Automatic Inverter Shut Off LiFePo4

[DLTooley]

Ok, I have a modest 4s 280ah bank with a dumb Daly 60/30 bms with a ten gauge p-. My inverter is a 600 watt GoWisthat has a lead acid low voltage activation of 10.6 which is way to low.

I don’t think there is a simple solution to this, but if anyone has any tips it would be helpful.

The critical load is a 250 watts, an oxygen concentrator that will run all night. That’s not a problem from full, but most certainly could be from less than a full charge.
I’ll check the wiring chart on 250 watts, but I don’t think the p- on the BMS is going to be any sort of safety improvement.

Could a Victron Smart Shunt be used to cut off power at a programmed voltage?

 

[mikefitz]

Could a Victron Smart Shunt be used to cut off power at a programmed voltage?

Not on its own, there is no relay output, ( there is on the MBV712). The BMV battery monitor or the Battery Protect, may be useful.

BMV-712 Smart - Victron Energy

Communicate wirelessly between products and simplify system installation and enhance performance using the BMV-712 Smart. Find a dealer now.

www.victronenergy.com

Smart BatteryProtect - Victron Energy

Disconnect the battery from non essential loads before it is completely discharged with Victron Energy's Smart BatteryProtect. Find a dealer near you.

www.victronenergy.com

The Victron Battey Protect cannot be used directly to cut DC power to the inverter ( the fet switches in the battery protect may be damaged) but it could switch a relay. The BMV with its built in low power relay. Either unit could, disable the inverter if a remote switch option exists on the inverter, or via suitable power relays isolate the AC load or the DC connection to the battery. ( the on/off switch on the inverter can be 'hacked' if you have the necessary skills)

The BMV712 has a similar user settable relay but in addition to voltage levels can be programmed for capacity.

An advantage of the MBV over the lower cost Battery Protect, is that its a 'battery fuel gauge' and will help battery management and fully indicate battery volts, current and capacity via the display. ( the Smart Shunt can do all this but lacks the relay output).

There are numerous low cost modules from Amazon or E bay as a low cost alternative. example,
voltage switch
voltage switch 2

The relays on the Ebay units could directly switch off your AC load on the inverter outputs. Whatever solution you adopt some audible or visual warning would seem appropriate.

Mike

 

[pollenface]

You can use an automotive dual battery VSR which will disconnect at 12.8v

 

[Bud Martin]

Does GOWISE inverter have remote on/off terminal that work with simple ON/OF switch? If it does you can use Low Battery shutoff module to turn the GOWISE off via a small relay.
I use this module for Low Voltage Inverter shut off.
It is not a good idea to disconnect the DC input from the battery because every time you reconnect the capacitor banks inside the inverter be charged up and that will high inrush current that can damage Victron BP as explained.

 

[jpimlott]

I did the mod to my inverter for shut off. I use the relay on an epever charge controller for low voltage disconnect.
The relay in the CC goes to a relay with high power contacts for some loads and the remote power switch.
I have a simple switch to turn on the inverter with it.

 

[Mcgivor]

To overcome the same problem, I use a DIN rail voltage monitoring relay which has dry contact output, the inverter toggle switch is wired in series with the NC contact, so in essence it simply turns off the inverter but leaves the battery connected to maintain the capacitors charge. This does however involve opening the inverter, the relay has many programmable features see technical data sheet below, programming includes voltage hysteresis which is useful if large intermittent loads cause nuisance shutdown from voltage sags.

 

[time2roll]

Ok, I have a modest 4s 280ah bank with a dumb Daly 60/30 bms with a ten gauge p-. My inverter is a 600 watt GoWisthat has a lead acid low voltage activation of 10.6 which is way to low.

Have you used this with the O2 concentrator yet? I would give it a go and see if the issue actually presents itself. Going to 10.6 a time to two will not kill the battery.