Growatt 5000 ES - Low Voltage Cut Off Warning

[Olasitu]

Hello all,

I have 2 x Growatt 5000 ES as part of my Set up.

The Inverters have shut down with NO warning 3 times in the last month. The batteries - not BMS enabled – appear to have shutdown to protect low voltage. They were displaying 51.3 V.

My Low Voltage Cut off is however set at 48V which means the batteries will shut down before the Inverter cuts-off. All makes sense.

Questions:

• What is an appropriate Low Voltage Cut Off setting that will provide adequate warning but still let you maximize battery capacity. Assuming now that the batteries will shut down at ~51.4V.
• Will the warning kick off before Low Voltage is reached if so, how is that determined?

Just FYI - I have 2 Growatt 5000 ES installed in Parallel with 2 x Blue Carbon 48V 200Ah Lithium Battery Pack for Solar Home System. PVs are Mono 10 x 550W. 5 panels each in series to each Inverter. Priority is set to Solar, Utility and Battery.

 

[tabascoz]

Hi there. I don't know these batteries myself but i google it and they seem to have BMS. What do you mean by "not BMS enabled"?

I have 3x Growatt 5000es and 2X DIY battery banks 48v280ah. I have cell low voltage protection set on the BMS to shutdown if any battery go below 2.6 and a warning when they go below 2.8.

Growatt low voltage batt protection it does exactly the way you describe, It shuts down without warning if battery goes under the threshold.

• What is an appropriate Low Voltage Cut Off setting that will provide adequate warning but still let you maximize battery capacity. Assuming now that the batteries will shut down at ~51.4V.

I think to BMS level the cell protection (being conservative) at 2.8 is a good setting. note when SOC is low and if you draw tons of load the cell v could go momentarly below this level so you need to balance it according to your needs. As i have 560ah of total capacity, for my needs it is not a problem. Staying with this value, then Growatt absolute minimum shoul be around 44.8v ( 2.8*16). 3v (48 total) is way too conservative, but won't prevent you from using the battery to the most given 90% of the SOC capacity should be above 3v.

Will the warning kick off before Low Voltage is reached if so, how is that determined?

In theory if you connect the battery BMS to Growatt and it works fine, then Growatt will start reading the SOC and will do a cutoff based also on battery SOC and not only by the voltage, which is way better.

I don't think though it beeps or does anything... it alos shuts off when SOC is below the setpoint ( minimum is 5% cutoff, 10% if there's available mains voltage) but I'm not sure as all my alarms are disabled and i monitor the inverters throguth Homeassistant and set some alarms and automation to help me with battery utilization.

 

[timselectric]

The Inverters have shut down with NO warning 3 times in the last month. The batteries - not BMS enabled – appear to have shutdown to protect low voltage.

The BMS is what is shutting down the battery. So, they do have BMS's.

My Low Voltage Cut off is however set at 48V which means the batteries will shut down before the Inverter cuts-off. All makes sense.

That's backwards.
The inverter should shutdown before the BMS.
The BMS is the last level of protection. It shouldn't be used in normal operation. Only as a last resort.

What is an appropriate Low Voltage Cut Off setting that will provide adequate warning but still let you maximize battery capacity.

It depends on how much reserve you want to keep.
I stop draining my battery bank at 48v. But I have a large bank and this still gives me plenty of reserve. My BMS cutoff is set at the first cell to drop to 2.5v.

Will the warning kick off before Low Voltage is reached if so, how is that determined?

If the battery dips below the cutoff setting briefly, an alarm will sound. (If alarms are set to on)
If it remains below the setting, or dips deeply, it will shutdown.