nelsonjrgomes
New Member
Hi,
I have a Growatt SPH 3000 hybrid installed for a bit over one year, and I have added, a couple months ago, 2 server rack batteries (2x100 Ah 48v) that I bought from Aliexpress. The BMS communicates with my inverter (if I select lead acid battery I have some control over voltage; if I select lifepo4, all the management is done thought the readings of the BMS, and I can't input max SOC percentage or max voltage charge).
I have a problem that I have no idea how to solve - when the batteries are depleted (i.e., SOC percentage below the number I have set in), and the inverter should be in stand by, the inverter is constantly deploying a residual charge current to the batteries. I estimate this charge current is around 1 A - this may not sound like much, but in winter, if I get three days of heavily cloudy days, the batteries will have charged a few kWh from the grid, when they should be in stand by mode. As this residual current is lower than 1 A per battery, the BMS doesn't detect it - so, it totally messes the SOC percentage that the BMS communicates to the inverter . Today, I had a bit over 3,3 V per cell, with the BMS stating a 10% SOC (it had stopped at 10%, but it had around 3 days of slowly charging). I can see that there is an efective charge of the cells, as the voltage is slowly rising over the days. I must add that I have a Shelly EM monitoring the current that is coming from my inverter to the grid, and the other way around - If I disconnect the batteries from the inverter, it draws around 10 W from the grid in stand by; if the batteries are connected, but SOC lower than the defined, the inverter is drawing around 60 to 70 W - and the difference is going to the batteries.
This has a very unpleasant consequence - when, in a few days, the PV power is enough to start charging the batteries, the BMS will tell inverter to charge the batteries - and it will trigger BMS OV protection, as the batteries have a real charge of around 70%-80% (3,3V per cell), but the BMS is telling the inverter the SOC is lower. Obviously, I don't want the BMS to act in a daily basis, stopping charge when it should be the inverter doing that
Any ideas? What is there to be done? I have a feeling, if I contact Growatt support, they'll say that the batteries are not supported, so won't really try to solve anything...
Thanks in advance, and sorry for my poor English.
I have a Growatt SPH 3000 hybrid installed for a bit over one year, and I have added, a couple months ago, 2 server rack batteries (2x100 Ah 48v) that I bought from Aliexpress. The BMS communicates with my inverter (if I select lead acid battery I have some control over voltage; if I select lifepo4, all the management is done thought the readings of the BMS, and I can't input max SOC percentage or max voltage charge).
I have a problem that I have no idea how to solve - when the batteries are depleted (i.e., SOC percentage below the number I have set in), and the inverter should be in stand by, the inverter is constantly deploying a residual charge current to the batteries. I estimate this charge current is around 1 A - this may not sound like much, but in winter, if I get three days of heavily cloudy days, the batteries will have charged a few kWh from the grid, when they should be in stand by mode. As this residual current is lower than 1 A per battery, the BMS doesn't detect it - so, it totally messes the SOC percentage that the BMS communicates to the inverter . Today, I had a bit over 3,3 V per cell, with the BMS stating a 10% SOC (it had stopped at 10%, but it had around 3 days of slowly charging). I can see that there is an efective charge of the cells, as the voltage is slowly rising over the days. I must add that I have a Shelly EM monitoring the current that is coming from my inverter to the grid, and the other way around - If I disconnect the batteries from the inverter, it draws around 10 W from the grid in stand by; if the batteries are connected, but SOC lower than the defined, the inverter is drawing around 60 to 70 W - and the difference is going to the batteries.
This has a very unpleasant consequence - when, in a few days, the PV power is enough to start charging the batteries, the BMS will tell inverter to charge the batteries - and it will trigger BMS OV protection, as the batteries have a real charge of around 70%-80% (3,3V per cell), but the BMS is telling the inverter the SOC is lower. Obviously, I don't want the BMS to act in a daily basis, stopping charge when it should be the inverter doing that
Any ideas? What is there to be done? I have a feeling, if I contact Growatt support, they'll say that the batteries are not supported, so won't really try to solve anything...
Thanks in advance, and sorry for my poor English.
