jbroo

This is good to know, thanks. It does. The range for bulk charging is 25-30v. I've set bulk to 28.0v now. How does one set absorb voltage/time on these inverters? So looking at the inverter vs the balancer (I'm inclined to believe the balancer since it works on finer tolerances): Inverter: 26.99 Balancer: 13.46 + 13.42 = 26.88 So that's about 0.1v discrepancy. Based on the above, I should then set the inverter to 28.1 bulk, 27.1 float to compensate for the incorrect reading? At the moment I charge only from utility. I don't know where to set absorb voltage/time. What would you recommend for equalisation, should I need to set this when I add PV? These are the available settings: What are the "back to charge/discharge" settings exactly? They don't seem to do much regardless of value...

I don't think they can ever reach this? The difference here being bulk charge voltage vs voltage of the battery, and at 100% SOC at rest, the battery would be at 13.8-14v (and 13.6v under load). You could in theory bulk charge at 14.6v but the battery would never reach 14.6v itself...

How do you get a week between charge cycles? My inverter will start charging immediately after any grid interruption. I would rather reduce the cycles and drain them to 20% SOC before charging again if possible.

Hi all, Firstly, apologies, I'm sure this question has been asked many a time on this forum and others. I'm hoping the gurus here may have a more definitive answer for me. What are the best recommended bulk and float charge voltages for an Axpert inverter (Synapse 3.0V+) running a 24V battery pack (a pair of 12V 200Ah batteries connected in series)? I don't have any PV connected (yet). My battery specs: I have an HA11 battery balancer installed across the batteries so can monitor individual battery voltage. One battery is always about 0.05v lower than the other. I have tried: Bulk: 28.8, Float 27.4 Batteries settle at around 13.65v. Inverter always charging them. Bulk: 28.4, Float: 27.2 Batteries settle at around 13.55v each. Inverter is always charging them. Bulk: 28.4, Float: 27.0 Batteries settle around 13.45v each. Inverter is always charging them. This is my current preferred setting. Bulk: 28.8, Float, 25.0 This float is as low as the Axpert allows. Batteries charge up to 13.75v, then inverter stops charging altogether (probably BMS cutoff). They then gradually drop off, and at around 13.30v or so, the inverter seems to bulk charge again and they go up to 13.75v. This cycle repeats roughly every 10 min, but is the only time I can get the inverter to actually stop charging the batteries for some period of time. I've also consulted various sources on the internet, with the best two I have found below: https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/ https://www.canbat.com/how-to-charge-lifepo4-batteries/ All sources suggest that float should be disabled for LiFePo4 if possible (not possible on Axperts), otherwise set to around 13.6v (per battery). From what I have read, the optimal values (assuming the inverter's readings are correct) are around 28.4v (14.2v per battery) for bulk, and 27.0v (13.5v per battery) for float, as a good life-prolonging setting. Am I wrong? I've been using this but just not sure if the batteries are getting properly charged. I have not found any settings for Absorb on the inverter (unless it's differently named). What is best here? My aim is to get a good balance of longevity of the batteries vs performance but also don't want to trash them with bad charge settings. Currently I have no trouble getting through a 2 hour load-shedding period with an average draw of 500W. I have not tested how much backup time I get until batteries fully discharge. Any advice is appreciated.

So, as others on this forum and online have attested, some Axpert models tend to have noisy fans, with no speed control. They are either on or off, and when on, they are fairly loud. In my case, I don't have a garage or distant room for my installation, so my inverter is installed in close proximity to my bedroom, and the fan noise is somewhat annoying. I've been studying the fan pattern and it is regular as clockwork - the fans come on at 41°C and stay on until the inverter heatsink temperature drops to 31°C. The fans then turn off, and the temperature slowly increases, until the fans come on again at 41°C. This pattern repeats every 10-15 minutes, ad nauseum, and is something of a design flaw in my opinion. It's a mystery why there is no variable speed on these... As a proof of concept I rigged a 12V PC case fan to the side of my Synapse, over the top vent, sucking hot air out. I left this on for about 45 minutes. The results speak for themselves. The temperature on the unit dropped to 29-30°C and remained there. The inverter's own fans never came on during this period, and the PC case fan is virtually silent. It's possible that under heavy load/charging, the temperature might rise enough to trigger the built-in fans, but that would be an exception, not the norm. I may open up the inverter case and see if I can fit the fan inside permanently (there appears to be space) or get a smaller fan. I think this would ultimately prolong the life of the inverter (running cooler) and the fans (less usage), as well as add to quality of life (less noise). Has anyone else done something similar? Is there a 12v output on the PCB I could use to power the fan? Currently the plan is to use a 12v adapter connected to a nearby plug. I will post an update here when I've made a more permanent modification.

@RoannG have you still got this inverter? I have a very similar setup, Synapse 3.0V+ with 2 x 200Ah LiFePo4 batteries in series, an HA11 balancer, and the same firmware versions. I don't have PV yet. Have you had any issues with charging or the "early float" bug? My charge settings are 28.4v for bulk, 27.0 for float - conservative as I would like to cycle the batteries but stay within 10-90% SOC to prolong their life. Any tips are appreciated.

It looks like the Synapses are in fact genuine Voltronics. I've checked the various tell-tale signs that @Coulomb has posted elsewhere (serial number on device reply, printing of 'Phi' symbol on label, etc). I also have the attached document from the local agents (Rubicon). SZNTC2111005SV00_SYNAPSE3.0_SYNAPSE3.0V_EN_62040-1_Cert.pdf I have a Synapse 3.0V+, and so far, so good. @Coulomb is there still no new firmware for these? Mine is: VERFW:00009.56 VERFW2:00003.39

Thanks. It's free, but has not been updated for a few years. Reached out to the developer but got no reply. If Play Store says it's not available for your device, find it on APKPure and install the APK directly.

Hi everyone, I've made my own mobile monitoring solution using the following software/apps, and my own code, running on my Raspberry Pi 1B. The inverter is connected to the Pi via USB. This software runs on the Pi for polling: https://github.com/manio/skymax-demo I use this app on my phone for monitoring: https://play.google.com/store/apps/details?id=com.cpk.iotdashboard&hl=en_US Credits to the original developers of the above software. My own custom script does the polling every 10 sec and dumps the data to JSON files in the Pi's public webserver folder. The mobile app queries the JSON files every 5 sec. Mobile app results (extensive config required in app): I have also built a PHP based web monitor that can be viewed from any browser and refreshes automatically every 10 sec. PHP web monitor (minimal config required): Since I run Zerotier One on my Pi and phone, I can monitor my inverter from anywhere, 24/7. If someone is interested, I'm happy to share my code and some basic instructions on how to set this up. It does require some tinkering so it's not for the novice user.