I'm looking at at least two contactors (actually EGIS relays), one for the charge bus and one for the discharge bus. My current design (which I'm reducing as we are changing from 12V to 24V) has 2 of each. This is where the questions come from:
If I have multiple contactors
- I assume each one needs a pre-charge of it's own? Or do I really need that (depending on what is on each contactor?)?
- Where should a victron multiplus go? (neither the charge nor discharge on their own seem right...) - or would I need a charge/discharge contactor for it?
Hey Geof,
Some good questions.
1) the Rec 2Q has an adjustable precharge circuit built into it and its only used on the load thst includes your inverter as it is an inductive load, usually your OV bus.
2) most modern solutions use a single contactor as.an overall safety, and your victron inverter/charger will automatically be controlled and disconnected by the REC BMS using DVCC control. Cerbo setup is included in the 2Q quickstart manual.
If you want to stick with a dual bus then i would put the inverter charger on the OV bus, as that worst case scenario, a dead battery is better than an overcharged one.
Hope that helps,
Rick
Rick,
Thanks for the reply. It sounds like you recommend a single contactor/relay?
Regarding precharge: I understand that when the contactor switches you want the pre-charge to ensure you don't get a huge inrush current draw charging up the inverter capacitors etc. I will also have a 24V watermaker (600W or larger motor), electric winch and windlass (1000W). When the contactor switches they will be off, so no problem there. Is there any concern on the inrush to these devices when they are turned on?
Can you point me to the 2Q quickstart manual - I haven't been able to find it (just the "REC BMS 2Q to Victron Cerbo Interface Guide").
thanks,
Geoff
@Geoff Hey Geof, the Quickstart manual link will be in the REC Tech info email that is sent right after your REC order was confirmed.
And yes, if you have an integrated system a single saferty contactor is the norm now.
For your other loads, they do not need a precharge. The precharge is only to slow charge up the big capacitors on your inverter, as the inrush current can be very high otherwise, causing arcing and EMI.
Looking at the 2Q manual it looks like if I want OV and UV disconnects, then I can't use the standard Opto-Relay as it is only intended for controlling a single contactor.
So I'd need to use the Optocoupler 1/2 signals to control the two contactors. (no issue there) Since I don't think you can use the Opto-Relay, the pre-charge circutry in the 2Q can no longer be used, so I'd be forced to add the pre-charge module. Is this correct?
... begining to think it may not be worth it to have OV and UV contactors given the extra complexity for the rare chance of an UV or OV disconnect.
