-valve than water-filter. They are simply an 'on/off' safety device. They do not filter/manipulate the AC power that is flowing through them. This means that your EVSE does not change the power it's delivering to your car. It's the same "raw" AC power that is being fed to your home from your grid supplier.
• EVSE's are very similar to glorified GFI outlets - while they do not manipulate/change the power flow (or quality or characteristics) they do monitor the charging process for electrical faults. Their main "weapon" in the fact of electrical faults is to simply shut down and turn off the power flow.
  • AN EVSE may fail to charge an eV because the electrical circuit has an AC electrical problem or the car has an AC electrical problem. In the case of the EVSE detecting a fault with the AC circuit - it should simply fault to "no power flowing" and may or may not display a "fault" indicator.
• Power is only allowed to flow when the charging cord it actually connected to an EV - this is the EVSE's main function - it's for safety
• EVSE does not control "charging" your car - your car controls charging your car - it simply asks the external EVSE to turn of or off - opening and closing the circuit to allow power to flow
• The J-1772 protocol/standard isn't very smart. It was designed to be simple, easy and not very challenging for anyone to implement. Therefore there is very very limited "control" an EVSE can exert over your EV. Any "scheduling" an EVSE can do is therefore limited to what the J-1772 protocol/standard allows. which is not very much.
  • Primarily you're going to control your EV charging with what ever software/features your EV provides for charging - the EVSE not the brain or controller of the charging process - your EV controls everything.
• Some EVSE provide additional features - these features are beyond the J-1772 standard and have nothing to do with charging
  • scheduling
  • statistics
  • status
  • start/stop
  • sometimes these features will conflict with the car and confuse the car's on board charging hardware/software - leading to missed charging sessions or incomplete charging sessions
  • Author Opinion: the dumber/simpler EVSE's are the best EVSE's because they are the least likely to "argue" with the car about charging.
    • Enphase/Clippercreek make some of the dumbest EVSE's on the market - and because of that their compatibility and reliability is simple stellar - they "just work" and have an excellent reputation for quality and robustness.
• In North American "mobile" EVSE's are limited to 9.6 kW max charge rate - these are plug based EVSE's and normally small enough to unplug and take with you on a road trip. The maximum charge rate is limited by the maximum plug capacity in North America - which is NEMA 14-50/6-50 outlets - 50 amp outlets which provide a maximum power output of 9.6 kW
• Wallmounted or non-Mobile EVSE's (hardwired) can provide up to 19.2 kW of charging capacity - this is 100 amp breaker on a 240V circuit. Most residential homes in North America lack sufficient capacity for this level of EVSE. EVSE's on 60 amp or greater circuit size MUST be hardwired and can not be plug based due to building code regulations - this makes them "non-mobile".
  • but they are still a glorified on/off switch and simply provide "raw AC" power to the onboard charger in your Macan.
• Any standard compliant EVSE can charge any EV - there is _NO_ expectation of vendor specific EVSE's for certain EV's - this violates the J-1772 standard and would mean you could not use commercial public charging infrastructure when away from home.
  • if a given EVSE can not charge an EV there is either a bug/fault on the EVSE or EV - one of the two sides should "fix" the problem
  • there is no reason what so ever that an EV can not charge from any EVSE…
• J-1772 is the "basic" standard for North American EV charging - some EV's and some EVSE's implement standards beyond J-1772. Primarily these standards provide more "status information" back to the EVSE so it can display things like: battery %, estimated charge completion time, charging start time. I would characterize these enhancements as largely "status" related - but do not change the nature of raw AC power flowing to the vehicle. The J-1772 protocol lacks these basic status meta-data so some EVSE's and EV's have added features to their EV/eVSE to provide this charging meta-data
  • however all EV's and EVSE's must provide basic J-1772 support - so that when encounter an EVSE or EV that only supports basic J-1772 - both will interoperate
• NACS is a new plug shape/type - but still a J-1772 electrical protocol and service. Even when using a NACS EVSE your Macan is still working with the J-1772 EV charging standard - but is no longer using the physical J-1772 plug…
  • this is why adapters are no big deal.
• J-1772 is an AC charging standard - CCS(1 or 2) is the standard/protocol for DC fast charging and covers delivering raw DC power from 20-500 kW and voltages of 100-1000V volts - it's an entirely different animal but similar in nature to it being a reasonably "stupid/simple" protocol.
  • more can be learned here…https://driivz.com/blog/ev-charging-standards-and-protocols/
• there are protocols in other parts of the world for EV charging that while not exactly J-1772 are very very similar - these are ISO-xxxx protocol standards for EV charging. Most EV's shipping world wide have universal onboard EV chargers and the software for them knows how to speak all the EV charging protocols - and simply adapt to what ever protocol is required when they are plugged into an EVSE. Even though European Macan's use an ISO protocol for AC charging in Europe - I know for a fact unmodified euro-macaw's worked flawlessly in North America when euro-models were being tested in North America…
  • the cars are shipped from the factory with regional specific charging ports - but the onboard chargers and their software are "native world wide" and can handle anything…
• unlike $200 toys, or cell phone chargers, or notebook chargers - just because your EV is plugged into an EVSE does not mean it's "charging" - there is NO power following unless the car allows it - and most (all?) EV's I'm aware of do not continuously "draw" power from an EVSE
  • charging an eV from an EVSE is very much an on/off affair - there is no "trickle" charging or over charging of an EV battery just because you've left it plugged in.
  • therefore unlike your cellphone, toy, or laptop you're not continuously "pushing" electrons into the EV's battery - because the car does not operate that way.
    • The onboard charging hardware and software has a record of all the KWh's that have been input to the battery and output from teh battery. They constantly balance these two numbers - and only push power into the battery when they detect an outflow which they then balance with an inflow should power be available.
  • you can leave a car plugged in for weeks to an EVSE - and the EVSE may never actually charge the car because the car does not wake up and request power from the EVSE…
  • the EVSE does not charge your battery/car. The car charges itself using power from the external EVSE should power be available. The EVSE is a largely passive device - again like a water valve - that the car turns on and off.
• What is L1/L2/L3
  • these are legacy terms that have been used imprecisely over the years - but in early days would used to distinguish slower EVSE's from faster EVSE's
  • L1 routinely maps to 120V EV charging and normally tops out at 30 amps or about 3.6 kW - although 1.44 kW to 2 kW is the 95% most common L1 charging rates
  • L2 routinely maps to 240V EV charging - and histrorically ranged from 3.6 kW to 9.6 kW - and in about 2012 started encompassing 11 to 19.2 kW charge rates
  • L3 was anything more than L2, and has been imprecisely used for both AC and DC charging - and has no common usage or expectations beyond it's faster than L2…but how much faster and if it's even AC or DC power is all over the map…
• In terms of "power quality" one EVSE is not better than another EVSE - it's can't be. All EVSE's are simply "pass through" devices for what ever "raw" AC power they are being fed by your home/electrical grid connection. If something damages your battery it was not the EVSE - it was an AC power fault that happened on/in your home's electrical wiring or most likely was problem with the power being supplied "from the grid"…again think water valve vs. water filter…
  • an EVSE is simply a switch (on/off) not a filter/regulator.

that's all for now - I'll update this post/thread as I remember additional "facts" - but the items above should go a long ways toward demystifying what an EVSE actually is and what it can and can not do.

Questions are welcome! I'll do my best to answer them and so will other's on the forum.

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[daveo4EV]

Porsche EVSE - not a charger - it's an ISO charger that supports J-1772 - so it can/should be able to charge any North American J-1772 EV…even a Tesla with an adapter.

because it's mobile in North America - max power is 9.6 kW - depending on powersuplpy cables (optional $200 items) it can vary in power from 1.44 kW, 5.67 kW, or 9.6 kW - and can be configured to run at 1/2 capacity which is 0.77 kW, 2.8 kW, or 4.8 kW…

https://www.suncoastparts.com/produ...XFDpzV4rvRtc1HYefQROiJxs8x4uSfdRoCGqMQAvD_BwE

 

[daveo4EV]

Porsche Wall Charger - still an EVSE - just walled mounted - adjustable charge rate to "match" circuit breaker size - 3.6 kw to 19.2 kW supported - still a J-1772 EVSE - still mostly dumb as a post - still "simple" but has some ISO support for the Taycan so it can show battery percentage and charging progress - strangely enough Macan does not support the same ISO meta-data that the Tacan does - {sigh}

https://shop.porsche.com/us/en-US/p/porsche-wall-charger-connect-9J1068209-B/9J1068209

 

[daveo4EV]

here is a brief history of the Prosche/Audi EVSE's - it's not a quality product and remains problematic
https://www.taycanforum.com/forum/t...uide-to-the-porsche-evse-pmc-pmcc-pwcc.13886/

if using a non-porsche EVSE would cause problems then why did Porsche add support for 1000's of nation wide ChargePoint chargers (non of which are porsche EVSE's)
https://www.macanevowners.com/forum...t-integration-to-myporsche-app-gain-me.20947/

this link is guidance for new owners about installing a home charger and which one to choose
https://www.macanevowners.com/forum...owner-what-home-charger-evse-do-i-want.18162/

Adapters are not that complex, they are infact "passive" electronic devices and are simply mapping one wire connector to another wire connector, but can not and do not "change" anything other than the physical shape of the connector…
https://www.macanevowners.com/forum...es-the-tesla-tap-work-with-my-macan-ev.18010/

 

[daveo4EV]

this _IS_ the charger for your Macan/Taycan/Cayenne eHybrid/Panamera eHybrid/Audi Q6

this is the actual device/hardware that charges your battery - it's installed at the factory - and it takes raw AC power in one side - and spits out raw DC power on the other side - your battery can only be charged by DC power (there is no such thing as an AC battery)…

Porsche has mounds and mounds of software in the car to control this thing and it "speaks" J-1772 (and ISO protocols) to external EVSEs

Taycan has an optional "upgrade" package where you can replace the factory default 11 kW model with a 19.2 kW model for fast maximum charge rate. When I investigated it years and years ago it was about $1900 in parts/kit + labor - bringing it to a $5k-$6k upgrade cost to modify my 2020 Taycan from the standard 11 kW OBC to the enhanced 19.2 kW OBC (onboard charger)

the main reason I was considering this, was the 2020 Taycan's did not support plug&charge - and the necessary P&C certificates could not be provisioned on a 2020 Taycan -but if you upgraded the OBC from the 11 kW version to the 19.2 kW version. you also got P&C along with the deal…

I considered it and then remembered $5k is a lot of money and I didn't use P&C that much and EA didn't operate that well - so it would not be money well spent.

https://www.taycanforum.com/forum/t...ng-retrofit-cost-in-us-price-breakdown.12325/

there is a box like this somewhere inside _EVERY_ EV and it is the real charger - not the external EVSE that we all think of as a charger.

 

[Dragon Tourniquet]

Very nice faq. Minor nit, but CHAdeMO doesn't use J-1772 for signaling (direct CAN bus communication? Seems nuts to me) and there are still Leaf's around that use it (and even a few public chargers too, but they are going away).

 

[daveo4EV]

Very nice faq. Minor nit, but CHAdeMO doesn't use J-1772 for signaling (direct CAN bus communication? Seems nuts to me) and there are still Leaf's around that use it (and even a few public chargers too, but they are going away).

yeah probably - Chademo is a dying standard - and only for DC fast charging - even the Nissan Leaf uses J-1772 for AC charging and was a 3.6 kW or 7.2 kW EV…

https://en.wikipedia.org/wiki/CHAdeMO

 

[fsabek]

Thank you for the thorough explanation I felt your post came as reply to my charging post that posted yesterday

 

[Paris92]

Excellent post. Many thanks.

 

[daveo4EV]

Thank you for the thorough explanation I felt your post came as reply to my charging post that posted yesterday

I've been "thinking" about this post for years - finally got around to authoring it - the points/facts are nothing new and many many EV owners don't understand what an EVSE actually does.

 

[daveo4EV]

terms of "power quality" one EVSE is not better than another EVSE - it's can't be. All EVSE's are simply "pass through" devices for what ever "raw" AC power they are being fed by your home/electrical grid connection. If something damages your battery it was not the EVSE - it was an AC power fault that happened on/in your home's electrical wiring or most likely was problem with the power being supplied "from the grid"…again think water valve vs. water filter…

• an EVSE is simply a switch (on/off) not a filter/regulator.

if you think about it - it's very very very unlikely anything happening from the EVSE to the OBC (onboard charger) would damage the battery - the OBC is effectively a "firewall" electronically - AC power faults might damage the OBC - but it would be a very very complex and unlikely scenario that AC power flowing into the OBC is then successfully converted to DC power and then allowed to actually damage the LiON cells - the OBC is both a firewall and circuit breaker of sorts and would "absorb" any electrical energy and sacrifice itself before AC power would be successfully passed as DC power onto the battery…

the AC power simply has no way to "get past" the OBC to impact the battery…this is one of the reasons why "you" can't do anything to the battery - you as the owner are simply plugging in an external aC power supply - but the car's own software+hardware is what actually controls the DC charging process - you couldn't damage the battery if you tried with an external AC charger - and the OBC should be robust enough to simply absorb any "bad energy or faults" - it might fry and fail - but it's highly unlikely it allows any DC power beyond itself when it's being damaged.

my $0.02

 

[Goldtrom]

I’m a EE and this all still sounds like an unnecessary pedantic rant. I have no issue with non tech people calling an EVSE a charger. It’s a required part of the home charging system. I still call usb c cables charging cables because that’s all I use them for. Who cares that it’s basically just two wires.

 

[CandianPorsche83]

I’m a EE and this all still sounds like an unnecessary pedantic rant. I have no issue with non tech people calling an EVSE a charger. It’s a required part of the home charging system. I still call usb c cables charging cables because that’s all I use them for. Who cares that it’s basically just two wires.

Useful and a great read for a joe blow like me … not an EE

 

[Goldtrom]

it can be useful without having a condescending tone. All the unnecessary parts about a EVSE being not a charger come across as condescending.

English is a fluid language. The EVSE has become known as a charger by the general public. The whole an EVSE is not a charger crowd have lost.

And my EVSE is able to schedule times and monitor energy usage on top of all the “dumb” things it does. Sure the vehicle has to agree to accept the charge but it’s negotiated. The car doesn’t get the only say in the matter.

That makes it more than just a safety device.

 

[vanjwilson]

I bought a used Gen1 Tesla Mobile Connection (max power of 40amps) to leave plugged into my NEMA 14-50 plug in my garage to use as my "home" charger short after I got a Model Y in 2021. This allowed me to leave the Gen2 Mobile Connector (max 32amps) in the car for use in emergencies on the road.

I included the Gen2 Mobile Connector when I traded in the Model Y for my Macan, and kept the Gen1. I ordered a Tesla-plug-to-J-1772 port adapter (Lectron brand) so that I can keep using the Tesla as my home charger. (The adapter also comes in handy on road trips for using Tesla Destination Chargers (Level 2), like some hotels have.

Related: I do miss the way the Tesla would show you the voltage and amperage of your charge, not just the kW. I don't miss it enough to invest in an OBD2 scanner, though.

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