Hi there

We currently have 2 of your Growatt spf5000es inverters on our property

and I have a question regarding the SOC and some strange behavior.

Our installer can't seem to answer these questions so I thought I would reach out to you.

Our SOC reads 100% all night long but at about 5:30 am when the sun comes up it drops down to 25%.

Is there something wrong with the system? 

IS this normal? Is there another way to determine how much charge we have on our batteries? 

Any help or information regarding this would be greatly appreciated.

What battery do you have? are your comms connected between battery and inverters? Growatt only measures battery voltage.

It's normal for lead acid batteries which I initially had. Then when I got lithiums I had the bms cable connected and it gives accurate battery percentage.

I would not know how lithiums behave without the bms cable.

2 minutes ago, Buyeye said:

It's normal for lead acid batteries which I initially had. Then when I got lithiums I had the bms cable connected and it gives accurate battery percentage.

I would not know how lithiums behave without the bms cable.

Been running my system for 18 months without BMS comms, my settings are on USE and the charge and floating voltages settings as per battery OEM so far, no problems. My battery gets to 99% SOC every day. see atached dashboard. 

8 minutes ago, Antonio de Sa said:

Been running my system for 18 months without BMS comms, my settings are on USE and the charge and floating voltages settings as per battery OEM so far, no problems. My battery gets to 99% SOC every day. see atached dashboard. 

Then is it safe to assume he has lead acid batteries?

27 minutes ago, Antonio de Sa said:

My battery gets to 99% SOC every day. see atached dashboard.

Slow down there, just clarify, is this data shown, provided by the BMS to your computer or reported by the inverter to your computer? I suspect the BMS and the inverter doesn't know the accurate or real SOC, but will happily be wrong... if it is from the inverter, how is it getting such fairly accurate (I presume) data without BMS comms...?

Edited February 7, 20233 yr by Kalahari Meerkat
grammatik...

18 minutes ago, Buyeye said:

Then is it safe to assume he has lead acid batteries?

Not sure what battery he uses, I've asked, but so far, no answer from him, in my case is a lithium battery 5.1KW/H

4 minutes ago, Kalahari Meerkat said:

Slow down there, just clarify, is this data shown, provided by the BMS to your computer or reported by the inverter to your computer? I suspect the BMS and the inverter doesn't know the accurate or real SOC, but will happily be wrong... if it is from the inverter, how is it getting such fairly accurate (I presume) data without BMS comms...?

I forgot he has custom software,  he has been using it so long he also forgot.

3 minutes ago, Kalahari Meerkat said:

Slow down there, just clarify, is this data shown, provided by the BMS to your computer or reported by the inverter to your computer? I suspect the BMS and the inverter doesn't know the accurate or real SOC, but will happily be wrong... if it is from the inverter, how is it getting such fairly accurate (I presume) data without BMS comms...?

@Kalahari Meerkat, what you see is pulled from the Battery Seplos BMS using Modbus protocol, I know I have a cell that is not getting to full charge. check dashboard.

 

@Antonio de Sa & @Buyeye, ok so @Jacques Jambo can't expect the same fancy fairly accurate battery SOC reporting...

if the battery is used based on Voltage setting then the SOC is pretty much useless if its a Lithium type battery, if its a lead acid affair, then the SOC should be easier to work out based on Voltage, but how are these made up 24 x 2V cells? 4 x 12V batteries? if so any balancers between them? Either way @Jacques Jambo you need to enlighten us on what the battery is, chemistry wise and make model and how it is put together to work with the inverter... does it have a BMS comms cable (assuming lithium) etc. ? I don't know your type of inverter, but the other chaps do... so they can probably make good suggestions, but only if they know what they are dealing with on your end...

Hi Thanks so much for the reply's.

I am seeing the electrician that installed the system in the next day or so and I will try get whatever information I can from him about the batteries. Im assuming we have all lithium ion batteries (10 of them) but thats all the information I have so far.

Will chime back in as soon as possible.

Thanks again for all the help it is really appreciated.

 

It looks like we have 8 x 100ah Huawei (not sure of the model) Lithium batteries and 1 x 200ah duratron 48dpfc200 lithium battery.

Im not sure about the comms connections.

Thats all the information I have so far

Edited February 8, 20233 yr by Jacques Jambo

The initial post in this thread reflects the battery SOC as reported via the inverter. Unfortunately without a data connection to the BMS, the SOC will be limited to 10,25, 50,75 or 100%.
With LA batteries which I had for a very short while, any significant load will drop the Inverter battery SOC from 100% to 25% within seconds. Once the load drops that will then recover to 75%.
Even if you have Li batteries and no BMS comms exist, you will only ever see these "estimated" SOC values, i.e. closest 25% unless it drops below 25% estimate when it will show 10%.
The Inverter has no idea what the real state of your batteries are, it only takes the voltages set as bulk and float and cut off and compares those to the voltage in the battery to calculate a virtual percentage and displays that to the nearest lower 25% scale.

Edited February 8, 20233 yr by zsde