Hello everyone 

I have a 5kw Deye inverter with 1 US3000 pylon tech battery. Why does my inverter show error F56 and my power shuts down for 1 min the goes on like normal. The battery show 98%. Can anyone the assist.

thanks

F56 is a DC Busbar low voltage error. As per Sunsynk training manual:
 

Quote

 

F56 - DC busbar voltage is too low
Generally, this error is a battery problem, possibly a damaged BMS. If you experience an F56 fault, you need to focus on the battery, the battery cables, the battery connections, battery discharging parameters, and the general condition of the battery.
1) Check if battery cables are nice and tight.

2) If using a parallel configuration, check if all battery cables have the same length. As the batteries are low voltage compared to the mains, the current is high, so check the cable size and notice if they have the same length.
3) Check the C rating of the battery.
4) Check the maximum current discharge setting of the inverter.
5) Check the maximum power setting (Max sell Power) of the inverter

 

My money is on the max discharge rate incorrectly set, one Pylontech US3000 won't deliver more than 37A. What was your essential load's AC current drain at the time? Did it exceed 1776W?  
 

21 hours ago, Bobs said:

Hello everyone 

I have a 5kw Deye inverter with 1 US3000 pylon tech battery. Why does my inverter show error F56 and my power shuts down for 1 min the goes on like normal. The battery show 98%. Can anyone the assist.

thanks

Hi Bob. It's possible that your essential load was more than 1700w and at that instant the grid shut down. It's an issue with these 0.5C batteries. 

Your installer should have briefed you on the limitations of the system. 

Regards

dear sir i install 12kw 3 phase inverter with one pack of battery ( 24 battery * 2 volt each * 1380 AH EACH ) and usual the common fault is f56 can you please help me 

Hi everyone, I was seeing the same F56 error on our 5kW Deye Inverter. I solved the problem by adjusting the Discharge charge setting from 10A to 15A. Whenever my aircon's compressor kicked in, the discharge current ramped up from 7A to 11A, which tripped the Inverter's Load output. Output restored, then a few minutes later it tripped again. After adjusting the Max A Discharge  in the "Battery Setting" Menu, this doesn't happen anymore.

I experiencing the F56 error ever time the grip goes off? 

I actually got this F56 error when the batteries reached the batteries shutdown percentage that was set. Mine was 20%. UPS started to beep and shutdown 1 minute later. Luckily 4 hour loadshedding session ended and battery started to charge again.

F56   with  Led Acid Bat.

Sudden Drop for no reason  98% to 34%    / or /   when grid stops and high load goes to inverter night times.

 it charges back 34% to 100% in 4 minutes.  

also Beeps sometimes 0% battery,  I wud have to go to battery setting, change battery size by 1 digit up/down then save, it works   

Not 100% correct

 

F56 can pop up if your charging current is to high. 

Try to set it to the half, like 70A.

If it work clump up every hours by 10A

I had to reduce my current from 150A to 135A.   Now it works perfect

 

Other problem could be the bms. 

I recommend always a daly bms. Bigger is better.  This way you make sure that you don't reach the phisical limits.

 

My battery is working perfectly and inverter shows on and off ac led. Once no PV and batttery the inverter shuts down. When battery is present no problem. Offgrid mode works and normal. F56 only appears when battery already drained. Instead of switching to grid mode, it shuts down since no ac input as per LCD but AC input is connected

On 2021/11/20 at 4:54 PM, Bobs said:

Hello everyone 

I have a 5kw Deye inverter with 1 US3000 pylon tech battery. Why does my inverter show error F56 and my power shuts down for 1 min the goes on like normal. The battery show 98%. Can anyone the assist.

thanks

you must change battery setting at battery volt and battery low set at 41 volt

 

I have the same issue. It wasn't an issue before, but now it chooses to rear it's head. Early mornings when I use a little bit of heating power (like switching on the kettle or dishwasher), the inverter gives the F56 fault and shuts down before restarting.

My installation is a Deye 8kW inverter, with 4 x Dyness 5.12kWh BX51100 batteries installed.

The batteries have a recommended 0.5C discharge rate, with a 1C max, so to me, it should never happen. I charge them slowly (way slower than their max charge rates), so that should also not be a problem. I'm off-grid, so it's not a grid problem either.

To me, 0.5C on 4 x 5.12kWh batteries means I should be able to pull 10kW from the batteries in total, easily, but they're tripping when I get close to 3kW. It also doesn't happen all the time, only from time to time.

I have a warranty on these things (they're not even 4 months old yet), but I need to troubleshoot myself before I get the installer out.

Found this, because I've the same F56 every day after charging 4x US5000 Pylontech. Inverter Deye 10kW cuts off power and searching for answers has been started.

I cannot change battery settings to Lithium, so it stays in Use Batt V but MAYBE with the wrong parameters.

I'm off grid now for eight days and every day troubles.

Greetings, Ad from Curaçao.

On 2025/05/06 at 7:50 PM, Ad van Loon said:

Found this, because I've the same F56 every day after charging 4x US5000 Pylontech. Inverter Deye 10kW cuts off power and searching for answers has been started.

I cannot change battery settings to Lithium, so it stays in Use Batt V but MAYBE with the wrong parameters.

I'm off grid now for eight days and every day troubles.

Greetings, Ad from Curaçao.

Based on the manual and my own experience this fault F56 comes up when your battery voltage drops below the battery alarm or shutdown value. This will typically happen when switching on a high load or even when a fridge/freezer with high surge current starts.

It should never be assumes that having a lot of battery power with a well discharged battery cannot reach any of the 2 settings mentioned.

Post your battery settings as it might provide some leads to try and work out why.

In my case I had the grid off and got F56 about 3 times in the 1st month of using my Deye 5kW while trying to find the right settings. Since making sure the timer is ticked to keep my battery above a set level no further F56 errors as is reported under DEVICE INFO.

On 2025/05/08 at 10:44 PM, Scorp007 said:

Based on the manual and my own experience this fault F56 comes up when your battery voltage drops below the battery alarm or shutdown value. This will typically happen when switching on a high load or even when a fridge/freezer with high surge current starts.

It should never be assumes that having a lot of battery power with a well discharged battery cannot reach any of the 2 settings mentioned.

Post your battery settings as it might provide some leads to try and work out why.

In my case I had the grid off and got F56 about 3 times in the 1st month of using my Deye 5kW while trying to find the right settings. Since making sure the timer is ticked to keep my battery above a set level no further F56 errors as is reported under DEVICE INFO.

This makes sense, as mine trips every time I switch on a high current device, like the kettle or the air fryer. Only happens in the mornings, once sun is shining it's not a problem.

Can you perhaps share the settings you changed? I just want to contact my installer and have something to point him into the right direction. In my case it definitely looks like it's the batteries shutting down, and not the inverter. The inverter still reads "on", with the house just drawing 0W, so it looks like the batteries are shutting down.

My problem is getting worse, though. At the start I could run the coffee machine and the kettle comfortably when I wake up. Now I need to carefully choose what I can switch on, and it's annoying as hell.

EDIT: Sometimes it even switches off without the F56 error showing up on the inverter. It trips exactly like usual, and then switches on again exactly as usual, but there's no error on the error logger when I check.

Edited May 22, 20251 yr by Toxxyc

30 minutes ago, Toxxyc said:

This makes sense, as mine trips every time I switch on a high current device, like the kettle or the air fryer. Only happens in the mornings, once sun is shining it's not a problem.

Can you perhaps share the settings you changed? I just want to contact my installer and have something to point him into the right direction. In my case it definitely looks like it's the batteries shutting down, and not the inverter. The inverter still reads "on", with the house just drawing 0W, so it looks like the batteries are shutting down.

My problem is getting worse, though. At the start I could run the coffee machine and the kettle comfortably when I wake up. Now I need to carefully choose what I can switch on, and it's annoying as hell.

EDIT: Sometimes it even switches off without the F56 error showing up on the inverter. It trips exactly like usual, and then switches on again exactly as usual, but there's no error on the error logger when I check.

Get the installer to check if the batteries are charging to a high SOC or reduce your load during the night. Also set the timer to use grid say 04h to 07h or the after the time you make coffee.(use a higher SOC than what you have now) This will cause grid to assist to keep the battery at a high enough voltage to prevent error f56.

Also investigate if at a highish SOC why the battery voltage dips too low.

Edited May 22, 20251 yr by Scorp007

I don't have grid. I'm completely off-grid.

On a related note, I noticed today the batteries aren't charging at the same SOC. It looks like some of the batteries are charging between 60 and 80% (the 4th light is flashing out of 5), and some of the batteries are charging between 40 and 60% (the third light is flashing out of 5). So I am guessing some batteries never reach their proper SOC, which could be why the low voltage is an issue in the mornings, no?

2 hours ago, Toxxyc said:

I don't have grid. I'm completely off-grid.

On a related note, I noticed today the batteries aren't charging at the same SOC. It looks like some of the batteries are charging between 60 and 80% (the 4th light is flashing out of 5), and some of the batteries are charging between 40 and 60% (the third light is flashing out of 5). So I am guessing some batteries never reach their proper SOC, which could be why the low voltage is an issue in the mornings, no?

I would disconnect the battery/ies that are at the high SOC and then allow PV to charge the lower ones to also reach say 4 x LEDs on. With now cloud in Gauteng we are currently having good PV yields even if the day is shorter.

Yeah I'm easily generating 40kWh+ per day in the bushveld. It's just getting everything else in the house running with the batteries charging to full that's also a challenge, but I think today I should manage. I'll get them all charged until the system reads 100%, and then start switching off and letting the lower batteries charge to full as well.

Just thinking out loud, layman's 2c, wondering if it could help to limit the charge rate of the battery bank, if you're not already doing that.

I sometimes got this F56 warning at the start of loadshedding. I would be having high usage supported by pass-through of grid current, but then once the grid collapses, the rated capacity of the inverter & battery would be unable to carry the load. Shutdown, error, re-start, etc.

What I'm wondering is, if you're off-grid and doing bulk charging with all available PV, whether there's an "inertia" that prevents the supply to be met quickly enough. Let's say on the 10kW Deye with 4x5kWh Pylontech batteries, would it be enough to charge at say 120A instead of 200A, leaving the MPPT free to supply the additional load, and/or the battery charger to reverse the direction of current quickly enough? Using a 0.3C instead of 0.5C charge rate should still allow batteries to be charged in the day, while leaving headroom for daily loads.

I'm assuming here it's not an issue with the dip switches on the slave batteries being set incorrectly, such that only 1 battery is being actually "seen" by the inverter. If the BMS is connected, the Li-BMS screen could tell you that, but if someone's running in Voltage mode? Might have to go back to the manual to verify settings in that case.

Quoted:

If the BMS is connected, the Li-BMS screen could tell you that, but if someone's running in Voltage mode? Might have to go back to the manual to verify settings in that case.

My reply:

I am running close to off grid. MTD only used 10kWh grid and that is when more than 2-3 gadgets are used in the kitchen.

Still wondering why @Toxxyc is having this problem. I don't even get F56 when the lawn mower of 1.8kW starts before PV kicks in before 08h00 running from battery only with grid off. My battery is then at around 35% SOC. I use a 5kW Deye with 8kWh battery power.

The above is the reason why I suspect a battery/settings problem.

Edited May 27, 20251 yr by Scorp007

I've spoken to the installer, and his managing guy says there might be a faulty BMS. It's very weird. For example, yesterday during the day, when batteries are charging, two will flash 60% to 80% SOC (the 4th LED flashing green), while the other two will flash 40% to 60% SOC (the 3rd LED flashing green), with the inverter reporting 71% SOC. So I prioritized battery SOC yesterday (usually balance it with running devices in the house like geyser and ACs and dishwasher and so on), so that I could get maximum charge earliest in the day. Around 14:30 I hit 100% SOC as reported on the inverter (while using power for the other stuff as needed), so I started switching off batteries in the line. However, they all reported 99%~100% SOC.

So I figured "finally they're all full together" and continued as normal. During the night we ran the AC in the bedroom for 30 minutes at a time just to raise the room temp a bit, as we usually do, and we woke up to again 54% SOC on the batteries (as reported on inverter). So at 06:00 I switched on the AC again. I ran the AC until just before 07:00, when I switched it off. At that time, the battery SOC was reported at 42%.

The second I switched the AC off, the SOC tanked to 20%. It wasn't gradual, it was instant, as can be seen on the graph as well (graph's time is an hour early, ignore that):

So it looks like at least one of the batteries have got a faulty BMS. The problem is getting worse, so it also makes sense. It could be that at 42%, two of the batteries switched off, resulting in the remaining SOC halving to 20%. That's my best guess at this stage.

I'm in talks with my installer to see how we can get this sorted. I have a genny, but can't run it 24/7, so this needs to be sorted ASAP.

So after a lot of tweaking and testing, the problem can't be identified. The installer was here, they tested all the batteries, removing them one by one from the system, and the problem remains. As a solution, the system was set to lead acid on the batteries, the parameters set properly, and now the problem seems to be gone.

It's REALLY weird.

4 minutes ago, Toxxyc said:

So after a lot of tweaking and testing, the problem can't be identified. The installer was here, they tested all the batteries, removing them one by one from the system, and the problem remains. As a solution, the system was set to lead acid on the batteries, the parameters set properly, and now the problem seems to be gone.

It's REALLY weird.

I think you have got to the real problem. It seems a BMS is reporting the wrong SOC and the inverter is just acting on the data it receives. I does seem like the batteries themselves seem to be fine if they carry the load when in Voltage mode away from the comms from the Lithiums.

My Deye with a real mixture of lithium banks are working fine in Voltage mode.

20 hours ago, Scorp007 said:

I think you have got to the real problem. It seems a BMS is reporting the wrong SOC and the inverter is just acting on the data it receives. I does seem like the batteries themselves seem to be fine if they carry the load when in Voltage mode away from the comms from the Lithiums.

My Deye with a real mixture of lithium banks are working fine in Voltage mode.

Yeah overall it doesn't really change anything, except now it feels to me like something is wrong in the system. I have this constant worry that something is amiss, even when everything now works perfectly fine. Voltage mode works. System was optimised as bit more as well, and now the batteries also charge a lot faster. Dunno why, but they set the batteries to only charge at something like 680W max per battery, so it took the whole day to charge. Turns out they can charge a lot faster than that, and can now go from almost dead to full in like 4 hours, which is epic and opens up my mornings a lot more.