Hi Guys. I need some expert opinions on a few things. I have been trying to get this sorted for more than a year now. ACDC has been of very little help thus far and unfortunately I don't see it changing.

Our setup is as follows: 

1.    ACDC branded Inverter model PV18-5K-48VDC.
2.    ACDC branded Lithium ion battery model RS-LFP48V100AH.
3.    Six 580w Trina Solar panels.
4.    No wifi dongle or the like.

    
Note that I have contacted ACDC multiple times for assistance with the settings and it seems like they know even less than me. Unfortunately I'm now stuck with this setup and am trying to make the best of it. The system is generating more than enough power every day. My need is to also use some battery power after sunset and a little bit of utility power when the battery has dropped to a certain level.

I want the system to do the following and so far it seems impossible but maybe there's someone on here who got it right or what is the alternative?

1. When solar is available charge the battery and then power the load with the excess electricity generated.
2. When solar is unavailable, power the load from the battery down to the low voltage cutoff or 20% SOC.
3. When battery reaches the low voltage cut off or 20% SOC, supply the load from utility and charge battery from utility at the same time up to the bulk or float charging voltage, whichever applies.
4. Question: Do these Inverters have wiring to detect the battery state through the battery cables if no BMS communication cable is used or how does it work?

Below are my current settings, bearing in mind ACDC advised that no BMS cable is needed for communication. 
    01. Output Source Priority Selection: SBU
    05. Solar supply Priority: bLU
    10. Charger Source Priority: CSO
    14. Battery Type : USE
    17. Bulk Charging Voltage: 56.8v
    18. Floating Charging Voltage: 54.5
    19. Low DC Cut Off Battery Voltage: 40.5
    20. Battery Stop Discharging when Grid is Available: 46.0
    21. Battery Stop charging voltage when Grid is Available: 54.8
    37. BMS Control Message: Voltage
    38. Battery stop discharge when SOC is Available: 20%
    39. Battery stop charging when SOC is Available: 95%
 

Hi @Ziquilix,

From what I can see in your inverter's manual, they seem to have a BMS comms port. You can confirm this by checking the settings option no. 14. If "Li" is an option (it should be), then all that is needed is a comms cable between battery and inverter. That may be tricky, as it typically is a self crimped cable, depending on the pinout of the BMS port. Go read on page 10. Hopefully you can find a friend who can do that.

Other than that, you need to set no. 37 to "SOC", as voltage doesn't play a role anymore.

Setting 40 also needs to be set to "idP"

From what I have read on other Voltronic's based inverters, there could be a symbol on the screen that light's up when comms is established, or an error/fault message if not

Hope you get this going, soon.

Thanks a lot for your replay @Sidewinder. Li is an option on 14. I have setting 40 as idP yes. So the BMS cable is different from a normal network ethernet cable right? Would that be the Cat5 or something cable? 

 What currently happens with the settings outlined further down is the following:

1. When setting 19 below is reached, the system switches to power the load from utility/Eskom, but it does not charge the battery at the same time. Since the battery powers the Inverter the battery then eventually runs dry unless I change setting 01 to SUB when the time to sunrise is too far for the solar panels to kick in.

 

 19. Low DC Cut Off Battery Voltage: 40.5

Edited August 29, 20242 yr by Ziquilix

56 minutes ago, Ziquilix said:

Thanks a lot for your replay @Sidewinder. Li is an option on 14. I have setting 40 as idP yes. So the BMS cable is different from a normal network ethernet cable right? Would that be the Cat5 or something cable? 

 What currently happens with the settings outlined further down is the following:

1. When setting 19 below is reached, the system switches to power the load from utility/Eskom, but it does not charge the battery at the same time. Since the battery powers the Inverter the battery then eventually runs dry unless I change setting 01 to SUB when the time to sunrise is too far for the solar panels to kick in.

 

 19. Low DC Cut Off Battery Voltage: 40.5

One way would be to keep SUB but use a timer to cut the Eskom off at say sunset even under the USR voltage method and not via SOC. 

Then check up to what time you can run on battery at say around 48V. At that time the timer switches Eskom on and battery will stay at that level while using Eskom until it can charge via PV in the morning. This way you get to save some Eskom while running from battery. 

Without know the details of the battery the 40V cut out seems very low and I would up it to about 43V.

Edited August 29, 20242 yr by Scorp007

Hi @Scorp007, thank you. The Inverter doesn't have timer capability. I'll see to the cut off voltage.

 

@Ziquilix,

Yes, from what I can see, a std Cat5 LAN cable should work. You plug the one side into Inverter on the port marked RS485/CAN (seems to be a combo port for both protocols) and the other side in the left RS485 of the Battery ports. The other RS485 port would be used for the supplied link cable, if you ever decide to add another battery.

The manuals for your system is available on the ACDC www, in case you haven't seen them, although the battery manual doesn't show the pin layout of the RS485 port. Otherwise Google Rosen Battery Manual, as this ACDC battery is just a rebranded Rosen.

If the comms doesn't start up, you may need to make up a custom cable. for e.g. only use pin 1-3 on both sides, as pin 6 on the battery side is defined a GND, and on the inverter side (due to the dual RS-485/CAN function), it is CANH, and I wouldn't want to ground a line that is supposed to be active, even if it is not used.

@Scorp007's increased voltage for low cutoff is good.

Regarding the timer, yes that would be a external 3rd part device, something like an CBI Astute Wifi switch, except those are only rated for 30A's, you would need to get something a bit more oompf. (Normally 63A?), so you can program the timer /and or control it remotely, else you need to walk to the DB and manually throw the switch☹️. Hopefully once your system is working fully, it should not be needed.

Edited August 30, 20242 yr by Sidewinder

Thanks so much guys for the advice. When I get it working I'll be sure to come back and post what I did.

Edited August 30, 20242 yr by Ziquilix

6 hours ago, Ziquilix said:

Hi @Scorp007, thank you. The Inverter doesn't have timer capability. I'll see to the cut off voltage.

 

With timer I meant an external timer and better to have a remote unit like @Sidewinder suggested. 

A 30A unit can do as well as a 5kW draws less than 30A as long as the MCB is suitably selected. 

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