Ben Harper Posted September 25 Share Posted September 25 I've now fried two RS232-to-USB adaptors, which I'm using between a Raspberry Pi 5 and a Kodak/Voltronic/Axpert 6.2KW inverter (OGPLUS-6.2). There's obviously something fishy with my setup, and this is where it gets really strange: IF Raspberry Pi is powered and connected to inverter (via RS232) AND grid power is disconnected (2 pole breaker into inverter is off) THEN inverter can no longer talk to battery (error 61) The Inverter->Battery comms only fail under those exact conditions, which tells me there's something fishy going on with grounding or something. Here are the details of my setup: Inverter: Kodak OGPLUS-6.2. This is one that blends power from grid (I can tell because grid voltage == output voltage, even in SBU mode). Batteries: 2x Pylontech UP5000, connected via Kodak-supplied BMS cable Raspberry Pi 5, powered from output side of inverter, via factory supplied Rpi5 power brick (which is a 2 pin plug, no earth) RS232-to-USB adaptor connected to inverter via Kodak supplied RJ45 to RS232 cable, and to Rpi5 via USB Neutral is bonded to earth at the grid input to my house I've ordered a USB isolator, and I hope this will solve the problem. But I'm so curious to figure out the root cause here. I would think the Rpi5 would end up with a reference ground equal to the ground line of the RS232 adaptor/USB. But I don't really know what I'm talking about regarding electronics and grounding, etc. Quote Link to comment Share on other sites More sharing options...
Marius2001 Posted September 25 Share Posted September 25 I'm not an Expert but also have a Kodak and Pylontech setup and have learned the following 1. Issue might be neutral bonding - You've mentioned that you have neutral bonded to earth at the grid input to your house, but if the double-pole breaker is OFF is the NE bond still in place? 2. Raspberry v4 had some issue where if power is supplied via Type-C except the "primary port" or something that it might affect either USB ports. You can try running Type-C from any non-related power source just to double-check the power supply. Quote Link to comment Share on other sites More sharing options...
Ben Harper Posted September 25 Author Share Posted September 25 (edited) If the double-breaker is off, then the NE bond is no longer in place. HOWEVER, the same error code 61 happens even if I just flip the positive grid line off (i.e. the single pole Red line into my house). I should try this, but I need to wait for a new RS232-to-USB adaptor. Edited September 25 by Ben Harper Quote Link to comment Share on other sites More sharing options...
Marius2001 Posted September 25 Share Posted September 25 Just out of curiosity - why don't you let the Raspberry PI manage the comms between Inverter & batteries? Reason asking - I've have 2x Kodak with some pylontechs and find that my Raspberry PI (with ICM software) works quite well including resolving the (high) charging voltage 52.4 vs 53.2v problem. I'm 99% off grid and although my new Kodaks (2x OG5Plus) (recently replaced my Axpert due to failure) do support direct 485 comms to batteries my config without this cable works actually quite well. Quote Link to comment Share on other sites More sharing options...
Ben Harper Posted September 25 Author Share Posted September 25 I didn't even know that was possible. What software are you referring to on the Pi? Quote Link to comment Share on other sites More sharing options...
Marius2001 Posted September 25 Share Posted September 25 I'm using ICM - there are many options but this one works best for me - also added Tasmota devices to manage geysers, pool etc. https://iccsoftware.co.za/ Quote Link to comment Share on other sites More sharing options...
Kalahari Meerkat Posted September 26 Share Posted September 26 23 hours ago, Ben Harper said: IF Raspberry Pi is powered and connected to inverter (via RS232) Is the inverter RS232 or TTL level serial? If it is RS232, what RS232 to presumably USB adapter are you using? Basically RS232 has Voltage levels from -15V to +15V, possibly, even if it is only 5V, the it should still go from -5V to +5V, which most TTL Serial to USB adapters would likely not be happy with... Quote Link to comment Share on other sites More sharing options...
Beat Posted September 26 Share Posted September 26 I did have a similar problem: When I connected the BMS with RS232 and simultaneously the Axpert inverter via USB to the same laptop I burned the inverters communication board. I measure around 40V difference between BMS comm ground and inverter comm ground. Luckily there was no other damage. I now use separate laptops to monitor BMS and inverters. The other solution would be to use an optocoppler. Quote Link to comment Share on other sites More sharing options...
Ben Harper Posted September 26 Author Share Posted September 26 3 hours ago, Beat said: I did have a similar problem: When I connected the BMS with RS232 and simultaneously the Axpert inverter via USB to the same laptop I burned the inverters communication board. I measure around 40V difference between BMS comm ground and inverter comm ground. Luckily there was no other damage. I now use separate laptops to monitor BMS and inverters. The other solution would be to use an optocoppler. Ouch! You'd think they'd warn us! Quote Link to comment Share on other sites More sharing options...
Ben Harper Posted September 26 Author Share Posted September 26 5 hours ago, Kalahari Meerkat said: Is the inverter RS232 or TTL level serial? If it is RS232, what RS232 to presumably USB adapter are you using? Basically RS232 has Voltage levels from -15V to +15V, possibly, even if it is only 5V, the it should still go from -5V to +5V, which most TTL Serial to USB adapters would likely not be happy with... I don't know! It's a Mecer brand, that's all I know. Quote Link to comment Share on other sites More sharing options...
Ben Harper Posted September 26 Author Share Posted September 26 I've ordered a USB isolator, and will be using that going forward. Quote Link to comment Share on other sites More sharing options...
Coulomb Posted yesterday at 09:45 Share Posted yesterday at 09:45 Presumably the isolation in the cimm port has broken down somehow. It's by far not the only time I've heard of this. My guess would be the small transformer on the comms board. In this model, it would be in the removable display. An isolator should fix the problem. Quote Link to comment Share on other sites More sharing options...
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