I'm currently planning our my upgrade to Lithium from Trojan T105s and am wondering which pins on the REC Active BMS should connect the following to:
- Victron Battery Protect (for charge disconnection of solar)
- Victron Phoenix Smart Charger AC Charger remote (for charge disconnection)
- note: I may also have a Cerbo connected
- Alternator Shutdown (Victron SolidSwitch 104 connected on igition signal to Balmar MC-614)
- BMS input on REC Pre-Charge Module V3.1 (pin #9)
- (I haven't seen any diagrams for the V3.1 version :( )
ps. I do have an BMS controlled charge bus and load bus contactors
If you have a Cerbo connected to your REC BMS and have your CANBus connected with CVCC/DVCC mode enabled most of this can be done automatically by the BMS. It will even throttle back the Solar and charger output at it approaches 100% to allow for smooth top balancing
If you want to hardwire it for redundancy:
There are 2 spare opto outputs that can be easily configured using the wifi module. Depending on the current load you may need to add a small interposing relay. Just set the cutout a bit higher than the top balance setting or at about 3.65V
Get a DPDT relay so you can wire your solar through one contact and your alternator enable through the other.
There is also spare relay output that is usually used to disconnect external loads that can be used as well, but it seems you already have a dual bus system so that will be used for your second contactor.
Here is a link to some sample drawings that may help.
https://rec-bms-na.com/rec-bms-sample-sketches/#22-31-wpfd-rec-active-bms-sketches
Good luck with your project!
Rick,
Thanks for the feedback.
The only diagram I could find that uses the V3 pre-charge is: https://rec-bms-na.com/download/31/rec-active-bms-sketches/1290/rec-active-bms-wiring-diagram-rec-active-bms-2p4s-1-relay-precharge_3_0.pdf
This diagram is quite different than the manual. Do I understand it correctly that in this diagram that the Pre-Charge unit is powered down until needed by the BMS (power to the pre-charge flows through the BMS main relay)?
Although it seems that pin4 (Pack +) is in the wrong place and there is no pin to do the actual precharge - what am I missing
Looking at the diagram in the Pre-charge manual I think if the REC-BMS is used (vs REC Q) Pin 8 is system ground and then the main BMS relay (Relay DCH NO/F on the REC BMS) is used to swtich the ground to Pin 9 (BMS input ground) - correct?
thanks,
Geoff.
@Geoff
Thanks for the note about the missing precharge wire. Its now been added and the sketch updated.
You can download it here: https://rec-bms-na.com/download/31/rec-active-bms-sketches/1464/rec-active-bms-wiring-diagram-rec-active-bms-2p4s-1-relay-precharge_3_0.pdf
Also, you are correct, this configuration only powers the precharge when the system is powered up. Page 8 of the Precharge 3.0 manual explains it a bit.
Rick,
Thanks for the update - things make more senses now!
One question - on the updated diagram shouldn't pin4 (Pack+) go to the battery pack side of the contactor?
For an actual install should you have a fuse on the pre-charge line, or is it okay without? (I think normally anything connecting to a battery needs a fuse?)
