How to Calibrate Growatt Battery Voltage Offset

[RememberTheMagic]

So I asked Growatt how to calibrate their Growatt Inverter to match the actual voltage read at the battery terminals (to compensate for voltage drop in cable from the battery terminals to the Inverter), they sent me this video. It appears the person doing the video was making mistakes and having to start over several times and was unsure what they were doing. Anyone able to translate this and know what the exact procedure is? In my case the inverter is reading .45 volts lower at the inverter than what is at the battery terminals (due to loses in the terminal connections, battery cable, etc..)

ES Battery Voltage Calibration.MP4

drive.google.com

 

[RCinFLA]

The video appears to just be setting up various parameters in inverter. The only reason for connecting the voltmeter to inverter DC input would be to calibrate what the inverter shows for DC input value.

You can calibrate inverter DC input, but you cannot calibrate inverter to represent battery terminal voltage since there is resistance for battery cabling, circuit breakers, etc. that will have greater voltage drop depending on how much load is put on inverter.

 

[RememberTheMagic]

The video appears to just be setting up various parameters in inverter. The only reason for connecting the voltmeter to inverter DC input would be to calibrate what the inverter shows for DC input value.

You can calibrate inverter DC input, but you cannot calibrate inverter to represent battery terminal voltage since there is resistance for battery cabling, circuit breakers, etc. that will have greater voltage drop depending on how much load is put on inverter.

So how do you compensate for the loss in cables and connectors? For example, I use LifePo4 (very small voltage changes as compared to Lead Acid) and need to have fairly accurate charge/discharge voltages? Now, for example The inverter thinks the battery is low by .45 volts and tries to overcharge the battery.

 

[RCinFLA]

You did not say what type of batteries you are running.

Any battery capacity readout on an inverter based on input DC voltage to inverter is pretty much useless and should be ignored. Get a battery monitor with a current shunt that keeps track of amp-seconds going in and out of battery with voltage sense directly to battery terminals. BMS's that have cell voltage readout usually include the coulomb counting feature which is best way to keep track of % capacity remaining on battery.

Even with a BMS you typically don't have a direct sense connection to the actual cell terminal. You are typically connected to top of bus bars which may have some resistance between battery terminal and top of bus bars. This is a disadvantage and an advantage in that it can give you indication that there might be a particular bus bar connection problem. High current connections are not easy, especially with aluminum terminals that build aluminum oxide coating quickly.

If you are using 12v self-contained batteries in series, then at least put voltage measurements on each 12v battery. Some 12v self-contained LFP batteries have Bluetooth RF connectivity that tell you voltage on each of the four individual cells internal to the battery. It helps indicate if cells are getting out of balance so you can take action of full charging to correct the imbalance. Little battery voltage monitors are cheap and can be wired up to each battery.

 

[RememberTheMagic]

You did not say what type of batteries you are running.

Any battery capacity readout on an inverter based on input DC voltage to inverter is pretty much useless and should be ignored. Get a battery monitor with a current shunt that keeps track of amp-seconds going in and out of battery with voltage sense directly to battery terminals. BMS's that have cell voltage readout usually include the coulomb counting feature which is best way to keep track of % capacity remaining on battery.

Even with a BMS you typically don't have a direct sense connection to the actual cell terminal. You are typically connected to top of bus bars which may have some resistance between battery terminal and top of bus bars. This is a disadvantage and an advantage in that it can give you indication that there might be a particular bus bar connection problem. High current connections are not easy, especially with aluminum terminals that build aluminum oxide coating quickly.

If you are using 12v self-contained batteries in series, then at least put voltage measurements on each 12v battery. Some 12v self-contained LFP batteries have Bluetooth RF connectivity that tell you voltage on each of the four individual cells internal to the battery. It helps indicate if cells are getting out of balance so you can take action of full charging to correct the imbalance. Little battery voltage monitors are cheap and can be wired up to each battery.

So they are 16S 1P 230ah LifePo4 with a Daly BMS. Growatt does NOT support communications with the Daly BMS so I have to rely on what the inverter reads for voltage.

 

[RememberTheMagic]

So I asked Growatt how to calibrate their Growatt Inverter to match the actual voltage read at the battery terminals (to compensate for voltage drop in cable from the battery terminals to the Inverter), they sent me this video. It appears the person doing the video was making mistakes and having to start over several times and was unsure what they were doing. Anyone able to translate this and know what the exact procedure is? In my case the inverter is reading .45 volts lower at the inverter than what is at the battery terminals (due to loses in the terminal connections, battery cable, etc..)

ES Battery Voltage Calibration.MP4

drive.google.com

Thanks to Watts247 I was able to answer this:
How to Adjust or calibrate display values:

1. Press “UP” and “DOWN” at the same time
2. Input password “111” and enter.
3. Scroll through to the parameter that requires calibration. NOTE A prefix is to Add, S Is to subtract the "value" e.g 1.1 in the suffix
4. Exit
5. Shut down and restart the inverter

 

[Cyberbeej]

Thanks to Watts247 I was able to answer this:
How to Adjust or calibrate display values:

1. Press “UP” and “DOWN” at the same time
2. Input password “111” and enter.
3. Scroll through to the parameter that requires calibration. NOTE A prefix is to Add, S Is to subtract the "value" e.g 1.1 in the suffix
4. Exit
5. Shut down and restart the inverter

Glad i found this thread, now managed to get the pair of inverters reading the same battery voltage after a small 0.4v adjustment. Takes a bit of figuring out to get it as it isn't exactly intuitive.
Thanks

 

[derekisastro]

What do the settings 29 to 33 mean? I'm not sure which setting(s) I should be adjusting.

 

[Var]

I have a Growatt SPF 6000T DVM inverter and I'm trying to calibrate the battery voltage to match the voltage at the battery, the voltage is off 1.99v above the battery voltage.
so my problem is that I try holding the up and down key at the same time to reach the pw screen and it just not working for me at all.
I need some help please.