We have two EVs sharing a single OpenEVSE charger — a VW ID Buzz and a 2019 VW eGolf. I’d like my home energy management system to know which car is currently plugged in,
since they have very different battery sizes and charging needs.
I understand the Type 2 pilot signal doesn’t carry any vehicle identity, so the EVSE itself can’t tell. But I’m wondering if anyone has found a practical workaround? Some
ideas I’ve been mulling over:
Charge curve fingerprinting — the two cars presumably draw differently enough that you could distinguish them from the current profile in the first few minutes. Has anyone
tried this?
Car OBD / onboard API — polling something in the car to see which one reports it’s charging. Both are VWs so presumably the same API (WeConnect?). Not sure how reliable or
timely this is.
Third-party services like eNode — these aggregate vehicle APIs and could presumably report which car is actively charging. Anyone using this?
Something physical — e.g. an NFC tag on each charging cable, or a BLE beacon in each car that’s detected when in range of the charger.
The use case is mostly for smarter scheduling and logging — knowing the ID Buzz needs a lot more energy than the eGolf, and being able to attribute charging costs to the right
vehicle.
Has anyone with multiple EVs found a simple way to do this? Interested in anything from quick hacks to proper solutions.
I think this would be tricky since the charge rate usually won’t start to curve unless SOC is higher than about 90%-95%, and the curve can vary depending on temperature etc. If the vehicle has an option to set a different charge rate this could be one way to differentiate.
This has been done, the OpenEVSE supports RFID with additional hardware. But since it involves adding hardware it will be more work than using the API IMO. I don’t think OpenEVSE sells a RFID kit, it will need to be DIY’ed using a PN532 board.
I’ve thought about the same 2 EV problem and have some ideas, but none explored very far. My Hyundai Ioniq5 charges at a different kW power level than my 2020 Chevy Bolt, so I can visually tell which car was charging from the charging rate graph after a few minutes. But the charging rates vary within a charging session, so I’m not how I would code a reliable automatic car detector from the power usage.
My 2024 Hyundai communicates its charging status to a website and a phone app, but both these Hyundai services require MFA to login so could be hard to program an automatic scraper. But I’ve signed up for Recurrentauto.com and when I provide it with my Hyundai account credentials, my dashboard shows charging status. Perhaps you could setup one of your cars with Recurrent and scrape charging status off Recurrent? Or see if VW provides an API that you could access?
My only other idea is to put physical switch next to the charger that I’d try to remember set whenever charging a car. The status of the switch could be read by a Pi or Arduino and transmitted to my emonPi. But I’m sure I would forget to flip the switch most of the time.
If there’s a difference in where vehicles get parked in order to access the EVSE, might there be scope to do image recognition from a CCTV camera covering the area? Maybe even ANPR or similar.
That wouldn’t help if it’s just a case of swapping the charge cable between two vehicles that always get parked in the same location, whether or not they’re charging; it’s probably asking too much to spot a cable or an open charge flap on a camera image…
To obtain an EV’s MAC address from a charge controller (EVSE) or its management system, the vehicle must be plugged in, allowing the charger to register the ID via OCPP (Open Charge Point Protocol) authorization messages. The MAC address is typically captured in the charging station’s database or backend system during the initial “unknown” authorization attempt.
Methods to Find the EV MAC Address
CPMS/Backend Logs: If you have access to the Charger Point Management System (CPMS) or backend database, check the “Authorize Request” logs when a car is plugged in.
Autocharge Feature: Some systems (e.g., Fastned, AMPECO) log the MAC address, often referred to in documentation as the EVCCID (Electric Vehicle Communication Controller ID), during the first session to enable AutoCharge.
Router/Network Logs: If the charge controller is connected via Wi-Fi/Ethernet, check connected devices in your home network router, though this might only show the charger’s own MAC address rather than the plugged-in car’s.
These methods are related to CCS charging. There is no MAC address in the standard J1772 (pilot) protocol. The J1772 protocol is elementary, just voltage level and duty cycle: Basics of SAE J1772 : Support
CCS charging uses PLC power line data transfer, which requires additional hardware, and is not used for traditional Level 2 (AC charging). With additional hardware, it may be possible to pretend to be a level 3 charger to read the MAC then drop to J1772 to start a Level 2 charge.
OpenEVSE does support OCPP, but Level 2 OCPP does not include the MAC
Homeassistant might give you a solution. It has native connection to OpenEVSE and can connect to VWcloud to get status of ID series cars. If system detects charging, it can detect which car status has changed to “charging”.