REC BMS Connector

Hillbillybuddha

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Sep 9, 2020
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Can't figure out how to get the connector/relay to work.

Battery pos to 400amp Class T fuse to Connector (I forget which one but it's the one that I bought from the company that sales the REC BMS in the states) to On/Off switch, to bus bar.

Battery neg to shunt to busbar.

REC BMS wire marked "Relay DCH NO" when cross referenced to the manual is called "main relay normally open" which is the wire the manual says to use to connect to the small red wire on the connector/relay. The small black wire is connected to the load side of the shunt.

How do I get power to my bus bar through the connector?
 

TAS CPA

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You don't say which version you have, but if it is the REC Active, @BretS may be able to help, as he is one of the few that seems to have figured these out.
 

Hillbillybuddha

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Just another clue: the wire marked Relay DCH NO has no positive current. In fact all of the relay wires are neg. It is my understanding that the contactor needs power to energize the Relay and allow power to pass through.
 

toms

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The ones i have set up are as per this diagram.
With just the one contactor the wiring should still go back to the REC for both wires.
 

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Hillbillybuddha

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The ones i have set up are as per this diagram.
With just the one contactor the wiring should still go back to the REC for both wires.
Am I reading this schematic wrong? It looks like "main relay no" goes to the first contactor and the other wire goes to ground. Where does the other wire go back to the REC? Or maybe I misunderstand what you mean by "go back to the REC for both wires"
 

jwelter99

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You need to power the input to the relay inside the REC. This should be fused. The wiring harness will be labelled RELAY DCH F.

I run this to a 1A fuse that is powered from the battery side of the main contactor. If on the controlled side when contactor is off REC can not control the contactor.

Then the _NO one goes to the positive control line on the contactor.
 

Hillbillybuddha

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You need to power the input to the relay inside the REC. This should be fused. The wiring harness will be labelled RELAY DCH F.

I run this to a 1A fuse that is powered from the battery side of the main contactor. If on the controlled side when contactor is off REC can not control the contactor.

Then the _NO one goes to the positive control line on the contactor.
Ok. I'll go pick up a 1amp fuse tomorrow. Unless you think a 2amp fuse will be OK? I have a few of those laying around.

Edit: Thank you. The "signal" confused me in the diagram because nowhere else in the manual does it mention or cross reference a signal wire. But I totally get what you're saying and it makes since now.
 
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jwelter99

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Ok. I'll go pick up a 1amp fuse tomorrow. Unless you think a 2amp fuse will be OK? I have a few of those laying around.

Edit: Thank you. The "signal" confused me in the diagram because nowhere else in the manual does it mention or cross reference a signal wire. But I totally get what you're saying and it makes since now.

2A should be ok as well. The relay inside the BMS is rated at 2A and it has a 2A internal micro fuse. So in theory you need nothing external, but as it is not an easy to find fuse and not so easy to replace, I prefer an external fuse slightly smaller so, in theory, it will blow first.

As my contactor only needs a few mA to latch and operate a 1A is plenty.
 

BretS

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Did you get this figured out? For some reason, I didn't get a notice for the tag above and haven't been in here for a week or so. There were some issues that I had with the wiring being labeled different than the schematic - there is a table in the manual that had the correct labelling on it. Let me know if you need any more help. Mine works great, and I love it.
 

BretS

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I am using mine with Victron equipment and a precharger, so it is wired like this...
ABMS Victron and precharge.jpg
 
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BretS

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Here is the table, and the ones highlighted in blue are the ones where the labels didn't match the description on the diagram. Hope this helps.

1634333400564.png
 

BretS

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Are you using Victron equipment? If you are, let me know because there are some areas where the instructions were messed up there too...
 

fakinx

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Are you using Victron equipment? If you are, let me know because there are some areas where the instructions were messed up there too...
Bret, hi!
I registered just to talk to you about your knowledge with Victron stuff and REC-BMS. I’m designing a system for my boat which includes Winston cells, Active BMS from REC and CCGX, Multiplus, solar MPPTs and Orion DC-DC charger for using with alternator through LA motor battery.
What is your take about realibility of such system? I’ll test DVCC with Multi next week but I’m concerned about stopping charge when on shore power and from Orion, which doesn’t seem to communicate with CCGX. How do you suggest to wire H and L pins of Orion?
Thanx and all the best.
 

BretS

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Bret, hi!
I registered just to talk to you about your knowledge with Victron stuff and REC-BMS. I’m designing a system for my boat which includes Winston cells, Active BMS from REC and CCGX, Multiplus, solar MPPTs and Orion DC-DC charger for using with alternator through LA motor battery.
What is your take about realibility of such system? I’ll test DVCC with Multi next week but I’m concerned about stopping charge when on shore power and from Orion, which doesn’t seem to communicate with CCGX. How do you suggest to wire H and L pins of Orion?
Thanx and all the best.

Hey! Hopefully I can help you out...
I have found the reliability to be great for my application (5th wheel RV)! I have pretty much the same components in my system, except a Cerbo GX. For my Orion (12/12-30), I only use it on drive days (and not at all if the solar is doing enough), so I just set the voltage setpoints to cut off charging before my REC Active balancing setpoint - then, either the MPPTs, or MP (if on shore power) can finish off the balancing since they are controlled by the REC Active. My Orion is also setup to sense alternator output and start and stop charging based on the engine running.
I'm not sure what you are concerned about with stopping charge when on shore power? The Multi will charge to the point that it is set to cutoff on shore power, and then just pass shore power through. I will attach my values for all of my charge/discharge settings so you can see what I have. Let me know if I can help any further!
charge discharge settings.jpg
 

fakinx

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Hi Bret and thank you for your trouble of writing swift answer.
Your settings looks a lot like mine and since I hadn’t had time to test my system (it’s still in pieces on the bench and PS acting as alternator and in other configuration as PV cell). I can tell there is a problem with supply when Orion goes in absorption and charge with decreasing current and after simulated engine restart it started again in bulk with whole absorption time from the start. For my bench I use 60Ah @12V 4P setup and that scenario can trip HV event. I was thinking of using opto ch for H signal but just don’t know how to implement that. I’m using this signal now to cut charging relay between Orion and my charge bus but I think that’s not to good (to stop Orion abruptly). I’d much rather stop it through dedicated pins just don’t know how.
The second thought is about holding batt high. Have you found a way how to float battery at app. 60% with just pass through from multi? Keeping float at one’s settings is one thing but pack just sits on nearly 100% the whole time (or am I wrong about that)? That is something I would like to accomplish. BMS doesn’t allow charging until is about 5% off (in event opto ch cut the charge actually) but that is perhaps still to high?
To wrap this up, REC is managing MPPTs and Multi (through CAN bus and CCGX) but nothing else. That’s just too little in my opinion. BMS should (and I’m sure it can) stop or start other (not networked) devices whenever it sees fit and I just don’t know how to set it up…
 

BretS

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Hi Bret and thank you for your trouble of writing swift answer.
Your settings looks a lot like mine and since I hadn’t had time to test my system (it’s still in pieces on the bench and PS acting as alternator and in other configuration as PV cell). I can tell there is a problem with supply when Orion goes in absorption and charge with decreasing current and after simulated engine restart it started again in bulk with whole absorption time from the start. For my bench I use 60Ah @12V 4P setup and that scenario can trip HV event. I was thinking of using opto ch for H signal but just don’t know how to implement that. I’m using this signal now to cut charging relay between Orion and my charge bus but I think that’s not to good (to stop Orion abruptly). I’d much rather stop it through dedicated pins just don’t know how.
The second thought is about holding batt high. Have you found a way how to float battery at app. 60% with just pass through from multi? Keeping float at one’s settings is one thing but pack just sits on nearly 100% the whole time (or am I wrong about that)? That is something I would like to accomplish. BMS doesn’t allow charging until is about 5% off (in event opto ch cut the charge actually) but that is perhaps still to high?
To wrap this up, REC is managing MPPTs and Multi (through CAN bus and CCGX) but nothing else. That’s just too little in my opinion. BMS should (and I’m sure it can) stop or start other (not networked) devices whenever it sees fit and I just don’t know how to set it up…
No problem! I'm sure you could use opto ch, but I haven't learned how to do that either, as I haven't needed it. Maybe @the_colorist on here can help, he sold me my REC and has a ton of knowledge. Maybe message him if he doesn't chime in.
Mine holds SOC at 100% while I am on shore power, because it is generally a relatively short time (couple of weeks at most), so I have not worried about it. When I am boondocking (dry camping), my SOC cycles as it goes down at night and back up with the sun. When storing the camper for a long period of time, I reduce loads to just my Cerbo (with a hotspot plugged into a USB for remote monitoring) and my REC powered, and keep my MPPTs on. I then change one quick setting in the REC, "End of charging", to 3.36V (13.44V). This will prevent any charging above around 60% - effectively a float. Then, when I am going back out, I just change that back to 3.52V (14.08V). I suppose I could do the same on shore power, but haven't been overly concerned about it being held at 100%, even though many would say it is not good for them... Hope this helps! Let me know if I can help further!
 

fakinx

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No problem! I'm sure you could use opto ch, but I haven't learned how to do that either, as I haven't needed it. Maybe @the_colorist on here can help, he sold me my REC and has a ton of knowledge. Maybe message him if he doesn't chime in.
Mine holds SOC at 100% while I am on shore power, because it is generally a relatively short time (couple of weeks at most), so I have not worried about it. When I am boondocking (dry camping), my SOC cycles as it goes down at night and back up with the sun. When storing the camper for a long period of time, I reduce loads to just my Cerbo (with a hotspot plugged into a USB for remote monitoring) and my REC powered, and keep my MPPTs on. I then change one quick setting in the REC, "End of charging", to 3.36V (13.44V). This will prevent any charging above around 60% - effectively a float. Then, when I am going back out, I just change that back to 3.52V (14.08V). I suppose I could do the same on shore power, but haven't been overly concerned about it being held at 100%, even though many would say it is not good for them... Hope this helps! Let me know if I can help further!
Thx Bret. I’ll test damn thing next week more in detail and I’m sure will ask some more questions…
Opto couplers are not too hard to use. I had some problems understanding the logic but it’s simple really. They work as switches or as signals if you add +12V on one wire. It’s just usage of those with Orion (and battery protect) that confuse me…
 

BretS

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Just wanted to add this in case anyone with a REC is following this. Had to tweak the storage hysteresis to keep it from draining down too much. It has to be tightened up being in the flat part of the curve.1637329721947_charge discharge settings.jpg
 

carbon60

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Jan 8, 2021
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Ottawa
Hi @BretS , I’m planning on turning in my newly assembled system this week.

  • REC Q BMS
  • Victron MPPT with VE.Can
  • Victron MultiPus 24/3000/70
  • Victron CerboGX
I’m hoping you can advise on two questions:
  1. Can I daisy chain the CAN ports starting from the BMS, through the SCC, the MultiPlus, and finally the Cerbo? If so, which ports are used for that?
  2. On first system startup, with all equipment at factory defaults, what happens?
Thanks for sharing,

A.
 
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