n00b question re: over-discharge protection

[Merlmabase]

Hi folks. Just received my 280h EVE cells, Multiplus 24/3000/70-50, and Overkill BMS in the last couple of weeks. Starting to configure everything and run through a couple of charge cycles just to get the hang of things. No solar panels/SCC yet, waiting until I can start working on converting a vehicle in the spring.

I have a question about over-discharge protection. I know on the charging side, you should have parameters set at the SCC and inverter/charger, with BMS cut-off being the last line of defense.

Does the same apply for discharging? I can set inverter parameters for a low-voltage cut-off, but for my DC loads there's nothing but the BMS protecting the cells from over-discharge. Am I missing something? Should there be another component monitoring discharge and able to cut loads at a given voltage? I also have that cheap shunt/monitor that Will likes, should that play a role?

Very grateful for your help.

 

[snoobler]

Your multiplus has a low voltage disconnect. You can customize it with VE Configure and a suitable interface.

 

[Merlmabase]

Yeah, like I said, I know I can program a cut-off for my A/C loads. My question was, for my DC loads, is there any redundancy when it comes to discharge cut-off? The Multiplus has no role in that system.

 

[snoobler]

Oof. Reading fail. Sorry about that.

If you have the DC loads connected to SCC load ports, then many have provisions for cutting them off.

Victron sells a Battery Protect for your stated purpose.

 

[Hedges]

Yeah, like I said, I know I can program a cut-off for my A/C loads. My question was, for my DC loads, is there any redundancy when it comes to discharge cut-off? The Multiplus has no role in that system.

Is your inverter always running?
Set up a relay with AC coil to connect DC loads.
If you have a SCC with load connection have low battery disconnect, could wire that to a DC coil relay.

 

[Merlmabase]

Is your inverter always running?
Set up a relay with AC coil to connect DC loads.
If you have a SCC with load connection have low battery disconnect, could wire that to a DC coil relay.

I was hoping to set up the inverter to run only as needed, but that does offer an interesting solution. Thanks!

 

[snoobler]

I was hoping to set up the inverter to run only as needed, but that does offer an interesting solution. Thanks!

The only way you're going to accomplish the above is by manually turning it on and off. Some have a low power mode where if the load drops below X, they go dormant and stop providing loads, but they will still consume power in that manner. Savings may only be 40-50% of max.