MQTT charger CAN protocol

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rfuegen asked Aug 24, '23

MQTT charger CAN protocol

my configuration:

3* Multiplus-II 48/3000

8* Tesla Model S battery packs 5.2kWh each 2s4p@48V

1* Cerbo GX

1* LogiBMS (Victron compatible)

3* EPEVER Tracer charge controller (60A / 60A / 100A)

an Arduino is already reading performance metrics (panel voltage, panel amps, temperature etc.) from the Tracers via Modbus/RS485.

I now want to feed those metrics to the Cerbo via VE.CAN, but can't find the specification on how the Victron MPPT charge controller communicate on the CAN bus.

I aldready checked the "VE.Can-registers-public.pdf", but it doesn't seem to contain MPPT specs.

please advise. thanks.

MPPT Controllers VE.Can

2 |3000

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bathnm answered · Aug 24, 2023 at 06:46 PM

@rfuegen Its not simple. You ill need to build a CAN bus stack that will broadcast a mix of CAN and VE.Can messages and listen for VE.CAN messages. The CAN communication is very complex and you would need to handle all the address management messages, device identification messages before you even think about the data to be sent. As you have also found a lot of the data is sent via VE.Can and therefore you would have to do a lot of reverse engineering.

It would be fare easier to purchase some Victron MPPTs and hook them up via VE.Direct.

If you really want to do this, find yourself a good N2K/CAN library (google searching will turn some up) to get the device visible and then expand that to handle any messages that you find are needed.

2 |3000

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Modifications Space

Node Red Space

Answer 1 · 2023-08-25T01:21:00Z

rfuegen answered · Aug 25, 2023 at 01:21 AM

@Bathnm thanks for the answer, although it is a bit discouraging.

I had a look at the source code of TeslaBMS/LogiBMS, where the CAN part is pretty simple. Hoped that MPPT comms would be similar.

purchasing Victron MPPTs would be an option if there's only a single "small" charger to replace, but replacing three "big ones" is not covered by my budget.

anyway, thanks for the hint, I'll look into the N2K/CAN libraries.

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Answer 2 · 2023-08-28T15:27:29Z

rfuegen answered · Aug 28, 2023 at 03:27 PM

After some consideration, I think I'll go with VE.Direct interface. collect metrics from all three Tracers into a single record, pretend to be a MPPT VE.Can 250/100 on the VE.Direct side.

all three Tracers combined have a total nominal charge current of 220 amps. will there be a problem if I identify as MPPT 250/100, but report more than 100 Amps?

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Answer 3 · 2023-09-04T09:25:36Z

Jason - UK answered · Sep 04, 2023 at 09:25 AM

@rfuegen you know those Tesla battery packs are 22.2v nominal, therefore in series they are 44.4v nominal, not 48v? Just noting your original post about your set up having '8* Tesla Model S battery packs 5.2kWh each 2s4p@48V'.

2 |3000

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