question

carl-dewever avatar image
carl-dewever asked

REC ACTIVE BMS and relays...

Hello,

I am totally desperate... I have read lots of manuals, forums etc but i am stuck.

I have a

  • REC ACTIVE BMS
  • victron Cerbo GX
  • victron multiplus
  • 820Ah 12V lifepo
  • victron battery protect discharge relay
  • victron buckboost dc/dc charger to charge from my engine alternator


Although the documentation of the RECABMS speaks about 2 relays (relay chg no and relay dchg no) I understand that if you install firmware 2.90.1 only one is used, being the "relay dchg no", also called the UV.

As I need to
- switch off my DC loads in case of undervoltage through the battery protect
- and switch off my buckboost charger in case of cell overvoltage I installed firmware 2.90.2 which states that the undervoltage and over voltage relays are separate.

So I thought : this is my solution.

But it does not work as intended :

stopping discharge when cell voltage becomes too low
I have connected my "relay dcg no" cable to my "battery protect" H input and when the measured cell voltage drops below the "cell min voltage" of the BMS beeps and the "relay dcg no" goes to 0V and the DC loads are shut off, which is desired and perfect.

stopping charging when cell voltage become too high

When the measured cell voltages are below the max cell voltage, the buck/boost charger charges : perfect
This is normal as the "relay chg no" is at 12V.

However, when the voltage get above the "max cell voltage", the BMS beeps but the "relay chg no" stays at 12V so the buck/boost DC/DC charger keeps on charging.

This is not what I want and not what I expected. I had expected the "relay chg no" to go to 0V and switch off the buck/boost dc/dc charger.

Can anyone explain me what I'm doing wrong? Or is there a bug in the firmware as the readme.txt of the firmware seem contradictory to me.

Thanks for all the help.

BMS
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1 Answer
rick-ogss avatar image
rick-ogss answered ·
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.