SolarFrans Posted February 12, 2019 Share Posted February 12, 2019 Hi guys, Sorry if this is a bit vague, but I've been noticing this behaviour several days in a row now and I'm hoping someone has a suggestion. In the morning, my battery is about 25% charged, and, with normal sunny weather, it reaches full charge somewhere in the afternoon (I've set the Axpert to Only Solar, so this only happens with sufficient sunlight - but that hasn't been a problem so far). At this point I still have about 900W of load that can be handled by PV, battery, or a combination of both. Now I've noticed that for a while, the Axpert will switch off PV, drain the battery a bit, then turn on PV again to charge the battery back. All good. But at some point the Axpert stops pulling power from the PV alltogether and only handles the load from the battery. So now the battery is being drained (it's down to 90% now) even though there's enough power on the PV to handle the load and/or (re)charge the battery. I've reset the Axpert once in this state and then it happily starts charging the battery from PV again. But I'd think it shouldn't end up in this state to begin with? Thanks for any help you guys can give me! Frans Quote Link to comment Share on other sites More sharing options...
Coulomb Posted February 13, 2019 Share Posted February 13, 2019 10 hours ago, SolarFrans said: In the morning, my battery is about 25% charged, You didn't say what sort of battery you have; hopefully it's not lead acid, if discharging to 25% SOC. Quote But at some point the Axpert stops pulling power from the PV alltogether and only handles the load from the battery. So now the battery is being drained (it's down to 90% now) even though there's enough power on the PV to handle the load and/or (re)charge the battery. Presumably, you're running factory firmware. The voltage thresholds are not very good for lithium batteries, they are really set up for lead acid. In particular, when in float mode (battery has charged), the voltage has to come down a long way (4.0 V with factory firmware) before it will start a new bulk charge. This voltage difference is reduced to 1.2 V when with the LFP version of the patched firmware. Four volts less than the float setting is nearly dead flat on a LFP battery. However, even in float mode, the SCC should be charging from solar any time that the battery is less than the float voltage setting. That's how it "covers" loads in the afternoon. Is your charging LED on (bulk/absorb), flashing (float), or off (not charging) in this situation? Finally, is it possible that you have a clone? Some clones seem to have odd problems with solar charging. See the section just above the first photo in this post to help identify a clone. Quote Link to comment Share on other sites More sharing options...
SolarFrans Posted February 17, 2019 Author Share Posted February 17, 2019 On 2019/02/13 at 2:04 AM, Coulomb said: You didn't say what sort of battery you have; hopefully it's not lead acid, if discharging to 25% SOC. Li-ion (Pylontech US3000B). From what I read you can take them down to 10% SoC, but they'll live a lot longer by staying above 20%, so I'm sticking with that. Quote Presumably, you're running factory firmware. The voltage thresholds are not very good for lithium batteries, they are really set up for lead acid. In particular, when in float mode (battery has charged), the voltage has to come down a long way (4.0 V with factory firmware) before it will start a new bulk charge. This voltage difference is reduced to 1.2 V when with the LFP version of the patched firmware. Four volts less than the float setting is nearly dead flat on a LFP battery. Float was set to 54V; I lowered it to 53.2V today, to see if that might change something (it didn't really). Generally the battery hovers just over 49V when it's powering load, but without load it won't go under 50V, so I guess it's not crossing that 4V barrier then. Firmware is factory (I cannot upgrade, see below). Quote However, even in float mode, the SCC should be charging from solar any time that the battery is less than the float voltage setting. That's how it "covers" loads in the afternoon. Is your charging LED on (bulk/absorb), flashing (float), or off (not charging) in this situation? The charging LED on the Pylontechs? I'll have to check. I only noticed the 6 SoC LEDs and a "run" LED. The "run" one just comes on every once in a while and goes off again. I guess you could call that flashing It just seems a bit slow to be considered that. I'll take another look next time things end up in this state to check and let you know. The display on the Axpert just shows the battery powering the load, and no power (utility or PV) coming in at all. Quote Finally, is it possible that you have a clone? Some clones seem to have odd problems with solar charging. See the section just above the first photo in this post to help identify a clone. It looks like a custom-labeled one, but not a clone. However, firmware 74.10 so not upgradeable Quote Link to comment Share on other sites More sharing options...
Coulomb Posted February 17, 2019 Share Posted February 17, 2019 4 hours ago, SolarFrans said: Float was set to 54V; I lowered it to 53.2V today, to see if that might change something (it didn't really). Generally the battery hovers just over 49V when it's powering load, but without load it won't go under 50V, so I guess it's not crossing that 4V barrier then. Firmware is factory (I cannot upgrade, see below). Ok, so it won't start bulk charging again. But as long as it stays in float mode, it should still charge the battery, just not to as high a voltage. 4 hours ago, SolarFrans said: The charging LED on the Pylontechs? Sorry, I wasn't clear. I meant on the Axpert. Quote The display on the Axpert just shows the battery powering the load, and no power (utility or PV) coming in at all. Ok, I meant the middle LED on the Axpert, labelled "CHG". But the lack of the PV icon is a problem (I assume we're talking about daytime, after a full charge, say mid afternoon). Quote It looks like a custom-labeled one, but not a clone. However, firmware 74.10 so not upgradeable I've put a lot more "clone detection logic" into an AEVA post: Do I Own a Clone? Some clones seem to have a lot of trouble with PV charging, so perhaps make one last check that it's not a clone. On 2019/02/12 at 11:04 PM, SolarFrans said: I've reset the Axpert once in this state and then it happily starts charging the battery from PV again. Does it bring back the PV icon and start using PV power if you just remove the PV input for a few seconds? Leave the Axpert running for this test. This would in effect reset the Solar Charge Controller without resetting the main DSP. It takes the SCC a minute or so to fully get going so be patient. If that succeeds, it means that the problem is with the SCC, or perhaps your PV voltage is marginal (either too high or too low). What PV voltage do you see when it won't charge? I suppose it might be zero if the PV icon is off, so you might have to use a multimeter. Quote Link to comment Share on other sites More sharing options...
SolarFrans Posted March 23, 2019 Author Share Posted March 23, 2019 So it seems one of the fuses between the Axpert and the Pylontechs was wonky and stopped it from charging, sometimes. At some point that fuse died completely and the whole thing shut down (no battery power = no inverter). Now with new fuses, everything seems fine. So if anyone ever experiences this behavior, check your fuses. Quote Link to comment Share on other sites More sharing options...
ojeysky Posted February 6, 2020 Share Posted February 6, 2020 On 2019/02/13 at 1:04 AM, Coulomb said: Presumably, you're running factory firmware. The voltage thresholds are not very good for lithium batteries, they are really set up for lead acid. In particular, when in float mode (battery has charged), the voltage has to come down a long way (4.0 V with factory firmware) before it will start a new bulk charge. This voltage difference is reduced to 1.2 V when with the LFP version of the patched firmware. Four volts less than the float setting is nearly dead flat on a LFP battery. Finally, is it possible that you have a clone? Some clones seem to have odd problems with solar charging. See the section just above the first photo in this post to help identify a clone. I think my challenge is similar to this and it seem my LFP battery is not getting well charged. How do i work around this? my current settings is now 27.8/27.6 (bulk/float) Quote Link to comment Share on other sites More sharing options...
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