Technical Support

Thanks for your help previously. I decided to buy a Sunsynk, and have now fitted it. If you read my previous topic, I then had only a single pair of cables coming from my two solar panel strings to my inverter, with a combiner at the panels and and a splitter at the inverter end, as I had been told that that would be OK by the previous inverter supplier. However I was convinced by others since that this would cause problems for the MPPT trackers, and might have been the reason why my previous inverter wouldn't work properly. So I have replaced that single cable pair with two cable pairs, and the system is now completely separate up to the inverter solar imputs. The solar side now seems to be working fine.

My remaining problem is with the batteries. I have 3 off US5000 Pylontech batteries, wired in parallel using Pylontech cables and an isolator / fuse box, all supplied by the UK company who sold me my initial system. I have connected them to my Sunsynk inverter, and in some ways they seem to be communicating with the inverter. The batteries all show they are 100% charged, and the inverter says that also. The inverter knew figures like charging voltage, float voltage etc without me inputting these. However it didn't know their capacity, it had what I guess is a default figure of 100 Ahr. Having 3 in parallel, the correct figure is 300 Ahr, which I input to the inverter.

However, the batteries are not working correctly. When I put a load on, eg the oven, I can see that the house is importing say 2.5kW and if solar is then switched on, I can see that the inverter is feeding solar power into the house and so contributing to the load and reducing the import from the grid. That's fine. However the batteries are feeding next to nothing, about 70 watts. If I switch off the PV isolator, the AC import goes up due to the loss of solar electricity, but the battery remains feeding only about 70 watts.

If I tap into the setup / battery setup, the type is Lithium, protocol is CAN, the little box below that is 0 (zero), the BMS_ERR_STOP box is unticked, and I've set the capacity to 300Ahr and the max charge and discharge rates to 80A.

If I tap on the setup / LI BMS icon, I get a screen mainly of numbers, with an upper part showing 0.00V, 0.00A, -100C, 0%, 0Ahr, etc, and a lower area with lines numbered 1 to 25 with all values on all lines being zeros as if it has copied the values in the upper part a number of times. This is quite different to the screen which I can only see unclearly on Keith's youtube videos, but the screen there looks much simpler with perhaps 2 columns of 4 lines of text and maybe numbers on each. I heard in some videos that this indicates a communications error.

My battery comms lead is going from the upper middle port "A/CAN" (where the end of the lead labelled "PYLON" is plugged in), and it goes to the inverter upper left port "BMS 485/CAN".

Please can anyone spot what's wrong? I'm sure it must be a setting, but I can't find it. Or perhaps a faulty com lead? But it worked OK with my previous inverter.

Thanks for any help 😊

Stuart