GooseD

https://www.major-tech.com/product/400a-compact-ac-dc-clamp-meter/ Sure, but I am thinking they are not charging.... I unfortunately do not have any other charger that can give the required charge current for testing.. I only have the PSS inverters... That is correct. The DC amps made sense as we know what the constant load was on the AC side - The load is always constant at our backup sites (perhaps a deviation of 1AMP on the DC side now and again)

Load was constant at 15A throughout the test. When I look at the discharge voltage specification of the Omnipowers, it seems "normal" for the voltage to stay high, and only sag at the last part. But if i discharge at 0.1C I only expect to see that sagging from 2 hours and then flat at 10 hours: Hi Coulomb, thank you for your post! I understand the batteries out there can be quite "dodgy", but to my understanding Omnipower is a reputable brand? We use them only for backup purposes, so looking at the Cycle life we expect at least 300 cycles if we were to discharge every time to 100%, and this does not happen very often. Some of the sites starting to give trouble was never brought down to 50% - It is as if with each discharge, it was never charged to full again, and then after a couple of discharges it is brought to low battery. It is worth noting: it looks like PSS cuts out on 11V under load but the Omnipower specifications states that 10.8V under load is the 100% mark. For the every now and then power interruption, even with load shedding, we do not see the use for lithium at this stage as we have a very little, constant discharge current. Capacity at this stage is more important... I am still waiting to hear from PSS in regards to this problem, could it be that they are not compatible with AGM / GEL? Or is the voltage shown in the graphs enough to charge them?

Unfortunately that jump in voltage is when I turned on the generator, load was constant at 15A at that stage. Sorry for the confusion, Example A constant draw of 5.6A @12V and Example B constant draw of 15A @24V It makes sense, but is seems like it stops taking charge way too early I only have these voltage graphs for monitoring, unfortunately no current graphs, but the current draw is constant.

Hi Jaco, Thank you for your time I hear you... But surely it cannot be that we have 6x OPR240 batteries that are faulty from manufacturing.... Example B batteries are only about 3 months old with only 3-5 cycles to about 50%... The only time they were taken down to "Low Battery" was now with my testing. And immediately it started behaving the same as the other sites. For example B Current draw was constant at 15A New test: Something I just tested now: The OPR120 battery with the PSS SH-600 was charging at about 3-4A (Where I was expecting 20A) and I then added a CTEK MXS 5.0 to the mix on AGM mode. It immediately took the voltage higher up to ~14.9 from the original 13.8V that the PSS provided on charging. The CTEK stated charging at 4-5A while the PSS stopped its charging. Here is the voltage graph for this scenario:

Good day all! Thank you very much for reading this - I really hope I can get some insight as to the problems we are experiencing.... We have multiple sites running with PSS SH-series inverters (http://pss.co.za/wp-content/uploads/2017/06/PSS-Distributors-SH-Series-Inverter-Brochure.pdf) together with Omnipower OPR batteries. When we install the system, we test current draw to estimate backup time. Example A: For example we have a site with a PSS SH-600 inverter and one Omnipower OPR120 battery. We set the charging of the inverter to 20A as per battery specification. We have a current draw of 5.56A from the battery during power outage, and this estimates at least 10-15hours backup time - and it works nice at first. But after the batteries reaches it's first "Low battery" state, it seems like it never charges to full again. We can confirm that the inverter switches off at 11V and this dictates a flat battery if we look at the specifications. This site was left on "charge" for 36hours, and this was the discharge voltage graph - it only lasted 1hour15mins before it had low battery shutdown: We are experiencing failure of these combinations one after another, and most sites are not even 1 year old. We are not getting any reliable assistance from the suppliers so far - with only a confirmation that the "PSS inverters and omnipower batteries are compatible". Example B Another example is with a PSS SH-2000 inverter and 2x Omnipower OPR240 (to get the 24V needed) - and I used this to test my theory of the charging problem. This setup has a current draw of 15A when there is a power outage. I have started measuring voltage and charge current just after the low battery alarm started on the inverter: time voltage current 19:39:00 22,8 -15 low batt alarm starts 19:41:00 27,1 24,5 charging begins 19:43:00 27,3 25 19:46:00 27,2 26 19:53:00 27,2 29,5 20:00:00 27,4 29 20:05:00 27,2 30,5 20:10:00 27,5 28,8 20:18:00 27,4 29 20:30:00 27,8 29,6 20:40:00 27,9 29,1 20:50:00 28,5 27 20:55:00 27,7 15 bulk stopped as soon as voltage spiked to 29V - but this seems to soon as we expect bulk charging up to 85% capacity? 21:00:00 27,8 13 21:07:00 27,8 12 21:15:00 27,9 11 21:20:00 27,8 10 21:35:00 27,8 7 21:45:00 27,8 7 21:55:00 27,9 6,5 22:05:00 27,9 6 22:45:00 27,8 4 07:45:00 27,9 2 Voltage graph of charging: After the batteries was left on "charge" for 19 hours, we had a power interruption and this is the discharge voltage graph: Discharge amps was constant 15A and these are 200ah batteries. We expect 9-11 hours out of them, but got a low battery alarm only after 2 hours... Please any assistance / ideas will be greatly appreciated... Thank you very much!