zak687 Posted July 28 Share Posted July 28 We have a Kodak OG 5.48 inverter with a Greenrich 3.68kwh battery in a cabin, completely off-grid, just running refridgerator, wifi and self-consumption (which is surprisingly high for this inverter). After a run of cloudy days the battery was dying at a preset (battery setting) of 45v. When sun returned the system would not wake up unless the battery was power-cycled, but given cabin is unattended in the week, this was not possible. Set up with USER settings rather than pylontech (that is another story but not for now). Using Watchpower, we then tried setting the inverter to switch off at a voltage higher than the battery minimum (we set it at 47v while the battery cut-off remained at 45v) hoping the inverter would switch off but the battery stay on, so that when sun returned the inverter could resume charging the battery which would still be awake. We set the "back to discharge" voltage to 52v hoping that when the battery was being charged again, the inverter would start supplying the AC output once more when the battery reached this voltage. WIth this last run of cloudy days it worked to cut the AC output at 47v with the battery still alive, but when the sun returned the output has not started again. I am not at the inverter to see what is happening, but when I tried to emulate while on site (by disconnecting and reconnecting the solar input), I also observed that the AC output did not start again when the voltage reached the back-to-discharge voltage, unless I power-cycled the inverter. I hoped it was an anomaly in my emulation, but seems not. 1. What is the correct configuration for an off-grid implementation with this inverter which would enable it to auto-recover when sun returns? 2. Are we interpreting the back-to-discharge voltage correctly? 3. Setting the cut-out voltage higher so that the inverter cuts the output while the battery sill has some charge, can result in Fault 04 frequently occuring, as this threshold and the operative voltage are often within 4v of each other. We had wanted to set it higher than 47v, but for this fault. Thanks for the advice. Quote Link to comment Share on other sites More sharing options...
chrisc Posted July 28 Share Posted July 28 Is charge priority set to Solar First? Quote Link to comment Share on other sites More sharing options...
zak687 Posted July 28 Author Share Posted July 28 (edited) Yes, SBU is selected (program 1) Or did you mean Program 16 - cannot reall what that is set as, but all the options in the manual suggest solar would be used? Edited July 28 by zak687 Quote Link to comment Share on other sites More sharing options...
TaliaB Posted July 29 Share Posted July 29 (edited) 10 hours ago, zak687 said: Yes, SBU is selected (program 1) Or did you mean Program 16 - cannot reall what that is set as, but all the options in the manual suggest solar would be used? Program 1 set to SBU as mentioned program 16 set to OSO(solar only) as this is your only charging source (no utility). Your problem without utility is your battery capacity in an off grid setup running continuous load. Setting voltage point back to battery mode(13) set it to 54v or higher to ensure the battery gets charged while solar is available( not sure if(13) it is relevant for utility charging only) as you will eventually deplete the battery in poor solar conditions. My suggestions: 1. Up your battery capacity for at least 4 days redundancy. 2. Get remote monitoring so you can at least see what your system is up to, Solar Assistant comes to mind. Edited July 29 by TaliaB Antonio de Sa, zsde and Derek3 3 Quote Link to comment Share on other sites More sharing options...
zak687 Posted July 29 Author Share Posted July 29 Thanks Talia. Have some remote monitoring (this project), just not all sensors, but it is powered by the inverter and goes down when the inverter goes down. Have considred trying to manage it remotely with more effort to keep the gizmos up when the inverter is down, but would be much easier if the inverter simply came back to life when there was sun, which I was led to believe was possible. Looking for a second battery.....if anyone is flogging a Greenrich P3686, let me know! Quote Link to comment Share on other sites More sharing options...
Beat Posted July 29 Share Posted July 29 15 hours ago, zak687 said: Are we interpreting the back-to-discharge voltage correctly? Since your system has no grid connection settings 12 and 13 have no meaning. These determine when the system should switch to grid and recharge the batteries from grid when battery voltage is low and switch back to battery (back-to-discharge) mode at the set higher voltage. If there is no grid present the system will not switch. Make sure all possible automatic restarts are enabled. Low battery cut off (29) at 45V seams reasonable but check with the battery specs. Setting 16 "charging source priority" should be set to OSO (solar only). But if you want to recharge from a geni you need to set it to CSO. Scorp007 1 Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 29 Share Posted July 29 7 hours ago, Beat said: Since your system has no grid connection settings 12 and 13 have no meaning. These determine when the system should switch to grid and recharge the batteries from grid when battery voltage is low and switch back to battery (back-to-discharge) mode at the set higher voltage. If there is no grid present the system will not switch. Make sure all possible automatic restarts are enabled. Low battery cut off (29) at 45V seams reasonable but check with the battery specs. Setting 16 "charging source priority" should be set to OSO (solar only). But if you want to recharge from a geni you need to set it to CSO. I wonder if setting 12 and 13 are not still used even with no grid. They can perhaps be of use when the battery should be used during load higher than what PV can produce. Another point is setting 16. CSO is only of value if a genny is used. If not any of the charging modes will work as there is no grid to charge even if grid and solar are selected to charge at the same time. Even when utility charging is selected but not present then PV will still be used when available. That's how I use this setting. Quote Link to comment Share on other sites More sharing options...
Chris Louw Posted July 29 Share Posted July 29 @Scorp007 I run the Axpert with no utility power connection . Setting 12 and 13 is used to control start/stop of a pool pump and geyser . The charging 16 was left on solar/utility. When the load is more than the PV the balance is taken from the batteries . This does not have any effect on the battery charging. Batteries is charged as set on 26 and 27 . Scorp007 1 Quote Link to comment Share on other sites More sharing options...
zak687 Posted July 29 Author Share Posted July 29 (edited) These are the settings I am changing - the screenshot is for a 24v system, but am setting a) to 47v and b) to 52v. Have bulk, float and equalisation all set at 56v. The watchpower manual says "Back to discharge voltage: When battery voltage is higher than this setting voltage, battery will be allowed to discharge." Not sure which setting b) aligns to but probably 13? Does anyone with an off-grid setup have their system resuming unattended when sun returns? Edited July 29 by zak687 Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 30 Share Posted July 30 Wild idea: Make sure that there is a 2-wire cable connecting from the Solar Charge Controller to the main board, not corroded, has continuity etc: At least, I think that's the right connector to wake the inverter when the sun comes back. It might be that the battery's BMS has disconnected the inverter because the battery voltage is so low. If so, you may have to raise the low DC cutoff voltage setting, so the battery's BMS is happy to let the battery continue connecting to the inverter. Scorp007 1 Quote Link to comment Share on other sites More sharing options...
zak687 Posted July 30 Author Share Posted July 30 (edited) Thanks Coulomb. Would one assume this cable is present and functional when supplied as new? In my emulation when I reconnected the solar the battery started charging and the LCD on the inverter came on showing the battery was charging, it just did not restart the output (AC). Edited July 30 by zak687 Quote Link to comment Share on other sites More sharing options...
Coulomb Posted August 1 Share Posted August 1 On 2024/07/31 at 5:37 AM, zak687 said: Would one assume this cable is present and functional when supplied as new? One would hope so. But it's something you can do without for months, until you need it after many rainy days, so it might have been overlooked. It could also not be crimped properly, critters ate the cable, etc etc. But it's a long shot. Basically, when the sun comes up, it effectively does the same thing that pressing the start button after the inverter has been off, i.e. starts the main power supply. On 2024/07/31 at 5:37 AM, zak687 said: it just did not restart the output (AC). When it wakes after a long wet period, it should determine that it's in fault mode with fault code 04 (battery voltage low). If the battery eventually passes certain thresholds, it should move from fault mode to battery mode and actually power the loads. That's assuming that the load switch is on all this time. If turning off and on the solar power during the day starts the inverter but morning sun does not, that suggests that there is something weak in that "wake up" circuit. Opto couplers are known to fade with age, and capacitors are known to dry out. Quote Link to comment Share on other sites More sharing options...
zak687 Posted August 1 Author Share Posted August 1 So I think the wake up is working as the LCD panel comes on with solar and shows that it is charging the battery but not the supplying the load. But fault mode might be the issue with respect to the load, if it requires that fault code 4 clears in addition to getting over the threshold to restart the output. That requires the voltage to be 4v higher than the low voltage cut-out for the inverter. And that is difficult to emulate without actually running the battery down. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted August 1 Share Posted August 1 1 minute ago, zak687 said: So I think the wake up is working as the LCD panel comes on with solar and shows that it is charging the battery but not the supplying the load. But fault mode might be the issue with respect to the load, if it requires that fault code 4 clears in addition to getting over the threshold to restart the output. That requires the voltage to be 4v higher than the low voltage cut-out for the inverter. And that is difficult to emulate without actually running the battery down. As I don't know the HV models the error 4 must normally be reset via switching off and on again after the system is healthy. I see this as a good feature that you must acknowledge the serious condition 1st. One way of getting it reset remotely would be to have a smart switch via APP to perform this function. This means using the battery even if it is low to say controller a 12-24V Sonoff as long as WiFi remains on. Quote Link to comment Share on other sites More sharing options...
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