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Charger instance NMEA2000

The WS500 sends NMEA data for Battery Instance 0, that's fine.

I already have this data from the Cerbo but ok.

Then the Charger instance as 49, and this is the data I find most interesting as this sends the alternator temperature.

They are both PGN 127508 but Raymarine instruments can only handle battery 1-5 (instance 0-4).

So my question is, how to change Charger Instance from 49 (battery 50) to for example 4 (battery 5).


Uploaded files:
  • instance.jpg


I am going to forward this one to Al at Wakespeed for followup.


ARG -- NMEA and details...

As you found, the WS500 is able to send 'NMEA2000' like messages via CAN, and uses 127508 as a way to send out some otherwise unavailable details for the alternator, specifically the alternator temperature.   When doing this we up-level the 'instance' number as a way to assure separation between actual batteries and the alternator -- hence the 49.  (This is also all contained in the WS500 Communications and Configuration guide, in the appendix of CAN messages).

As I understand, the issue is that Raymarine only allows 0..4 for this instance value...   I understand the NMEA spec calls for a range of 0..252, and also other folks using this message (not Raymarine) are able to receive it.  But Raymarine appears to be more restrictive.

I do not believe there are any other NMEA2000 messages which would allow for transmission of the Alternator temperature; though there are J1939 ones and of course RV-C has direct support, but that does not help in this case.


Perhaps you can contact Raymarine and inquire about their restricted range for the instance?  That would be the most complaint solution I would think..  Am a little hesitant to re-map the WS500 to a lower instance value, as that can introduce conflicts with other installs we have in place (ala, we have a few installs where there are 6x BMS's being aggregated, so they take instance 0..5  themselves).

Know this does not help fully, but maybe Raymarine has a more complaint update?



another idea:  using a CAN-CAN bridge, like the Yacht Dynamics device, one could write a translation script to receive the existing messages and re-map them to a lower instance for your specific install.  That could be another option.  Our comms guide has an example script that passes all messages CAN to CAN bridge passing NMEA2000, might be able to modify it to filter out this specific one and remap.




I hear what you are saying, but it would be nice to be able to control the charger instance yourself.

49 by default, or 0-4 if i want to.


Its not just the Raymarine MDF but also the I70S instruments.

Having the option to keep an eye on the alternator temperature from the helm makes sense.

Even Field 0-100% could be sent as an SOC data.


When WS500 communicates with Cerbo it creates other options, but we are not there yet.. (soon I hope?).

Having Raymarine create the option to read battery 50 just for me is probably not worth to spend time on.

Appreciate the feedback; at issue I think is the wide use of N2K and how it works on a wide range is displays.  Because some PGNs are reused for a lot of different sources (Battery, Alt, etc), we have taken this Instance Modifier approach - both int N2K and RV-C.


But it is a worthwhile topic to keep an eye on; if indeed it makes sense to take a different approach - we are all open to continued improvement!

Good luck getting Raymarine to mod their firmware with this feature in our lifetime.  ;-/

I have a similar set up: Raymarine, Victron, Wakespeed, Balmar.  So, another idea....   I ran a separate temp sensor from the alternator to my Cerbo. BTW, Cerbo temp inputs are compatible with LM335 so you can make your own temp sensors for less than a $1 (versus the $25+ for the one from VE). This is not a solution, but a fairly quick and easy work around.

-Mic (in beautiful Anacortes!)


Yes I have one temp sensor on each alternator to the Cerbo.

But I have not found an way to get the Cerbo to send this temp data over NMEA2000, have you?

Battery monitors, VE-BUS device and even MPPT sure.. but not these temp sensors.


TAR,   Well, that is disappointing. That was one of my motivations for installing the Cerbo.

No, I haven't gotten as far as trying to get temperatures and tank levels displayed at the helm, yet. I Just installed the Cerbo and temp sensor. If I figure something out I'll post here.

FYI, There is a NMEA PGN for arbitrary temperatures. Whether VE uses it or not...  dunno? I didn't see any way to set tank or temp instances in Cerbo's set up screens.

130312 - Temperature

"This is the currently recommended PGN for reporting arbitrary temperature. It uses the Instance/Source/Value schema to report multiple temperature sources and can report up to potentially 64009 different temperature readings (0-252 instances and 0-252 sources)."

Since so many MFD's can run apps, what would be very awesome would be to have a WS500 dashboard app that ran on the MFD. An app like the OGSS WS500 Configuration Tool/dashboard. Not so much to change settings but to monitor what is going on with the charging system. I find myself caring a lot more about it since having recently installed a LiFePO4 house battery bank and really want to monitor what the system is doing while under way.

Tank inputs works fine, I have 2 water tanks and one diesel.

I found an old tread on Victron Community about this but no answer:


It would be best if we could see the data the WS500 is sending as it would tell me what it sees.

There will always be some % difference between the Cerbo and the WS500.