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REC and WS500 User Forum

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Long Term Storage with REC Active BMS - Victron Setup

Looking for advice on how best to configure the REC BMS for extended periods where the battery bank is not in use.  I have a 800ah 12v house battery bank on our boat monitored via REC BMS controlling a Victron Multiplus.  During periods where we aren't using the boat, the REC BMS basically just sits and cycles the battery bank from 100%-94%, recharge to 100% (repeat).

It is my understanding that ideally the LifePo4 battery bank would sit at ~50% SOC rather than 100%-94%.

I do reduce the End of Charge Voltage value when we aren't using the boat (but setting it below 3.4 seems to cause odd behaviors).

Any suggestions?

What has worked well for us was to just turn off the BMS when the pack was in the 60-70% range.  We have left it for more than a year and the pack was within 1% of where we left it.  You might want to grab a DC amprobe and do a bit of testing to make sure there are no parasitic loads that are not getting disabled by the BMS.

Another idea to explore if you have the WiFi module and internet at your boat yard would be to wire it on the battery side and it will go into a deep sleep when not used.  You can wake it up by connecting remotely to it using a browser.

There is a remote control opto relay on the WiFi module that I was thinking we could use to remotely enable/disable the BMS, but havent tried it myself yet.  I might want to add a micro relay to the circuit to actually power the BMS.

The idea is connect to your system via browser and turn on the BMS with this switch.  Your system comes to life and you can check all your cell voltages and pack status, then just turn it back off until the next time you want to check it.  We did the math on the load this would put on the cells over the long term and it was under 1% per year on a reasonable size system.

If anyone has this working please share it.

 

Hi,

I have a similar setup, including a Victron Cerbo GX. The REC BMS is connected to the Cerbo over VE.CAN, and the Multiplus is connected over VE.BUS to the Cerbo. This allows me to use the DVCC "Limit volt" feature in the Cerbo to change the max charge voltage for the Multiplus and MPPT controllers. I have for the last weeks set the DVCC voltage imit to 13,1v, and the battery is now "floating" at 50% SOC. Very easy to change the DVCC voltage limit through the Cerbo user interface or ModBUS TCP. In my setup, I use HomeAssistant and ModBUS TCP, and have made a simple switch to set the system in storage mode, simply changing the value from 14.1v to 13.1v.

Br

Sturla

That's a great idea!

Thanks for sharing

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