Hello,
I am currently laying out and planning my setup for a boat conversion to LiFePO4 that I want to do. I will install 560Ah of LiFePO4 (2P4S EVE cells), a REC Active BMS, Cerbo, WS500 and Balmar XT170 alternator, as well as Multiplus and a Smart MPPT and some other parts.
I can figure out most of the proposed wiring. However, regarding the Smart Battery Protect, Cerbo and WS500 I have a few questions:
The VE.Bus BMS offers very handy connectors for Charge Disconnect and Load Disconnect, supplying input voltage - 1V. As far as I can tell, the REC BMS does not provide a similar functionality out of the box.
The Cerbo Power+ and SBP Remote H have to be connected to the \"Load Disconnect\" pin. The Cerbo needs something upwards of 8V to function correctly. Do I have to use the opto couplers of the REC BMS for this? So use the opto relays to switch an opto coupler which then provides a high-enough voltage?
Then regarding the WS500: In the proposed schemas by Victron the Charge Disconnect is always wired into the Feature In cable of the Wakespeed harness (for example here: https://www.victronenergy.de/upload/documents/MultiPlus-3KW-230VAC-12VDC-600Ah-Li-Lynx-Smart-BMS-&-distributors-Cerbo-GX-touch-generator-MPPT-Extra-Alternator-&-WS500.pdf). Would this be a similar approach as with the Load Disconnect, to use the opto relays for this?
It would be amazing if this could be added to the REC BMS + Victron schematics that you provide.
Thank you so much,
Sebastian
Hi Sebastian,
The REC Active BMS has a spare relay output and opto output that can be programmed to cut in/out at a desired voltage, so one for your Cerbo and one for your WS500 feature In should work for you.
For drawings, we have posted our samples to the
https://REC-BMS-NA.com website in xml format, that can be edited using diagrams.net. And in the Tutorials section we have also included a primer video on how to get started using it.
Good luck with your installation!
Hi Rick,
Thank you very much for your reply!
However, I don\'t understand yet how I can use the optocouplers inside the REC BMS to behave similar to the main relay (opening for OV and UV), so that I can use them for powering down the alternator, in case the main relay is about to be opened.
Example:
1. We are motoring, the alternator is pumping in energy, but we are also running big loads, so we are still draining the battery.
2. We are nearing a depleted battery. The REC should now tell our loads (via Cerbo, etc.) to reduce loads or switch them off. But let\'s just say for some weird reason, this did not work (in case of CAN failure i.e.)
3. So as a last resort the REC has to open the main relay to save our batteries from discharging too far.
In this scenario, the WS500 and alternator never received the information to stop charging and a voltage spike might occur!
Is this just me being paranoid? Or am I overseeing something? Does the first opto-coupler already behave the same way as the main relay?
Thank you very much!
If this is a concern in your configuration you have a couple of options
- Break out these large loads onto a separate bus and use a second contactor to disable these loads when you have a cell go under 3 volts and make sure you give it a good deadband(hysterysis) so they dont short cycle.
- If we are just talking about one or two loads, and I am guessing they are aircon units, I would do this. Wire in a multi-pole 10A relay into RE1 or Opt2 and just interrupt the thermostat \"call for cooling\" wire. Your aircons will simply shut off until your system recharges. Figure 1 in the Active BMS for Victron/Wakespeed depicts an example of this. You can find it here. https://rec-bms-na.com/product-manuals/#7-8-wpfd-rec-active-bms
- And if you have a N2K display you can set up a low voltage alarm at your display and manually turn off your big loads before you get a trip
You do not want to add an interlock to disable your WS500 on low voltage or you will never be able to recover from a low voltage condition as your alternator will be disabled. Instead you want to look at ways to shed your loads. You should also incorporate some sort of Alternator protection device, like a B2B charger. We talk about this and interlocks in another post on the forum in a bit of detail.
Here are the parameters where you set these values
Hope this helps
Rick
Hello there,
I am in a similar situation.
I have installed the following:
1) CALB lifepo4 180 amp batteries in series of 8 to create a 24 volt bank. I have 2 of these banks one in front of the other in parallel to create my bank of 360 ah / 24 volts.
2) Victron Multiplus 24v 3000 watt 70 amp charger
3) Balmar 24v 150 amp 624 model alternator along with their regulator. I am concerned with the load dump to the alternator if the BMS cut off the batteries
4) My current BMS do not have cam outputs so I need to replace them.
I need a solution to integrate these three components. I would like to integrate the Victron CerboGX to allow me to monitor what is happening and also to add integration with a Victron MPPT controller in the future.
I have been pouring though the manuals of various components and seeking advice from various people. I am more confused than when started.
Rick could you recommend the components that will communicate with each other and and your thoughts.
Thank you for your time.
Gary
Hi Gary,
In a 24V system you would use the REC Q Series BMS to provide the following functionality:
- connects to your Victron Cerbo and becomes its DC source. Some page snips of what it looks like within the Control Panel or VRM are attached for reference
- through the Cerbo, it will throttle your Victron charger and MPPT on a high voltage to keep from overcharging your pack while still allowing enough current to perform a top balance.
- directly via CANBus it will throttle your WS500 to keep your alternator from overcharging your pack.
- the opto output can be used to disable dumb type charging devices directly
- as it approaches a low voltage state it will disable your Victron inverter through the Cerbo
For a dump safety you can look at a couple of options:
- Victron or Sterling B2B charger to your charging battery(my preferred)
- Sterling APS alternator protector
- Or some people have elected to add a 24V LA battery in parallel as kind of a sacrificial battery(not something I have tried or would recommend)
- add a parallel relay across your contactor that will break the alternator field wire (I also do this)
- with the same relay interlock your charger/inverter enable circuits
I am attaching a wiring sketch that shows what the network wiring looks like from your BMS to your Cerbo, WS500 and your MPPT
Hope this helps,
Rick
