I have a new set of Growatt SPF 3000TL LVM-ES inverters in split phase that I am setting up, and one of them reads 0.5v low for the battery reading. I think this is too far off for proper battery management for LifePo4 batteries. Any suggestions? I bought the inverters from Watts247.
Growatt SPF 3000TL LVM-ES off by 0.5v on battery
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timselectric
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If you are saying that one Growatt is lower than the other.
Then there's a different in resistance between the two.
Could be due to different length, or size cables. Or maybe a slightly less conductive connection.
If you are saying that the Growatt is different from the BMS. That's just voltage drop, and completely normal.
Then there's a different in resistance between the two.
Could be due to different length, or size cables. Or maybe a slightly less conductive connection.
If you are saying that the Growatt is different from the BMS. That's just voltage drop, and completely normal.
The battery voltage reading on the display is 0.5v low on one of them, meaning it thinks the batteries are 0.5v lower than they actually are. Voltage has been measured with a meter at both units to confirm one is reading low compared to what the voltage actually is.
I would just like to add that there is no integrated BMS. I have sets of batteries in series/parallel (with balancers). So for charging and discharging the Growatt units are in control. So I am concerned that being off that much will be an issue.
timselectric
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I wouldn't worry about 0.5v
But you can always adjust your charging settings by 0.5v if it concerns you.
But you can always adjust your charging settings by 0.5v if it concerns you.
timselectric
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Just to clarify:
In a 48v system.
Yes, I know it is only about a 1% difference in voltage readings (which I do feel is NOT acceptable by today's standards), but with LifePo4 batteries there are voltage ranges that could mean a 20-30% difference in charge capacity, which could affect my settings, especially with 2 units synced together for split phase. I hate to have to remember to have one unit off by 0.5v to make things match. (SIGH) cheap Chinese crap at its best...
timselectric
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They don't have to be set differently. Unless it just makes you feel better.
It won't make any difference, either way.
timselectric
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These are mine. And it's not a problem.
I am not sure we are talking about the same thing. All of my batteries will be on the same circuit, and the only management will be the inverters with the battery mode set as user, so there will not be any individual battery bank voltage. My issue is with the inverter readings. I am worried that the difference in inverter battery voltage will cause one inverter to act different than the other when set at the same settings (don't know how that works when the inverters are communicating with each other in split phase). I am also concerned that the inverter that reads .5v low would want to charge the batteries .5v higher. I know that the batteries themselves have their own cutoffs, so I guess that should not be an issue. But I really don't want one inverter kicking in and out of solar/battery/utility different than the other.
timselectric
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Mine are stacked, and connected to one battery bank.
They all share the same settings and work together fine.
The sync cables won't let that happen. They operate as a single system.
I asked here first before doing research thinking that someone would point me in the right direction quickly. Now that I had time to search and found an actual answer on how to calibrate the voltage, why didn't anyone point me to this?
diysolarforum.com
It took a few tries because that link lacks details, but now I have it reading correctly 
How to Calibrate Growatt Battery Voltage Offset
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...
diysolarforum.com
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I emailed Watts247 and they sent me this link which contains the same information as the post referenced above.
I am very happy there is a way to calibrate the voltages if needed.
I am very happy there is a way to calibrate the voltages if needed.
timselectric
If I can do it, you can do it.
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Glad that you found a solution.
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