Battery SOC Behaviour with Growatt SPF 5000ES

[AshleyL]

This sounds a lot like what is happening to me. I am using a Growatt SPF6000T with a Rosen 10kw 200AH 15S battery. I was using the Lithium setting and connecting the battery via CAN L52 but the inverter would switch back to the grid relatively quickly and when I checked the SOC on the battery it was usually very high, sometimes over 80%. Since then I've tried using US2 and USE with limited success. I have had a lot of code 03(low voltage) and code 04(over voltage) errors. When I get the over voltage errors the BMS(I assume) disconnects the panels from the battery, presumably to stop it from overcharging and this cycle just keeps repeating itself until I turn it off. I fixed the overcharging issue by reducing the voltage in setting 19 to 52.5v/3.5v per cell. I still don't understand why it switches back to grid when the battery is almost full.

3.5V per cell is about the right voltage. No point going higher.
Based on your model manual https://i1solar.com/wp-content/uploads/2021/07/Rosen-48V-200AH-Powerwall-Lithium-Battery.pdf

code 03 : 2.7±0.02V about 2.9v?

code 04 : 3.65±0.025V about 3.5v?

Standard discharge/charging is 20A....meaning 48v x 20A= 960watts.
You sure you didn't utilize more than 20A? Some lower quality battery has serious voltage sag when a heavy drain is demanded.
Some so called B-grade EVE 280AH battery voltage sag seriously under 40A drains.

EVE 280K LiFePO4 Cells from QSO/Shenzhen Qishou Technology

... Woooosahhhhhh. My Apologizes, I did not read that, Nightguest I'll await your posting of the qr code.

diysolarforum.com

I quote:

Based on this I do not recommend QSO to people who are not experienced in testing individual cells using 40 amps - and more.
The reason is that a higher discharge rate may not sustain the nominal (3.2) voltage. For example, if you make a 16S battery from cells like this, and you've NOT verified that they can hold the discharge rate, you may get a low voltage disconnect even if your pack is technically at 100%. It is not uncommon for B cells to drop to 3.0 or below, under high C discharge.

Perhaps this is what you faced?

 

[Philectric246]

3.5V per cell is about the right voltage. No point going higher.
Based on your model manual https://i1solar.com/wp-content/uploads/2021/07/Rosen-48V-200AH-Powerwall-Lithium-Battery.pdf

code 03 : 2.7±0.02V about 2.9v?

code 04 : 3.65±0.025V about 3.5v?

Standard discharge/charging is 20A....meaning 48v x 20A= 960watts.
You sure you didn't utilize more than 20A? Some lower quality battery has serious voltage sag when a heavy drain is demanded.
Some so called B-grade EVE 280AH battery voltage sag seriously under 40A drains.

EVE 280K LiFePO4 Cells from QSO/Shenzhen Qishou Technology

... Woooosahhhhhh. My Apologizes, I did not read that, Nightguest I'll await your posting of the qr code.

diysolarforum.com

I quote:

Perhaps this is what you faced?

 

[Philectric246]

Thanks for the insight, I might very well be drawing more than 20A. What is the best way to check the current draw? There is an indicator on the battery which tells you how much current is being discharged, I will have to pay more attention to it. Is there a way to tell if the cells in your battery are grade A or grade B? Would increasing the amount of battery to 20kw help? I will be getting some other batteries to try soon, hopefully they won't have the same problem, the seller said that they have grade A CATL cells. I got a user manual with my battery but it is different to the one that you have, it does not have in the BMS protection parameters.

 

[AshleyL]

Thanks for the insight, I might very well be drawing more than 20A. What is the best way to check the current draw? There is an indicator on the battery which tells you how much current is being discharged, I will have to pay more attention to it. Is there a way to tell if the cells in your battery are grade A or grade B? Would increasing the amount of battery to 20kw help? I will be getting some other batteries to try soon, hopefully they won't have the same problem, the seller said that they have grade A CATL cells. I got a user manual with my battery but it is different to the one that you have, it does not have in the BMS protection parameters

How much trust you have on the seller? Always be skeptical.
Anyway, it is impossible for Lifepo4 not to have BMS protection.
Try to pay special attention to your battery pack discharge current. I don't trust the discharge curve in the manual either because you don't know if they still use the same "good" cells. As with every production, it is normal for manufacturer to "substitute" components for "cost optimization"/"profit maximization" purpose.......

As for your question to know the battery grade......there is no grade A or B. There is only two types : Qualified cell that can be used for electric vehicle and Rejected cell that failed to meet the EV requirement. Majority cells in the market is....REJECTED type.

One of EV main requirement is ability to handle a large current surge and the voltage cannot simply sag very low until it triggers BMS LVD disconnect. This one requirement says a lot about rejected cell......

 

[Philectric246]

I was watching the battery when the microwave came on and the draw was over 30 Amps. When I first got the battery, before my loads were balanced, the microwave used to often cause overload faults and shut down the inverter. 960watts doesn't sound like a lot, if I had double the battery would I be able to draw half of the power from each battery and keep them from going over that 20A discharge threshold?

I have managed to get rid of the errors/fault codes by adjusting the voltage as advised by members of this forum. My inverter is working very well during the day but at night a little while after I start using the battery, even if no extra loads are on, after a little while the lights start to flicker. It stops if I turn the inverter back to utility, so I'm thinking it is probaby a problem with the battery.

Final question, don't EVs use Lithium-ion batteries? My battery is LifePO4.

 

[AshleyL]

I was watching the battery when the microwave came on and the draw was over 30 Amps. When I first got the battery, before my loads were balanced, the microwave used to often cause overload faults and shut down the inverter. 960watts doesn't sound like a lot, if I had double the battery would I be able to draw half of the power from each battery and keep them from going over that 20A discharge threshold?

I have managed to get rid of the errors/fault codes by adjusting the voltage as advised by members of this forum. My inverter is working very well during the day but at night a little while after I start using the battery, even if no extra loads are on, after a little while the lights start to flicker. It stops if I turn the inverter back to utility, so I'm thinking it is probaby a problem with the battery.

Final question, don't EVs use Lithium-ion batteries? My battery is LifePO4.

For the last question, the latest EV model is using Lifepo4 replacing the older lithium ion.

Flickering LED = Give it up or buy better LED lamp? The flickering is caused by large inductive load such as air-conditioner/refrigerator especially inverter type compressor.

Doubling the battery? Not sure how your battery pack is wired to your inverter. In parallel or series?
Can your inverter/wires handle higher amperage rating?
How will the multiple battery pack communicate to each other....and with the inverter as well?

Multiple battery packs = you gonna encounter balancing issue.

 

[Philectric246]

ok, I am not sure how to tell if one LED lamp is better than the other. Just trial and error?

When you say inverter wires, you mean the wiring inside the inverter or the output wires from the inverter. I am usiing #4 wire to and from the inverter.

Right now I only have one battery, so it's not parallel or series. I am probably not understanding this question.

The batteries usually come with communication cables to connect to each other and there is usually one from the inverter to the first battery.

Thanks

 

[AshleyL]

ok, I am not sure how to tell if one LED lamp is better than the other. Just trial and error?

When you say inverter wires, you mean the wiring inside the inverter or the output wires from the inverter. I am usiing #4 wire to and from the inverter.

Right now I only have one battery, so it's not parallel or series. I am probably not understanding this question.

The batteries usually come with communication cables to connect to each other and there is usually one from the inverter to the first battery.

Thanks

LED part = buy Philip Ultra Efficient range, I bought 8 bulbs and none of them flickers. I retired my Panasonic LED bulb due to serious flickering whenever I turn on my air conditioner.

As for the wiring part, you need to consult with expert.

 

[Philectric246]

LED part = buy Philip Ultra Efficient range, I bought 8 bulbs and none of them flickers. I retired my Panasonic LED bulb due to serious flickering whenever I turn on my air conditioner.

As for the wiring part, you need to consult with expert.

Thanks