Leondk Posted June 30, 2017 Share Posted June 30, 2017 Hi, I have a potential problem Axpert 24v inverter 2 ops240 batteries (brand new) Off grid with generator backup. So today the batteries were on 25v and I started the motor to charge them, within 5 minutes the axpert says the battery voltage is 28.8 (that is my bulk and float setting voltage) and then the charging light stays on such indicates the batteries are full and not charging anymore. As soon as I put the motor of the batteries go back to 25. Something. What could be the problem here? Quote Link to comment Share on other sites More sharing options...
___ Posted June 30, 2017 Share Posted June 30, 2017 2 hours ago, Leondk said: So today the batteries were on 25v and I started the motor to charge them, within 5 minutes the axpert says the battery voltage is 28.8 (that is my bulk and float setting voltage) and then the charging light stays on such indicates the batteries are full and not charging anymore. As soon as I put the motor of the batteries go back to 25. Something. What could be the problem here? That sounds perfectly normal... A 12V battery (for example) when fully charged and simple standing there, leave it for a few hours so the charge levels can stabilise nicely, will read between 12.5V and 12.8V. That's around 25V. A full battery will quickly rise to absorption level (14.4V, or 28.8V for the 24V bank) with the application of very little current. When my 200Ah batteries are full, I can push them to absorption voltage using a piffling 1.5 amperes. Leave them alone and they quickly drop to mid-25Vs again, which once again is perfectly normal. What you will also see is that when you start to discharge, the voltage will initially drop and then pick up slightly. The harder you discharge the lower the voltage. Running at 23V doesn't necessarily mean the battery is empty, it might just mean it is working hard. That is the entire point of the SoC dance and the reason people install the Victron BMV: Because voltage doesn't tell you the full story. The only thing you can deduce from voltage is a guestimate, and only if the battery is open circuit. And even then, at 25V there is no reason to panic and start generators... that's practically full! Lithium Ion is even "worse". A Li-Ion battery sits at 25.8V for almost the whole of the cycle, only dropping off towards the end. That's one reason that they are popular: Much better voltage efficiency. Quote Link to comment Share on other sites More sharing options...
___ Posted June 30, 2017 Share Posted June 30, 2017 2 hours ago, Leondk said: charging light stays on such indicates the batteries are full and not charging anymore Also, I have to say more about this. As I said in the previous post, a 24V lead-acid battery that is at rest, receiving no charge or discharge, will sit below 26V, maybe slightly above. If the voltage is above 27V, then you can know without the shadow of a doubt that the battery is definitely charging (albeit very slowly perhaps), that is, some current is being passed through it in order to cause the voltage to rise above the resting voltage. At this point, the charger might somehow visually indicate that it has changed mode from Bulk to Absorb. I don't know how the Axpert's visual indicators work, so I cannot comment on that. The Vickys have a solid yellow LED to show bulk and absorb, switching to a flashing yellow when it goes to float. SilverNodashi 1 Quote Link to comment Share on other sites More sharing options...
Leondk Posted July 3, 2017 Author Share Posted July 3, 2017 ok thanks, i thought that if it is fully charged it will say 28.8v and then work its way back to 24v as it discharges. So if i understand you correctly at 25v it is still pretty full and therefore it should go into float very quickly?? does anybody know what software you get with a Axpert to monitor on a laptop. This might be very usefull to take the guesswork out Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted July 3, 2017 Share Posted July 3, 2017 2 hours ago, Leondk said: does anybody know what software you get with a Axpert to monitor on a laptop. Try Manie's ICC here Quote Link to comment Share on other sites More sharing options...
Leondk Posted July 4, 2017 Author Share Posted July 4, 2017 Chris, i see that you also have the Axpert Inverter, could you maybe shed some light, when i am running on battieries alone the system gives me a low voltage warning on 24,5volt but on the axpert it is set to only cut out on 24volt. so according to the previous answers here there is still plenty of power left in the batteries. Is there something i am missing or should i just set the cutout voltage to 23.5? i am not so keen on that because i don't want to ruin my very expensive investment in batteries Quote Link to comment Share on other sites More sharing options...
___ Posted July 4, 2017 Share Posted July 4, 2017 Maybe it has a pre-alarm feature? So it starts warning a little before the real thing happens? My inverter does that about 0.2V before the limit. Again, voltage is a poor measure of State of Charge. A battery working hard at 23.5V might be perfectly fine, if you take the load off it might bounce back to over 25V depending on the real state of charge. The cut-out voltage is a safety function. You should not set it too high, otherwise the inverter might cut out on the odd high load while the batteries are still fine. You can set that cut-out as low as 21V, that is technically the voltage that correspond to <10% SoC with no load, but you can also tune it to your own loads, maybe something like 22V might be better for you. This is another area where you really want a bit more intelligence in the inverter or the management system. A 24V battery sitting at 24V with a small- or no load is a bad sign, whereas the same bank sitting at 23V with a large load is not a bad sign. The voltage should be interpreted in the context of the present load. Now some inverters have something called "dynamic cut-off" that does exactly that, but it is rare :-) Chris Hobson 1 Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted July 4, 2017 Share Posted July 4, 2017 7 hours ago, Leondk said: Chris, i see that you also have the Axpert Inverter, could you maybe shed some light, when i am running on battieries alone the system gives me a low voltage warning on 24,5volt but on the axpert it is set to only cut out on 24volt. so according to the previous answers here there is still plenty of power left in the batteries. Is there something i am missing or should i just set the cutout voltage to 23.5? i am not so keen on that because i don't want to ruin my very expensive investment in batteries Plonky has basically covered what there is to say it is a pre-alarm feature. I use a BMV to cut the load as the Axpert's SOC is useless. Quote Link to comment Share on other sites More sharing options...
Sass Posted November 4, 2019 Share Posted November 4, 2019 Maybe Chris can help me here My inverter will not power up I have an Axpert MKS 5KVA inverter. The system runs on 2 strings of 325W panels. Presently my PV supply measures 83V. Battery voltage is at 50.1V and it's a 48V battery system Open circuit voltage is spot on within the manual specification and I have checked everything. It has been running seamlessly since April. and this morning it started a scheduled battery equalisation I was working in my workshop when the power went off. I checked everything and noticed that the inverter will not switch on at all. I am presently running on grid power, and would like to know if there is any way to determine if the inverter has packed up? The supplier is shrugging me off as they did not do the installation. This is of course a huge frustration to me and I will not open the inverter, breaking the seal as this inverter is stuill under warranty What can I do to check if all is well and diagnose the problem? Thank you Sass Quote Link to comment Share on other sites More sharing options...
Coulomb Posted November 4, 2019 Share Posted November 4, 2019 17 minutes ago, Sass said: My inverter will not power up So when battery is connected, there is no twitching of the fans? Light from the LC Display or any segments visible? Any of the LEDs come on? A beep? Any difference if there is a charging source, i.e. PV or AC in? The 50.1 V is measured at the inverter battery terminals? (Thus eliminating any battery wiring or fuse/breaker issue.) If there is no life at all (fans, LEDs, LC Display, or beep) when there is 50.1 V at the battery terminals, then that's pretty much the sign that the inverter-charger is dead. Is there a faint smell of burned components? Starting the equalisation means that the battery voltage would have gone up higher than usual, and that brings the components closer to their limits. Quote Link to comment Share on other sites More sharing options...
3kw inverter Posted February 10, 2020 Share Posted February 10, 2020 Hi, i have a 3kw 48v mecer with 120A Omnipower batteries. My issue is that whenever the power cuts off and i draw less then +- 60W my inverter doesnt give me 220v. seem like it goes into sleep mode because if i draw more wattage the 220v is back and all normal. Quote Link to comment Share on other sites More sharing options...
Coulomb Posted February 11, 2020 Share Posted February 11, 2020 8 hours ago, 3kw inverter said: seem like it goes into sleep mode Seems like it might be in power saving mode; check setting 04 (Power saving enable/disable). I find this "feature" a nuisance, so I always disable it (SdS option). Quote Link to comment Share on other sites More sharing options...
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