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Rec BMS charge and discharge disable

  • R
    Hi- Thanks for putting this forum up. I\'m interested in the REC BMS for a future boat install using a Victron and Wakespeed based system. Understand that the primary charge/discharge control will be via Canbus to the inverter and regulators. From reviewing the Rec BMS documentation, I\'m a bit confused as it only shows a single relay to shut-down the inverter/charger. Can I set up the Rec BMS with one of the guessing MOSFET switches be charge disable and the other be a discharge disable?  In other words separately control charging and discharging similar to other BMS solutions out there? I would like to control some non CAN controlled chargers and load sources via a few Victron battery connects.   thanks,   robin    
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  • R
    Hi Robin, Early on in the BMS era we needed to have separate UV and OV circuits to protect our systems.  With the advent of \"Smart devices\" using CANBus it becomes less of an issue. As you mention the devices talk with each other and the BMS effectively acts as the Master battery protection device on your network.  It will throttle back your WS500s, your MPPTs and your Victron or SMA inverter and chargers to maintain a safe system, with a single disconnect as a fail-safe mechanical disconnect.  In addition the opto output can be used to disable the charger on an older charging device.  You can even add an interposing relay and have it shut down your alternator field, battery charger, MPPT, wind, etc but keep in mind these methods are old binary control technology and do not lend themselves to a nicely regulated self compensating control system. That all being said, if you would like to split your charge and load buses that is fine too.  You just need a quick firmware swap that can be uploaded from either your wifi module or PC software.  Just send us a quick email with your order number and BMS serial number and we will have head office set you up. Hope this helps!!
  • R
    Thanks from user Ben, who reminded me that with the WS500, unlike older external regulators, you would disable it or remove its power instead of using the field wire.
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  • A
    Hello, I\'m looking at the Rec Q BMS for my existing 24V system in my van.  The title of this thread just mentions REC but it is in the REC Q subforum so I hope this is the right place. I have a 24V DIY bank, Victron equipment including a 24V Multiplus, and am planning to add the 24V Wakespeed/Nations alternator.  I am trying to understand the non-CAN charge/discharge control capability of the REC Q BMS. I know I could control my Multiplus, MPPT, and the Wakespeed via CAN.  However, I also have DC loads controlled by a Victron BatteryProtect, and a Victron DC-DC charger--neither of which support CAN.  Thus, I also need binary charge and discharge control, in addition to CAN. Looking at the REC Q manual, I see only one charge relay control, no discharge relay and no optocouplers--unlike the REC Active BMS.  Rick\'s response above speaks to binary control of chargers--but not control of discharging into DC loads.  Is there a way that I can control both my non-CAN DC loads and my non-CAN DC-DC charger with the REC Q BMS?
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  • R
    The Q Series actually includes an Opto relay for interlocking manually with a non CAN charging device.  On a rise in cell voltage the BMS first toggles the opto relay, then if the voltage continues to rise it then disables the main contactor on either an OV or UV condition.  I have attached a sketch similar to what you are describing for your reference.  There are also more PDF examples as well as diagrams.net XML drawing files and libraries available here. REC North America Downloads link:    https://rec-bms-na.com/downloads/ And we have created a 20 minute tutorial on how to create your own drawings using our symbols libraries and the free online tool diagrams.net Tutorials link:  https://rec-bms-na.com/tutorials/
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  • A
    Thanks for the reply.  But again this just addresses charge control, but not discharge control.  Is there a way to control my Victron BatteryProtect to disable DC loads if the battery gets too low?  I need both binary charge control (based on OV) for my DC-DC, and also binary discharge control (based on UV) for my DC loads.
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  • R
    I think that REC may have a solution for that later this year.  I will post something when I get more details.
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  • A
    Thanks, please do.  What would be ideal is a REC Active BMS that supported 8s.  The Active BMS is a nice unit and seems well suited for the needs of vans, RVs and boats with a mix of charging sources and loads.  But unfortunately I\'m already at 24V and can\'t change at this point.
  • E
    Hi! Wondering if there have been any updates on this. Thank you!
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  • R
    There is another thread similar to this one where they want to use the SI-Q BMS opto output for discharge limit disable of loads, in this case to isolate the Cerbo and only have it disabled on a low voltage  We are just waiting for feedback from REC head office on how to do it. https://www.offgridsoftwaresolutions.com/ws500-user-forum/topic/controlling-cerbo-gx-with-rec-bms-hibernate-switch/?part=1#postid-857
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  • B
    I have setup multiply REC Q BMS 24V system with one discharge relay and one charge relay. REC can supply you from a firmware that the opto output controls the Charge relay. The relay output controls the Discharge(load). In general the setup is describe in the RECmanual, NON Victron setup. Ask REC for firmware, Qbms, \"\"separated relay version\"\" version including Victron CAN support. You can not download this from there website, because for the Qbms, the firmware has the serialnumber for your bms in it. This means I can not share the firmware I use. But your dealer can supply you from this firmware, or ask REC directly. On the opto output I use a SSR to control the main relay. Ben    
  • E
    Nice, thank you. I will contact them when closer to doing my install.
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  • s
    It seems like REC made a mistake by not providing additional relays for Allow-To-Charge, Allow-To-Discharge, Aux, etc to account for none smart devices and critical loads like the Cerbo GX. It would be nice to have the flexibility of multiple relays instead of getting custom firmware.  If REC releases a new version of firmware with interesting features the user would have to again request a custom version.  Would they charge 25 Euro again for the custom version?  Are the custom versions tested with the same rigor as the main releases? I assume the limitation is their hardware design.  I hope REC is listening/reading if they ever plan an updated model.
  • B
    The REC-Q serie has 2 outputs, one from this can be used as ATC, to switch off non victron compatible chargers. Both outputs programmable by customer. (No new firmware needed)   REC ABMS has 4 outputs, can be programmed by customer. Plenty off possibility to program ATC or ATD.
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  • s
    Quote from Ben on March 10, 2023, 12:13 am
    The REC-Q serie has 2 outputs, one from this can be used as ATC, to switch off non victron compatible chargers. Both outputs programmable by customer. (No new firmware needed)   REC ABMS has 4 outputs, can be programmed by customer. Plenty off possibility to program ATC or ATD.
    Ben, I hope you can help me understand how to configure the REC BMS.  I\'m getting close to connecting it to my 8s LifePO4 battery pack.  I\'ve read the documentation but haven\'t played with the settings yet. I have the Q series with Victron CAN compatibility.  I\'m using one output for the REC precharge module. That leaves one output.  According to the REC documentation the relay (optocoupler?) appears to be ATC (Over Voltage Protection for chargers).  I didn\'t see anywhere in the document where that relay can be configured for ATD (Under Voltage Protection for critical loads). What is the default operation of the optocoupler output, is there a way to change it between ATC and ATD?
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  • B
    The charge relay is controlled with command RE1L and RE1H.   Not with CMAX.
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  • R
    Yes, all parameters are programmable by either the PC software or the Wifi.  The only difference is that with the new firmware there is a new feature called Tasks that also allows custom configuration of the spare outputs. You may even find that you will want to go back to the 2.9.0-1 version and custom config your second relay or opto outputs that way. You can get everything from here: https://rec-bms-na.com/downloads/
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  • b
    I have a general observation to share. After installing firmware v2.9, we discovered that negative values for Opto(x) CH Hysterisis (OPxH) are no longer supported. Although the system allows for negative values to be set, the negative sign is not persisted after the first BMS reboot. As a result, the OPxH parameter is saved as a positive value. In our case:
    • we set OP1L to 3.6V and OP1H to (-0.25) for BatteryProtect solar control,
    • and OP2L to 3.6V with OP2H set as (-0.25V) for combining LFP with AGM via Cyrix.
    Fortunately, we rebooted the BMS after upgrading to v2.9 and realized that something wasn\'t right. Unfortunately, this change was not documented in the manual. We had to downgrade to v2.6 to keep the system running without making any hardware changes.
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  • R
    I would think you only need 2.9-2 if you have an older system and do not have the Wifi module
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  • B
    at Carl Dewever: \"\"hello, thx for that info, however, where can I find that kind of info? It looks like I\'m missing some documentation... can I program these 2 parameters with the wifi-module? thx carl\"\"     Programming: \"\"The charge relay is controlled with command RE1L and RE1H.\"\"   See manual, download https://www.rec-bms.com/rec-active-bms/     WS500 an Victron compatible version. (Rick, I think your website has not the correct manual!!)   See pag 15,  :     OUTPUTS SETTINGS INSTRUCTIONS   The wifi browser page, has a few settings easy to set under \"\"settings tab\"\". Some settings need to be programmed under: Firmware/Manual communication. See details in WIFI manual. In short: Address type \"\"2\"\" Message type  \"\"RE1L  3.60\"\" press submit. check or settings is correctly programmed. type  \"\"RE1l?\"\" Press summit. read out.
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  • B
    Quote from Rick-admin on March 16, 2023, 1:50 pm
    I would think you only need 2.9-2 if you have an older system and do not have the Wifi module
    Hi  Carl. So far as I know there is not a version 2.9-2. (But maybe I dont have the latest info) There is a version 2.9.0-1 and 2.9.0-2. In the download link from https://rec-bms-na.com/product-manuals/##7-8-wpfd-rec-active-bms There is inside the ZIP file a txt document which explain the 2 differences. If  the info you search for is not in this document let us know.
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  • B
    Quote from bonsys on March 16, 2023, 12:19 pm
    I have a general observation to share. After installing firmware v2.9, we discovered that negative values for Opto(x) CH Hysterisis (OPxH) are no longer supported. Although the system allows for negative values to be set, the negative sign is not persisted after the first BMS reboot. As a result, the OPxH parameter is saved as a positive value. In our case:
    • we set OP1L to 3.6V and OP1H to (-0.25) for BatteryProtect solar control,
    • and OP2L to 3.6V with OP2H set as (-0.25V) for combining LFP with AGM via Cyrix.
    Fortunately, we rebooted the BMS after upgrading to v2.9 and realized that something wasn\'t right. Unfortunately, this change was not documented in the manual. We had to downgrade to v2.6 to keep the system running without making any hardware changes.
    In the NON victron firmware, the opto 1 and opto2 are controlled by the OP1L and OP2L commands. In the Victron/WS500 Firmware from website: https://rec-bms-na.com/product-manuals/##7-8-wpfd-rec-active-bms Opto 1 is controlled by the command CHAR and CHIS (Can be set for ONLY Charge control) opto 2 is controlled by OP2L and OP2H  (CAn be set for charge OR load control) Please let us know, or you can set the correct values, also the negative Hysterisis for OP2H I understand that this can confuse users.  Maybe your 2.6 is a non Victron firmware? And you updated with the Victron compatible version.  
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