Finished! Boat refit, EVE 13.5 kWh, Victron, REC, Nordkyn, Blue Sea

ohthetrees

Solar Enthusiast
Just finished with my upgrade. Went from 4 tired AGM 160ah batt to 1120 ah of EVE cells in a spring-compressed fixture.

Battery:
16X EVE (amy) 280ah cells, separated by thin silcone sheets, fixtured with with hydro-cut aluminum end plates, threaded rod, and springs.

BMS:
REC Active BMS, talking to a Victron Cerbo.

Main contactor:
Blue Sea ML-RBS 500amp latching relay. Zero current hold.

Victron Stuff:
Multiplus 3000-12, Cerbo GX, GX50 display, 2X MPPT 100/50, Fet Isolator, Orion TR Smart DC-DC charger

Alternator control:
Norkdyn vrc-200 programmable external regulator


Cheers, and thanks! This forum was a big help!

IMG_0131 3.jpegIMG_0121.jpegIMG_0044.jpegIMG_0019.jpegIMG_0016.jpegIMG_0041B .jpg
 

Jokani

New Member
Just finished with my upgrade. Went from 4 tired AGM 160ah batt to 1120 ah of EVE cells in a spring-compressed fixture.

Battery:
16X EVE (amy) 280ah cells, separated by thin silcone sheets, fixtured with with hydro-cut aluminum end plates, threaded rod, and springs.

BMS:
REC Active BMS, talking to a Victron Cerbo.

Main contactor:
Blue Sea ML-RBS 500amp latching relay. Zero current hold.

Victron Stuff:
Multiplus 3000-12, Cerbo GX, GX50 display, 2X MPPT 100/50, Fet Isolator, Orion TR Smart DC-DC charger

Alternator control:
Norkdyn vrc-200 programmable external regulator


Cheers, and thanks! This forum was a big help!

View attachment 68884View attachment 68885View attachment 68886View attachment 68887View attachment 68888View attachment 68890

Nice set up, how did you get the ML-RBS to work with the REC BMS, my understanding is that they are not compatible?
 

ohthetrees

Solar Enthusiast
I have the “Main normally closed” (REC terminology) BMS relay output hooked up to the open(disconnect) signal wire on the ML-RBS.

The normally closed relay is open when the BMS is happy. When the BMS detects a fault, or is turned off, it closes the normally closed relay, which opens the ML-RBS. The ML-RBS has a “close” signal wire too, but I don’t use that, I just reset manually. Since the ML-RBS is the “last resort” and should never trigger a disconnect in normal usage , I don’t mind manually resetting, and in fact prefer it, because something is wrong if it triggers, and I want the opportunity to investigate. It’s been working perfectly for a month now, and hasn’t triggered, except during testing.
 

Jokani

New Member
Thanks for the info. I'm keen to try and get to 'zero current hold' if I can.

I did ask REC if their system was compatible with the ML-RBS, and they said no. I think because the REC system is designed to work with a relay with constant voltage rather than a pulse?

But it looks like that is only partially correct, and that although the REC cannot switch the ML-RBS both on and off, the REC can trigger a disconnect. That might suit me!

That being the case, I guess I could use 2 x ML-RBS, 1 for the charge side and 1 for the load.

Am I along the right lines?

What boat by the way?
 

ohthetrees

Solar Enthusiast
Thanks for the info. I'm keen to try and get to 'zero current hold' if I can.

I did ask REC if their system was compatible with the ML-RBS, and they said no. I think because the REC system is designed to work with a relay with constant voltage rather than a pulse?

But it looks like that is only partially correct, and that although the REC cannot switch the ML-RBS both on and off, the REC can trigger a disconnect. That might suit me!

That being the case, I guess I could use 2 x ML-RBS, 1 for the charge side and 1 for the load.

Am I along the right lines?

What boat by the way?
I even think the the REC could turn the RBS on (close it ) too. It is true that the RBS specifies a pulse, and the REC provides an always-on signal, so seemingly incompatible. However, I called Blue Sea, and spoke to a guy who seem to know his stuff, and he told me that while they haven’t tested, and don’t endorse it, he doesn’t think a constant signal will hurt anything. The only problem they’ve had is when someone sends a signal to both wires simultaneously and it tries to open and close at the same time.

Another option that I didn’t even know about when I bought my stuff is the ML-RBS 7718. The technician at Blue Sea suggested it to me, and it might be the best of all worlds. It seems to be pretty much exactly like the 7701 that I used, except it takes an always on signal, and automatically unlatches if the signal is removed. In other words it stimulates a regular solenoid, except only takes about 8 mA to hold closed. You should do your own research to make sure it is suitable


Regarding having two switches, one for charge and one for discharge, I think that is preferable. I didn’t do it that way because it would require too much rewiring of my existing system, and also since my REC controls all my Victron chargers, the RBS only has to act as a last safety resort, it is not a part of routine charge control. If it’s an option for you, it is probably a better way, except for the expense of the RBS.
 

svsagres

New Member
I even think the the REC could turn the RBS on (close it ) too. It is true that the RBS specifies a pulse, and the REC provides an always-on signal, so seemingly incompatible. However, I called Blue Sea, and spoke to a guy who seem to know his stuff, and he told me that while they haven’t tested, and don’t endorse it, he doesn’t think a constant signal will hurt anything. The only problem they’ve had is when someone sends a signal to both wires simultaneously and it tries to open and close at the same time.

Another option that I didn’t even know about when I bought my stuff is the ML-RBS 7718. The technician at Blue Sea suggested it to me, and it might be the best of all worlds. It seems to be pretty much exactly like the 7701 that I used, except it takes an always on signal, and automatically unlatches if the signal is removed. In other words it stimulates a regular solenoid, except only takes about 8 mA to hold closed. You should do your own research to make sure it is suitable


Regarding having two switches, one for charge and one for discharge, I think that is preferable. I didn’t do it that way because it would require too much rewiring of my existing system, and also since my REC controls all my Victron chargers, the RBS only has to act as a last safety resort, it is not a part of routine charge control. If it’s an option for you, it is probably a better way, except for the expense of the RBS.
Just to let you know, it’s entirely possible to drive the ML-RBS “properly” from the REC BMS, if you add a couple of passive components. All it takes is a couple of capacitors (100 microfarad 36v electrolytics will be fine), a couple of resistors, and a couple of LEDs. As the REC flips the main relay, it will charge one capacitor or the other, generating a pulse that will in turn trigger the ML-RBS.

I’m new to this forum, so don’t know exactly what the rules are about linking to elsewhere, but if you search for CatNewBee, cruisersforum, and ML-RBS, you should be able to find a copy of the schematic. It’s dead simple to build on a breadboard.

Edit: Cruisers Forum Link If you look at post #8, you'll see the schematic to pulse the ML-RBS to both open and close using a REC BMS. Pretty simple, and gives you a visual indicator as a side effect (the resistors and LEDs are there to discharge the capacitors).
 
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