pylontech us3000c discharge from 53.2 v to 49.8 v in 2 minutes with 300w load .. then back to grid .. mode SBU .can someone help me ? thanks

53.2V seems very high for a 15S battery. Are you running the inverter on user settings or with BMS comms?

Here's an excerpt from the victron website... they generally seem to know what they are talking about:

"When DVCC is enabled, the battery (via the CAN-bms) is responsible for the charge voltage. The Pylontech battery requests a charge voltage of 53.2V. We have however found that in practice this is too high. The Pylontech battery has 15 cells in series, so 53.2V equates to 3.55V per cell. This is very highly charged and makes the system prone to go overvoltage.

It should also be noted that a LiFePO4 cell stores very little additional energy above 3.45V. For this reason we opted to override the BMS and cap the voltage at 52.4V. This sacrifices almost none of the capacity and greatly improves the stability of the system."

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

Also, what are the SOC lights on the battery showing when this happens? If they still show it is highly charged then perhaps you need to drop your back to grid voltage, the internet tells me the US3000C can go as low as 45V.

I use PYL Settings with bms comunication. I put 51v max charging for battery and 48v back to Grid .But the inverter still Charge until 53.2 v .and the SOC light are steady, and Show that the battery îs full ...thanks

Edited December 22, 20222 yr by Adriandanut

With the PYL setting it will be ignoring what charge voltage you set, it will keep overriding it that's why it goes to 53.2V.

Strange that the inverter goes to grid at 49.8V when it is set to 48V, perhaps the voltage is sagging under the load, but that is not a big load. I have read that 1 pylontech battery is usually not enough on its own as they don't like high discharge current.

For reference I have a 16S battery which settles to 53V after charging, so I would expect a 15S battery to settle to 50V or just below which is basically 49.8V, so 48V BtG doesn't give you much room. I would lower the BtG to 46.5V (leave room for LS) and see how it goes. You should be able to judge from the SOC lights how low the battery is actually going and adjust according to that. The best would be to set up a cable to the console port and connect with a PC to see exactly what the battery is doing.

1 hour ago, jumper said:

53.2V seems very high for a 15S battery. Are you running the inverter on user settings or with BMS comms?

Here's an excerpt from the victron website... they generally seem to know what they are talking about:

"When DVCC is enabled, the battery (via the CAN-bms) is responsible for the charge voltage. The Pylontech battery requests a charge voltage of 53.2V. We have however found that in practice this is too high. The Pylontech battery has 15 cells in series, so 53.2V equates to 3.55V per cell. This is very highly charged and makes the system prone to go overvoltage.

It should also be noted that a LiFePO4 cell stores very little additional energy above 3.45V. For this reason we opted to override the BMS and cap the voltage at 52.4V. This sacrifices almost none of the capacity and greatly improves the stability of the system."

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

Also, what are the SOC lights on the battery showing when this happens? If they still show it is highly charged then perhaps you need to drop your back to grid voltage, the internet tells me the US3000C can go as low as 45V.

Ok . So you Say to change PYL with USER mode and to set 51v max charging and BTG 46.5 ? To SEE what happens , isn’t ? Thank you

1 minute ago, Adriandanut said:

Ok . So you Say to change PYL with USER mode and to set 51v max charging and BTG 46.5 ? To SEE what happens , isn’t ? Thank you

You can leave the cable in and just change the BtG or you can take it out and use the USE setting, but then change the charge voltage to 52.4V. I have read that no BMS to  inverter comms might affect the pylontech warranty, so I would just leave the cable in first and just drop the BtG to 46.5V and check the SOC lights intermittently to see how it is doing.

With user mode  and 52v max charging ( i cant set 52.4) and BTG 46v still Charge until 53.2 v .. But Now isn’t switching back to battery with this Settings .

1 hour ago, Adriandanut said:

With user mode  and 52v max charging ( i cant set 52.4) and BTG 46v still Charge until 53.2 v .. But Now isn’t switching back to battery with this Settings .

Normally, with a communication cable plugged in, the inverter will use the settings sent by the BMS and that will overrule any manual settings.

53,2v is the normal setting the Pylontech bms sends.

I Take Off the Cable .. still charging to 53.2 .it doesen’t stop to 52v .. and When he reach 53.2 It dosen’t switch to battery back … User mode and Cable take Off ..

I would leave the communication cable in. The pylon is ok at 53.2v. The voltage drop in your first post is also OK. You need to look at the inverter to see why it is stopping after a couple of minutes. The battery should be able to do 37A max current. When the inverter stops discarging from the battery are the battery led's all ok?

The leds are ok and full when he stopa from discharging ,and the load from the house îs about 300-350 w.

It really sounds as if their is an incorrect setting in the inverter.

I check all the Settings …many Times …i don’t know what Could be …the inverter is an Easun smw 8kw ..

10 hours ago, Adriandanut said:

I Take Off the Cable .. still charging to 53.2 .it doesen’t stop to 52v .. and When he reach 53.2 It dosen’t switch to battery back … User mode and Cable take Off ..

If your battery is full which it sounds like from the SOC lights then the inverter will probably overshoot the voltage, it will probably stop around only 52V when you are charging up from a lower SOC.

The settings that control the inverter switching from between battery and grid are: Back to Grid and then Back to Battery. What is Back to Battery set to? I would try 52V.

Hopefully someone with some pylontechs can comment with their settings.

I think the inverter is to blame .. it's an Easun smw 8kw .. and from what I've read on other forums it would be an Axpert clone or something like that .. and it might not be that successful . thanks anyway for the answers  .. I tried all the options .. and at 52v max charging and at 51v and still nothing...

Just make sure that your Back to Battery setting is lower than the max charge or it probably won't switch to battery. Maybe try 50V to test.

Also maybe turn of the AC IN to the inverter to see if it will run from battery alone. If there is no grid then it will ignore the BtG and BtB settings and should run until the cutoff voltage.

6 hours ago, jumper said:

If your battery is full which it sounds like from the SOC lights then the inverter will probably overshoot the voltage, it will probably stop around only 52V when you are charging up from a lower SOC.

Hopefully someone with some pylontechs can comment with their settings.

The inverter should never exceed its set voltage no matter what SOC.

I don't see this as a Pylontech problem. For manual setting  45.5v is the minimum Pylontech recommend as the lower cut off voltage. 52.5v to 53.2v for max charge voltage. Personally I would always use CAN communication, it provides more safeguards.

 

5 minutes ago, Tinbum said:

The inverter should never exceed its set voltage no matter what SOC.

I guess you've never owned an axpert, they tend to overshoot, especially when the battery is fully charged and it starts a charge cycle, it will overshoot quite a bit before it realizes and reels itself in.

I also don't think this is a pylontech problem which is why I was hoping someone with pylons could comment on the voltages because that affects the back to grid and back to battery settings.

1 hour ago, jumper said:

I guess you've never owned an axpert, they tend to overshoot, especially when the battery is fully charged and it starts a charge cycle, it will overshoot quite a bit before it realizes and reels itself in.

 

No, I've not and wouldn't touch it with a barge pole if it does that.

 

With Pylontech anything over 55v will damage its BMS.

5 hours ago, jumper said:

Just make sure that your Back to Battery setting is lower than the max charge or it probably won't switch to battery. Maybe try 50V to test.

Also maybe turn of the AC IN to the inverter to see if it will run from battery alone. If there is no grid then it will ignore the BtG and BtB settings and should run until the cutoff voltage.

If i turn Off the grid Works works very good until the cut Off Voltage.

15 hours ago, Adriandanut said:

If i turn Off the grid Works works very good until the cut Off Voltage.

That sounds like some sort of inverter settings conflict there that is causing it to not want to use the battery while there is grid. The battery seems fine.

I would plug the comms cable back in and change to the PYL setting to see how it runs now that the battery has been discharged.