question

strop avatar image

Battery Discharge Protection - Inverter

I have a mobile (Caravan) system that is Lithium based but I DO NOT have Victron Lithium batteries. My batteries also do not have an accessible BMS. They are a Renogy 170 AH lithium batteries.


My system is charged via a Victron 100/50 Smart Solar MPPT and a Victron 30 amp AC charger. I also have fitted a BMV712, smart battery sense and a 65 amp Smart Battery Protect.

I am about to install a NON Victron Inverter 2800/5600 watts to see how much I can do via 240v instead of gas. Induction cooking etc.

my question is about how I best protect my batteries from over discharge whilst using the inverter.

I have read that you should not use a Smart Battery Protect on an inverter. Is this correct?


if you can then the 220 amp model it may be a bit small (2640 watts).

Can I use the BMV712 to activate a relay to disconnect the inverter?


Are there any other alternatives?


Thanks

Battery Protectinverter current draw
2 |3000 characters needed characters left characters exceeded

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

3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The easiest thing would be that you can programing a low voltage cut-off directly at the inverter. Set this to 11V or 11.5V and you should be safe.

OR

If the inverter have a connector for a remote on/off switch (like all Victron inverters) than you can wire this connector to the relay of your BMV-712.

3 comments
2 |3000 characters needed characters left characters exceeded

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

Thanks, that takes care of the inverter, but not the ELV lights, or 12 volt water pump etc.

For other DC loads you can use the Battery Protect.
https://www.victronenergy.com/battery_protect

@Matthias Lange - DE this may be dangerous for your Li bank, my 12V 3kW Phoenix inverter consumes ~ 400mA when in LVP! So that will quite quickly drain the last bits out of your Li bank. The remote on/off switch seems to be a better solution, although that also seems to consume a little bit of energy.

tex260z avatar image
tex260z answered ·

Firstly be aware of the maximum amps discharge limitation of any LiFePO4 battery with built in BMS, I got caught out on that. That is a pretty big inverter. I am running an induction cooktop flat out on a 200 Amp LiFePO4 for more than enough time to cook meals.

Secondly if everything is running through your BMS, that will provide low voltage cutout protection. I bought a Victron BP, but ended up not needing it.

I am still waiting for confirmation that my hookup for everything through my 3 port BMS is correct from others, (see my pictures attached to my last question).

2 |3000 characters needed characters left characters exceeded

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

tex260z avatar image
tex260z answered ·

Firstly be aware of the maximum amps discharge limitation of any LiFePO4 battery with built in BMS, I got caught out on that. That is a pretty big inverter. I am running an induction cooktop flat out on a 200 Amp LiFePO4 for more than enough time to cook meals.

Secondly if everything is running through your BMS, that will provide low voltage cutout protection. I bought a Victron BP, but ended up not needing it.

I am still waiting for confirmation that my hookup for everything through my 3 port BMS is correct from others, (see my pictures attached to my last question).

2 |3000 characters needed characters left characters exceeded

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