Zeus as REC Active follower on 500k bms can but no cerbo widget.

Trond

4/7/25, 12:59 AM

There is already another thread on this subject.

Interesting that you got the Zeus to follow the REC A-BMS using 500 kbps.

Are you seeing the Zeus confirming that it IS synced to the A-BMS?

NMEA2000 is 250 kbps, so I can not apprehend how it should sync to A-BMS and Cerbo at 500 kbps, and send NMEA2000 at 250 kbps at the same time, its simply not possible.

Besides, its supposed to work with Victron DVCC and Lynx Smart BMS NG, all works on VE.CAN using 250 kbps.

Matt

4/7/25, 5:56 AM

Trond

yes, I've got VE.Can port 2 configured for 500k LV BMS with the REC-A plugged into one of the ports, the other port has the Zeus connected with a 25' cat6 network cable and a terminator in the N2K micro-c connector on the Zeus. The Zeus is set to REC follower, reports that it is following the REC, and does display legitimate battery voltage/current etc....

prior to this I had tried using the Zeus as a Victron follower on CAN 1 at 250k. I was able to see the Zeus as a widget on the cerbo, I could see engine and alternator speed, and alt watts. But the Zeus wasn't receiving any information about battery current/voltage, It was pulling battery voltage from the positive lead nearest the alternator. So not at all correct. In this configuration I didn't see anything that would lead me to believe that the Zeus was following dvcc.

Matt

4/7/25, 5:58 AM

I was told by ARCO that setting the Zeus to rec follower changed its comm rate to 500k.

I briefly tried changing the REC to 250k but the cerbo didn't immediately recognize it. Admittedly I didn't invest much time into this experiment.

Trond

4/7/25, 6:14 AM

Yes, I am seeing the same thing.

REC->Zeus works at 500 kbps. (Sync enabled and shows correct data)

Zeus-Cerbo works at 250 kbps (Zeus shows up as an device on Cerbo)

There is no way to get data flow between all 3 devices at the same time.

Also, we know that NMEA2000 is 250kbps so using only that bitrate is the only thing that makes sense to me.

Still working out the details with Arco.. Perhaps there is something I dont understand here.

Matt

4/7/25, 6:22 AM

Ok, glad it's not just me. I did tell ARCO that their documentation sucked...they agreed.

I don't believe that the Zeus participates in DVCC while configured as a rec follower, but at least throttles back the charge as the cell voltages approach the setpoint.

Trond

4/7/25, 7:43 AM

My Zeus automaticly updates to "Zeus Firmware v1.23".

An firmware version not yet shown on their webpage, so must be new.

I also tested Victron Follow in our Lynx BMS NG setup.

And in Victron Follow, it runs at 250 kbps so this kind of works.

The only problem is, when you choose Victron Follow, it no longer shows up on Cerbo ;)

Just shows up as "disconnected".

I basicly have to restore to default settings to restore data to the Cerbo.

Again, it can not listen to the data from BMS NG, and send data to Cerbo at the same time.

Atleast that is how it seems like to me.

Matt

4/7/25, 7:48 AM

Odd, I'm nowhere near the boat at the moment, but that firmware seems to ring a bell. Mine did show up on the cerbo as a Victron follower, with the can set to lynx bms ve.can but without the Zeus receiving any useful data.

I did discover that the two can busses supposedly don't share data which is odd as I was under the impression that the dvcc data was pumped out everywhere.

https://ogm-energy.com/community/ogm-user-forum/topic/154310/new-rec-bms-and-victron-cerbo-dvcc-integration-guide

Rick OGM Support Staff

4/7/25, 7:53 AM

I think you may not have your Cerbo VE.CAN port set correctly. It needs to be 250k. Check out this thread for help. We sent Arco an Active BMS to test last year so they should have everything they need.

Hoping to have our Victron/Zeus/WS500 REC test system up and running next month. Because it needs an engine driven alternator, it makes it much more difficult to shop test.

Trond

4/7/25, 8:08 AM

@Rick Not sure thats the problem.

The fact that you can use the REC on 250kbps in VE.can network is old news.

It was an requirement to use the WS500 and this is what I am now testing on Zeus.

But it will not work on 250 kbps, only with REC sending at 500 kbps.

So In the Victron BMS NG setup, I have the Cerbo is setup for "VE.Can and CAN-bus BMS (250)".

Cerbo sees the Lynx Smart BMS, and Zeus syncs to the BMS as well.

The monent you choose "Victron Follow, Zeus is disconnected from Cerbo, like it stops sending data.

But at least in an Victron follow setup, they all stays on 250kbps.

Matt

4/7/25, 8:13 AM

I did briefly try doing that (changing my rec to 250k and configuring the can for ve.can and bms) but didn't have any luck. At the time I wasn't putting too much time into it as other projects were more pressing. For the active is cans 2 or 25? I've got the documentation on the boat and can't find it online right now.

Trond

4/7/25, 8:14 AM

I hooked up an test setup this morning in 30 minutes.

No motor or alternator needed really. IF you want to test field current just add an 12V bulb.

Just an Zeus, REC BMS with cells, (plus12V battery is handy) and an Cerbo.

I do have an signal generator if i need to simulate RPM from alternator.

Rick OGM Support Staff

4/7/25, 8:15 AM

Thanks Trond, once we get our inhouse test engine working and brckets and pulleys made, I will hopefully be able to share some insight

https://www.rec-bms.com/wp-content/uploads/2024/09/UserManual_ABMS_Victron.pdf

Trond

4/7/25, 8:17 AM

@Matt CANS 2 =250 kbps, CANS 3 =500 kbps

Page 15:

Matt

4/7/25, 8:24 AM

@Trond Røsvik thanks. I'm just blind. That is what I tried. Once I get back to the boat I'll try again just to be sure I didn't screw up my first attempt.

Trond

4/7/25, 11:13 AM

@Matt Looking back in older manuals like 2.8 I see that it used to be:

CANF 250 and CANF 500

So seems like they changed this in 2.9X.

Just start by sending CANF? or CANS? and see what reply you get.

Or even better, update the A-BMS to 2.94.

Matt

4/7/25, 4:51 PM

@Trond Røsvik I'm on the newer/est version of firmware. I should be back to the boat in a weekish. I do know when I changed the comm rate with CANS the bms accepted the change. I didn't screw around with it for too long as it was mostly working at 500k. But now I feel the need to really give it a try.

Trond

4/8/25, 3:47 AM

So far what I have found:

NMEA data for Battery, Engine and Charger all neds to be enabled for the Zeus to show up on Cerbo.

Disabling this, gives you no data.

Just make sure you choose an instance that is not already taken on the NMEA2000 network, as the default is 1. In my case this created an conflict. If I remember correctly Wakespeed chose instance 50+ just for this reason and only later gave the option to change it at your own will in SW.

REC follow and Victron integration at the same time is simply not working as the Zeus is listening to REC on 500 kbps and sending NMEA2000 on 250 kbps, all on the same network (!). It just does not make sense. Trying to get Arco to change this to all be 250 kbps.

If you choose REC BMS Follow the Zeus will disapear from your Cerbo, and changing Sync mode back to Disabled will not bring it back until you power cycle the Zeus to reset it.

This took me a while to understand, and with much frustration I may add...

In therms of Victron follow this kind of works.. just know its not DVCC, its directly reading the data from Lynx Smart BMS NG. And the Zeus will automaticly send volt, ampere and watt = 0 in this mode.

So again, you can integrate the Zeus with your Victron BMS, but then you loose data from alternator in Cerbo.

In fact, it will ignore DVCC commands.. So if you limit charge to 1A and 10V the Zeus will ignore this and just follow the instructions from the Lynx Smart BMS with full bulk mode and 100% field if needed.

There is mucht improvements to be done here...

Matt

4/8/25, 8:42 AM

Thanks Trond. This sounds much like my experience. I was approaching the "rip out the Zeus and replace it" phase.

did you happen to try the REC at 250K and with the cerbo set to 250k bms and the Zeus to Victron follower?

Trond

4/8/25, 8:55 AM

"REC at 250K and with the cerbo set to 250k bms and the Zeus to Victron follower".

EDIT: I noticed now you said Victron Follower. Yes I tried this. And it does not work.

It does not read DVCC data, looks for Lynx Smart NG data directly I belive..

Rick OGM Support Staff

4/8/25, 9:33 AM

This dual baud rate issue explains a lot. I havent had any luck with my contacts at ARCO, but that was a while back. It might be nice if we could get some insight from them. I am going to try Nick, but Trond if you know someone better please let me know.

Trond

4/8/25, 9:55 AM

My contact has been with Rob and Chris, but I guess they are more of an sales team.

Nick is probably an better bet, will try to get his contact info.

We have been dealing REC for 15 years, Victron for 20 years, Wakespeed since 4 years(?) and now Arco. If I can not get this to work, neither can any of our customers.

Rick OGM Support Staff

4/8/25, 10:12 AM

Good point. Thanks for sharing all of your testing and insight. I have Nick's contact info buried somewhere so I am going to ask him to reply to this post.

Matt

4/8/25, 2:27 PM

I've been speaking with an engineer (who I sense is new to Arco or the Zeus project). But his name is written down on the boat and I'm on a drilling rig right now.

Trond

4/9/25, 4:55 AM

I also discovered that in Sync mode (both Victron and REC) If the Zeus looses connection with the BMS it will just continue in Bulk mode and refering to the last known battery voltage.

Essentually overcharging the battery.

Even worse:

The default setting is Limp Mode=on and 20%.

If you then enable Victron Follow and Zeus dont see the BMS for whatever reason it will then go directly in to Limp mode and give field 20%.

Does not matter if the voltage is out of range it will still keep going at 20% field "forever".

EDIT: default Limp mode is 5% out of the box, but if you reset to factory reset in the app, it becomes 20%.

Matt

4/9/25, 7:12 AM

Also, once it's been connected to a can buss it will ignore the battery sense.
I installed that as a backup to the can network and was dismayed to find the battery voltage measurement ignored.

i didn't know about the staying in bulk if the comms are lost. Now I'm a bit terrified.

Trond

4/9/25, 7:33 AM

So basicly the "battery voltage" just freezes and it continues full speed.. there is no stopping it.

Disconnected the CAN cable 3 hours ago, still giving out 100% field.

Acually if I turn Sync mode off then back to Victron Follow, it will refere to the voltage the way it was on the Can bus 3 hours ago.

EDIT: I extended the test by swapping the battery for an adjustable power supply (0-60V) and confrmed the same. Absortion is set to 14.1V and "out of range =16V)

Tested with battery voltage 17V , 27V, 37V and the Zeus still holds full bulk mode at 100% field.

It does not read the battery sense, only the voltage last seen on CAN bus before it was disconnected.

Matt

4/9/25, 7:45 AM

Trond,

have you tried to apply a "battery" voltage to the battery sense leads? On mine they don't sense anything.

Trond

4/9/25, 7:55 AM

In sync mode "disabled" it does read the voltage correct.

But alternator volt is always 0V, even thought the volt sense is connected.

Even unboxed an second Zeus to rule out HW failure.