Light24bulbs
New Member
- Joined
- May 29, 2020
- Messages
- 4
So far, the charging behavior of my growatt 3000 LVM and my lifepo4 batteries has been insane, particularly in utility priority mode.
In utility, what happens is the growatt will charge the batteries from utility (and solar) until they reach a voltage that is pretty far under the charging voltage I set (27.4), then it decides to stop charging entirely and it lets the batteries fall all the way to the low voltage setting before starting a charge again. Maybe this would be ok in a world where I only had AC loads so the battery would never be drawn down when in utility mode, idk, I've given up on trying to understand the logic of Chinese firmware.
In solar priority mode, it's a little better. It at least seems to not turn solar charging OFF during the most productive part of the day. So that's better. At night, it will bring on utility charging, charge the batteries to somewhere close to full but not all the way, and then shut down again and let the DC loads drain the batteries.
This is all just mayhem. The behavior I actually want is extremely simple:
I want to set a utility charging target voltage and a solar charging target voltage. I will set the solar higher than the utility, so that if the battery hits around 50% SOC, the utility will just sit there and not let it go down another .1v. I don't want all of this fluctuation for no reason. It's awful for the batteries, and it leaves me in a random state of charge in the event of a power outage. Is the MPP unit better?
Will finding a BMS with communication (my current ant BMS has no CAN/RS485) help make the behavior less insane? I've noticed that the detected SOC of the growatt is using an absurdly bad algorithm, and most of the time it just sits at 100% or jumps down to 75% for a bit. Trying to figure out what BMS (or better yet just a shunt because I like my current BMS) will actually communicate with the growatt is really difficult. The Chinese companies seem to have failed to come up with anything like a communication standard, instead sticking to walled gardens. Growatt just sent me a big document mostly in Chinese that has the signal protocols they use. Like, fine, you expect me to write a microcontroller to set all these serial bits so I can get your thing to work? What's so hard about coming up with a standard and giving it a name. Anyway can anyone recommend something that will work? There are plenty of things with "rs485" but since there's no standard of implementation, that doesn't get me far. Ideally I'd just have a monitor because my current BMS is fine.
This JK BMS supports both CAN or RS485 if you buy the cable/chip to go with it. Will either of those protocols work with the growatt?
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This super inexpensive shunt supports rs485 and would be ideal because I like my current BMS,
Would that work? I doubt it. Would a Victron smart shunt work? Overpriced as heck.
I've seen people recommend the lephos BMS or whatever as something that works with growatt but it's really really overpriced.
This is all a pretty unimpressive mess software wise, which I guess I should have expected. I'm considering returning this thing for the MPP instead, if it has better firmware.
In utility, what happens is the growatt will charge the batteries from utility (and solar) until they reach a voltage that is pretty far under the charging voltage I set (27.4), then it decides to stop charging entirely and it lets the batteries fall all the way to the low voltage setting before starting a charge again. Maybe this would be ok in a world where I only had AC loads so the battery would never be drawn down when in utility mode, idk, I've given up on trying to understand the logic of Chinese firmware.
In solar priority mode, it's a little better. It at least seems to not turn solar charging OFF during the most productive part of the day. So that's better. At night, it will bring on utility charging, charge the batteries to somewhere close to full but not all the way, and then shut down again and let the DC loads drain the batteries.
This is all just mayhem. The behavior I actually want is extremely simple:
I want to set a utility charging target voltage and a solar charging target voltage. I will set the solar higher than the utility, so that if the battery hits around 50% SOC, the utility will just sit there and not let it go down another .1v. I don't want all of this fluctuation for no reason. It's awful for the batteries, and it leaves me in a random state of charge in the event of a power outage. Is the MPP unit better?
Will finding a BMS with communication (my current ant BMS has no CAN/RS485) help make the behavior less insane? I've noticed that the detected SOC of the growatt is using an absurdly bad algorithm, and most of the time it just sits at 100% or jumps down to 75% for a bit. Trying to figure out what BMS (or better yet just a shunt because I like my current BMS) will actually communicate with the growatt is really difficult. The Chinese companies seem to have failed to come up with anything like a communication standard, instead sticking to walled gardens. Growatt just sent me a big document mostly in Chinese that has the signal protocols they use. Like, fine, you expect me to write a microcontroller to set all these serial bits so I can get your thing to work? What's so hard about coming up with a standard and giving it a name. Anyway can anyone recommend something that will work? There are plenty of things with "rs485" but since there's no standard of implementation, that doesn't get me far. Ideally I'd just have a monitor because my current BMS is fine.
This JK BMS supports both CAN or RS485 if you buy the cable/chip to go with it. Will either of those protocols work with the growatt?
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a.aliexpress.com
This super inexpensive shunt supports rs485 and would be ideal because I like my current BMS,
Would that work? I doubt it. Would a Victron smart shunt work? Overpriced as heck.
I've seen people recommend the lephos BMS or whatever as something that works with growatt but it's really really overpriced.
This is all a pretty unimpressive mess software wise, which I guess I should have expected. I'm considering returning this thing for the MPP instead, if it has better firmware.
