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Macduffy

Inverter Settings and Questions

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Hi there

I have installed a UPS system at home due to loadshedding and periodic and occasionally regular electricity supply failures from Eskom. The loadshedding is 2 hours at a time and generally not more than 4 hours in a day, and our power failures on average are resolved within 4 hours (rarely going above 8 hours). I am essentially looking for 600Wh to 800Wh of power in which I can run my alarm system, gate motor, TV, lighting, Wifi, laptop and phone chargers (not all at once). I typically manage the load when the power is off and try not to exceed 150W for loadshedding and 80W for power failures where the outage time is unknown.  

To meet the above requirements I installed the back up system in April 2018 with a FullCircleSolar 1kVA/1kW inverter (FCS-1K-VP-1000W) (I understand that this is Voltronic?); and 2 x Omnipower AGM 120ah (OPR-120) (datasheet here OmniPower_OPR120_Datasheet.pdf) batteries . The system was designed on running to between 30% and 50% DOD. There are no solar panels connected to the system and it is installed in an enclosed room in my house (temp 15 - 25 dec C). At the time I had little to no knowledge of inverters/batteries, and kept the default settings on the inverter (AGM charge settings and a DC cut off of 10.5V). After 14 months of operation, and approximately 40 power outages, the batteries started to lose capacity, I didn't track to voltage too closely but they likely discharged as low as 11.3V for 2 or 3 times (a few prolonged outages).  I guess I took the battery data sheet a bit too literally - I thought I could run them to 80% DOD and get 1000 cycles... Eventually the batteries would charge to the float voltage but when discharged they only lasted 60min on around 20W power draw until error 04 would be displayed and it shut off, that said, when I disconnected the charged batteries and left them for 24 hours they read a voltage of 12.8V. Based on what I read on this forum the above means the batteries are toast.?..?.

I have since replaced the Omnipower batteries with 2 x Ritar DC12-100 AGM (datasheet here DC12-100.pdf) batteries from Mantech, I read generally positive reviews about these batteries and they are well priced. I am aiming to get 5 years out of the batteries so I am now extra cautious and have the following settings on the inverter:

Program Description Selectable option
01 Output source priority Ut1
02 Maximum charging current 30A
03 AC input voltage range UPS
05 Battery type USE
06 Auto restart when overload occurs Restart disable
07 Auto restart when over temperature occurs Restart disable
09 Output frequency 50Hz
11 Maximum utility charging current 20A
12 Setting voltage point back to utility source 11.5
13 Setting voltage point back to battery mode 13.5
16 Charger source priority CUt
18 Alarm control bON
19 Auto return to default display screen ESP
20 Backlight control LON
22 Beeps while primary source is interrupted AON
23 Overload bypass Disable
25 Record fault mode FEN
26 Bulk charging voltage 14.7
27 Floating charging voltage 13.7
29 Low DC cut-off voltage 12.0V
30 Battery equalisation Disable
31 Battery equalisation voltage 14.6V
33 Battery equalised time 60
34 Battery equalised timeout 120
35 Equalisation interval 30d
36 Equalisation activated immediately Disable

Are these settings correct for the given battery?

I am also paying closer attention to the discharge/charge cycle of the batteries, and I am concerned that the inverter is skipping the absorb stage of the charge cycle (referred to elsewhere in the forum as premature float bug with the Axpert inverters). The below is a discharge/charge cycle for a recent loadshed, and when charging it goes directly to the float voltage of 13.7V. 

image.png.0d9f8870779a5e168f266d6d3e0df208.png

The full excel sheet for this cycle is here 20200211211115.xls

Is this what I think it is, is the absorb stage being skipped and the batteries only partially charged, could this be partly responsible for the demise of my previous Omnipower batteries? Alternatively am I not discharging the batteries enough to trigger the absorption stage? I am concerned I am going to destroy these Ritar batteries as well. Should I try and update the firmware and also risk bricking the inverter, my version is U1.08.33? Also I saw on another thread that someone has sort of overcome premature float problem by activating the equalisation setting for the AGMs - 2 days a week at 14.3V for 120minutes. Is this a better solution or can I damage my AGMs from this? 

The is what the manual states the charging cycle for the inverter should follow the below:

image.png.f1b2a56a91612118872b06297b6940eb.png

Another question on the active power and the apparent power, my understanding is that the ratio of these two gives the power factor. In some instances it goes above 2, which you will see on the raw data I attached above. However, when I unplug my gate motor and alarm it goes down to 1. Is there anything that can be done to correct this, or is it just "it is what it is"?

Thanks

Liam

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17 hours ago, Macduffy said:

I installed the back up system in April 2018 with a FullCircleSolar 1kVA/1kW inverter (FCS-1K-VP-1000W) (I understand that this is Voltronic?)

Yes. I believe it's an Axpert VP1000-12. With PWM solar charge controller, not that you care about that at this stage.

17 hours ago, Macduffy said:

Eventually the batteries would charge to the float voltage but when discharged they only lasted 60min on around 20W power draw until error 04 would be displayed and it shut off, that said, when I disconnected the charged batteries and left them for 24 hours they read a voltage of 12.8V. Based on what I read on this forum the above means the batteries are toast.?..?.

They're showing about 2 Ah capacity (combined). So yes, toast. So they were only ever charging to the float voltage (mid 13s), not the absorb voltage (mid 14s)?

17 hours ago, Macduffy said:

have the following settings on the inverter:

They seem OK. I note that setting 11 will effectively be 12.5 V, but since you have only one source of power at present, that doesn't matter. I note that the charge voltages are for 25°C, and should be reduced if the battery gets hot. But you say that they are inside where it should not get hot, so that's fine.

17 hours ago, Macduffy said:

The below is a discharge/charge cycle for a recent loadshed, and when charging it goes directly to the float voltage of 13.7V. 

That's certainly not good. It's a classic case of the premature float bug. It's usually not so blatant, but when utility charging, it will be either as bad as this, or work correctly, nothing in between.

17 hours ago, Macduffy said:

Is this what I think it is, is the absorb stage being skipped and the batteries only partially charged, could this be partly responsible for the demise of my previous Omnipower batteries?

It sure looks like it.

17 hours ago, Macduffy said:

Alternatively am I not discharging the batteries enough to trigger the absorption stage?

That's an excellent question. Or rather, are you discharging the batteries enough to exit the float stage? You should watch closely the charge LED (probably the middle one, probably green). Off = no charge, flashing = bulk/absorb charge, on = float. As long as the LED goes off before the start of the charge, you should get a bulk then an absorb stage (both with the flashing light). I suspect you're getting off, then a minute or two of flashing, then on. You should get hours of flashing (proper charging, assuming the battery need it), followed by a long period of the charge LED on solid.

The time when the battery stays around 12.7 V sounds like it's not charging. Would this have been a load shed? It appears to be about an hour. I'm not familiar with UPS operation, where you are presumably always utility charging.

17 hours ago, Macduffy said:

Should I try and update the firmware and also risk bricking the inverter, my version is U1.08.33?

I don't believe that you'll be able to find a suitable update. Besides that, Axperts have had charging issues from day one to the present.

17 hours ago, Macduffy said:

I saw on another thread that someone has sort of overcome premature float problem by activating the equalisation setting for the AGMs - 2 days a week at 14.3V for 120minutes.

That sounds like a good backup plan.

Quote

Is this a better solution or can I damage my AGMs from this?

It's not ideal. It should be possible to make it behave. So only do this if you can't find a better way. AGMs are still sealed batteries, and while 14.3 V is below the gassing voltage (14.4 V), my understanding is that you could still overcharge them.

Here's something crazy to try: change setting 02 to 20 A. Your battery (2 modules) is capable of 30 A, but your inverter-charger can only charge at 20 A, so this won't limit your charging (unless you add panels at some point). That figure (setting 02) is probably used internally to determine when the battery is fully charged, and it might be enough to trigger a proper bulk and absorb charge.

17 hours ago, Macduffy said:

The is what the manual states the charging cycle for the inverter should follow the below:

I note that this diagram is pasted from who knows where, and is largely generic and/or fiction. In particular, the very small print about the length of time in the absorb stage is nothing to do with the Axpert models. Voltronic make a lot of gear apart from Axpert inverter-chargers.

18 hours ago, Macduffy said:

Another question on the active power and the apparent power, my understanding is that the ratio of these two gives the power factor. In some instances it goes above 2, which you will see on the raw data I attached above. However, when I unplug my gate motor and alarm it goes down to 1. Is there anything that can be done to correct this, or is it just "it is what it is"?

The latter; the power factor of your load is what it is. The power factor is the active power divided by the apparent power; ideally it is 1.0, for you it goes as low as under 0.5. Any attempt to "fix it" will probably just make things worse.

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7 hours ago, Coulomb said:

They're showing about 2 Ah capacity (combined). So yes, toast. So they were only ever charging to the float voltage (mid 13s), not the absorb voltage (mid 14s)?

I didn't pay too much attention to the charging cycle on the previous batteries. I only monitored the voltage during discharge, so I cant confirm if it ever reached absorb voltage. 

 

7 hours ago, Coulomb said:

The time when the battery stays around 12.7 V sounds like it's not charging. Would this have been a load shed? It appears to be about an hour. I'm not familiar with UPS operation, where you are presumably always utility charging.

Yes, that happened was over a 1 hour loadshed. The inverter is plugged directly into a plug socket running on mains/Eskom. 

 

8 hours ago, Coulomb said:

Here's something crazy to try: change setting 02 to 20 A. Your battery (2 modules) is capable of 30 A, but your inverter-charger can only charge at 20 A, so this won't limit your charging (unless you add panels at some point). That figure (setting 02) is probably used internally to determine when the battery is fully charged, and it might be enough to trigger a proper bulk and absorb charge.

 I changed setting 02 to 20A, I then unplugged the inverter from the wall to test it on another discharge/charge cycle. At this stage the charge light turned off. I drew a more or less constant load of 100W (active power) over a 2.5hour period. The discharge current from the batteries was more or less constant at 10A over this period, so i estimate I drew ~25Ah. The batteries ran down to around 12.4V, and then I switched the power supply to the inverter back on which started the charging cycle. The charge light started flashing and the voltage went back up to 13.8V within 43 minutes, the inverter then switched straight to float mode and the charge light stayed on constantly. It seems to have once again skipped the absorb stage. The discharge/charge cycle is shown below, raw data is here 20200214222155.xls

image.png.66fbe9ba9bdafeb92796396d0ffca688.png

 

Would changing setting 16 from SNU (Solar and Utility) to CUt (Utility only) make any difference and maybe initiate the absorb charge? 

 

Thanks for your time.

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On 2020/02/15 at 7:23 AM, Macduffy said:

I changed setting 02 to 20A, I then unplugged the inverter from the wall to test it on another discharge/charge cycle. At this stage the charge light turned off. I drew a more or less constant load of 100W (active power) over a 2.5hour period. The discharge current from the batteries was more or less constant at 10A over this period, so i estimate I drew ~25Ah. The batteries ran down to around 12.4V, and then I switched the power supply to the inverter back on which started the charging cycle. The charge light started flashing and the voltage went back up to 13.8V within 43 minutes, the inverter then switched straight to float mode and the charge light stayed on constantly. It seems to have once again skipped the absorb stage. 

So... 25 Ah out, and assuming a constant charge current of 20 A (I note that the charge current reports zero the whole time), so that's about 43/60 x 20 = 14.3 Ah in (neglecting losses, of which there will be plenty). So yes, it's definitely not charging the battery.

Here are the anomalies that I see:

  • The charge current reports as 0. Surely utility charge current counts as charge current.
  • The discharge current reports as around 10 A. Yet the battery voltage is rising higher than 13 V, so it's definitely charging. I would expect to see around 10 A of charge current (20 A from the utility charge, less 10 A to the load)., [ Edit: duh! I was thinking battery mode. See post after next. ]
  • It should get to within about 0.1 V of the absorb voltage before it exits bulk stage. Yet the battery voltage never reaches that high. It seems inconceivable that it would surge that high between 30 second samples.
  • Despite the utility charge current of 20 A (presumed), it exits absorb stage immediately. (It should not even be in absorb stage anyway, as per the above). I expect that the charge current should have to fall below 4 A (20 A in setting 02 divided by 5) before it exits absorb mode.
  • Between absorb and float, the battery voltage drops significantly (about 13.8 to 13.6 V). So the charge current seems to be reduced. This is despite the load current (as seen by the battery) dropping from around 10 A to zero, so I would expect the current into the battery to double from 10 A to 20 A.
  • The battery voltage continues to rise in float mode from 13.6 to around 13.7 V. (I wonder what happens after that; presumably the battery voltage levels off at around 13.7 V). So the battery continues charging in float mode. In float mode, it will presumably take a very long time to charge.

 

I wonder what sets the charge light off in the first place. My understanding is that the battery voltage has to see a significant drop in battery voltage. Does it stay with the light off for only a minute or two?

Here is a thought. Maybe the zero indicated charge current is a serious fault, not an annoying oversight. In other words, the charge algorithm might actually believe the charge current to be zero. So zero is always less than 4, so as soon as bulk stage is over, it will qualify for going to float immediately, and spend essentially zero time in absorb mode. But that doesn't explain all of it; it should be charging to at least 14.6 V (or thereabouts) to exit bulk stage.

What happens if you increase setting 26 (bulk/absorb voltage)? For example, if you repeat the experiment (perhaps just 30 minutes of "load shed" time would be enough, or even less) with setting 26 at say 15.0 V (will it go that high?), will the bulk stage then end 0.3 V higher, at 14.1 V? That's still nothing like a full charge, but would be interesting to see if it's paying attention to setting 26 at all.

Quote

Would changing setting 16 from SNU (Solar and Utility) to CUt (Utility only) make any difference and maybe initiate the absorb charge? 

I very much doubt it. I think it's time to try the equalisation settings that you mentioned earlier. To give your battery an initial proper charge, it might be worth setting the equalisation voltage higher than 14.3 V for an hour or so. I haven't studied the equalisation firmware to see if they have charge bugs there too. One would hope not, especially since there isn't a current terminating condition. One of the charge bugs is such that it may count time near the float voltage as absorb time. 

Edited by Coulomb

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Hi Macduffy,

Very interesting discussion!

I have been involved with the inverter/battery setup on a residential estate in KZN, for a period of approx 2 years.

The estate has approx 100 households, each equipped with CB Solar 3000W (Axpert) inverter and 2 * Dixon or Enertec lead acid batteries in series (24V)

We have seen very similar results to your tests. After 2 hour load shedding, with 100W load, the inverter returns to float very quickly. On days when there are 2 load shedding outages, the batteries do not recharge properly between outages, and we have had some batteries undercharge.

We have had to recharge some batteries, and have rescued some before they suffer permanent damage.

Our biggest issue is the installer not changing the battery low voltage cutoff setting from the default of 21.0V to recommended 23.5V, this has permanently damaged several batteries.

Another issue is unequal charging of the 12V batteries in series, one battery always suffers unless a battery equaliser is installed.

Edited by Solo

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21 hours ago, Coulomb said:

The charge current reports as 0. Surely utility charge current counts as charge current.

I thought this was weird, but i assumed it related to PV current only. 

 

On 2020/02/15 at 2:29 PM, Coulomb said:

The discharge current reports as around 10 A. Yet the battery voltage is rising higher than 13 V, so it's definitely charging. I would expect to see around 10 A of charge current (20 A from the utility charge, less 10 A to the load).

I am not sure if I understand. The batteries are only in use when the mains is off, when mains is on then the batteries are bypassed and the load runs off mains power only. The batteries are only charged when mains is on, but at the same stage they have no load.  So either mains is on and the batteries are being charged (20A for bulk charge) or mains is off and the batteries have a load of 10A (or whatever my power draw happens to be) but no charge. 

 

On 2020/02/15 at 2:29 PM, Coulomb said:

I wonder what sets the charge light off in the first place. My understanding is that the battery voltage has to see a significant drop in battery voltage. Does it stay with the light off for only a minute or two?

As per above comment, the charge light comes on immediately when main is switched back on after a discharge. The charge light is only off when i switch off mains power. 

 

 

22 hours ago, Coulomb said:

The battery voltage continues to rise in float mode from 13.6 to around 13.7 V. (I wonder what happens after that; presumably the battery voltage levels off at around 13.7 V). So the battery continues charging in float mode. In float mode, it will presumably take a very long time to charge.

Yes correct, It just maintains the battery in float mode at 13.7V. 

 

22 hours ago, Coulomb said:

What happens if you increase setting 26 (bulk/absorb voltage)? For example, if you repeat the experiment (perhaps just 30 minutes of "load shed" time would be enough, or even less) with setting 26 at say 15.0 V (will it go that high?), will the bulk stage then end 0.3 V higher, at 14.1 V? That's still nothing like a full charge, but would be interesting to see if it's paying attention to setting 26 at all.

I increased the bulk charge voltage, setting 26, to 15.0V and reran the discharge/charge cycle, it made no difference and did the same as before (raw data here 20200216120042_Cycle.xls). 

image.png.ebc93f7b717a8ce19cbd69dcd1000c65.png

The bulk charge was on for roughly 22min this time with the charge light flashing, the bulk charge still ended at the 13.8V mark. The same voltage drop occurred to 13.6V at the end of the bulk charge and then it moved up to the float at 13.7V which it then maintained. So roughly 20Ah out and then ((22/60)*20) and then around 7.3 Ah back into the battery? 

I have since activated the equalisation option, this worked and brought the batteries up to 14.3V for 60min as shown below (raw data here 20200216120042_Equalise.xls)

image.png.f20e9df12bed49a701799f6b501f6749.png

I have set it to run every 4 days for now. Should I try and match the equalisation frequency to the battery cycling frequency - so after every battery discharge and charge I will then manually activate the equalisation (this may become tedious)? The problem with automating the equalisation frequency is that the power outages come in waves, we can sometimes have 3 months without any power failures and then we will unexpectedly have 15 of them in 2 weeks. An alternative approach is that I can set the equalisation setting to automatically happen once a day when we are having daily power outages and then when we are having months of no power outages I can change the equalisation frequency to once every 2 or so weeks? 

I have also placed a temperature sensor on top of the battery to better understand the temperature and variation. It consistently reads 27.5 to 30.5deg C, we are having hot days at the moment.  The battery datasheet states Equalisation and Cycle Service: 14.6 - 14.8 V @ 25dec C, should this be disregarded? You have stated that 14.4V @25deg C is the gassing temperature, so at 30 deg C it changes to ~14.3V (which is the value you said I should use above). So for the moment i will maintain the equalisation at this 14.3V for 60min periods and maybe increase the voltage slightly in winter. 

Are there any clear signs that will let me know if I am overcharging or gassing the batteries? Will the temperature of the batteries rise, or will they make a noise?   

Thanks

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On 2020/02/15 at 4:08 PM, Solo said:

Hi Macduffy,

Very interesting discussion!

I have been involved with the inverter/battery setup on a residential estate in KZN, for a period of approx 2 years.

The estate has approx 100 households, each equipped with CB Solar 3000W (Axpert) inverter and 2 * Dixon or Enertec lead acid batteries in series (24V)

We have seen very similar results to your tests. After 2 hour load shedding, with 100W load, the inverter returns to float very quickly. On days when there are 2 load shedding outages, the batteries do not recharge properly between outages, and we have had some batteries undercharge.

We have had to recharge some batteries, and have rescued some before they suffer permanent damage.

Our biggest issue is the installer not changing the battery low voltage cutoff setting from the default of 21.0V to recommended 23.5V, this has permanently damaged several batteries.

Another issue is unequal charging of the 12V batteries in series, one battery always suffers unless a battery equaliser is installed.

 

Hi Solo

This is an expensive flaw in the Axpert Inverters. I can't believe that all the Axperts have this flaw, there must be thousands of them on the market. Whats common to our systems is no solar power. My inverter, as per above, reads 0A charging current when it is in the utility charging cycle; is there a flaw that it only reads for solar charging? So when solar is connected and in use the inverter then reads this as charging current and the minimum current of 4A is achieved and the inverter can then get to the absorption stage - but as Coulomb said this still doesn't explain why it doesn't reach the bulk charge of 14.7V when on utility. 

I also got caught by the battery low cutoff setting -  battery suicide.

My batteries are in parallel so I don't get the unequal charging issue. 

 

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7 hours ago, Macduffy said:

I am not sure if I understand. The batteries are only in use when the mains is off, when mains is on then the batteries are bypassed and the load runs off mains power only.

Duh, yes. I'm so used to battery mode (my inverters are rarely in line mode) that I was thinking battery mode. Sigh. Ok, that's one anomaly down.

7 hours ago, Macduffy said:

The charge light is only off when i switch off mains power. 

Ah. Makes sense.

7 hours ago, Macduffy said:

I increased the bulk charge voltage, setting 26, to 15.0V and reran the discharge/charge cycle, it made no difference and did the same as before...

Right. So that's classic charge bug. It's using the wrong voltage setting to exit absorb mode. But exiting bulk mode too soon as well, and seems to be using the wrong terminating current criterion. That sounds like badly messed up firmware to me. If your machine is say a year old or more, have you approached your supplier to see if there is a firmware update for it?

7 hours ago, Macduffy said:

The bulk charge was on for roughly 22min this time with the charge light flashing, the bulk charge still ended at the 13.8V mark. The same voltage drop occurred to 13.6V at the end of the bulk charge and then it moved up to the float at 13.7V which it then maintained. So roughly 20Ah out and then ((22/60)*20) and then around 7.3 Ah back into the battery? 

Yes. I think that you now know a huge part of why your last battery died: chronic undercharging. That will reliably kill lead acid batteries.

7 hours ago, Macduffy said:

I have since activated the equalisation option, this worked and brought the batteries up to 14.3V for 60min as shown below...

Good to hear that that works, at least.

7 hours ago, Macduffy said:

An alternative approach is that I can set the equalisation setting to automatically happen once a day when we are having daily power outages and then when we are having months of no power outages I can change the equalisation frequency to once every 2 or so weeks? 

That sounds like the better option.

7 hours ago, Macduffy said:

I have also placed a temperature sensor on top of the battery to better understand the temperature and variation. It consistently reads 27.5 to 30.5deg C, we are having hot days at the moment.  The battery datasheet states Equalisation and Cycle Service: 14.6 - 14.8 V @ 25dec C, should this be disregarded?

If you're going to equalise potentially every day, then yes, definitely! 

Quote

You have stated that 14.4V @25deg C is the gassing temperature, so at 30 deg C it changes to ~14.3V (which is the value you said I should use above). So for the moment i will maintain the equalisation at this 14.3V for 60min periods and maybe increase the voltage slightly in winter. 

I think you should go to 14.2 V whenever the battery will see 30°C while charging. The goal is to have as high a charge voltage as possible, without gassing, so that there is no chance that the battery will lose water that you can't replace. The battery can cope with some gassing, that's why the absorb voltage is so high, but equalisation is uncontrolled; it just runs for a fixed time. A proper charger would stop the charge when the charge current falls to a certain level.

Perhaps change to 14.3 V or even 14.4 V in winter, avoiding the gassing voltage each time.

Quote

Are there any clear signs that will let me know if I am overcharging or gassing the batteries? Will the temperature of the batteries rise, or will they make a noise?   

Unfortunately, nothing really obvious. You should be able to hear a soft ticking sound when gassing; you might need a crude stethoscope to hear it. It might be worth setting something up to monitor that sound until you get a feel for when it's gassing, so you get peace of mind that you are not going to ruin your new battery (any more than it already is; hopefully the degradation will be very slight at this point).

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19 hours ago, Coulomb said:

If your machine is say a year old or more, have you approached your supplier to see if there is a firmware update for it?

I called the supplier of the inverter today, he said that setting 05 should be on AGM and not User Defined. I reran the discharge/charge cycle with setting 05 on AGM and it did the exact same as before - the bulk charge stopped at 13.8V and skipped the absorb charge. I will contact him again tomorrow to see what else he can recommend, he was quite helpful. 

 

19 hours ago, Coulomb said:

I think you should go to 14.2 V whenever the battery will see 30°C while charging.

Thanks I have set it to 14.2 V for now. 

 

19 hours ago, Coulomb said:

Unfortunately, nothing really obvious. You should be able to hear a soft ticking sound when gassing; you might need a crude stethoscope to hear it. It might be worth setting something up to monitor that sound until you get a feel for when it's gassing, so you get peace of mind that you are not going to ruin your new battery (any more than it already is; hopefully the degradation will be very slight at this point).

I will see what I can arrange to monitor them. The batteries are still very new, I have only cycled them around 2 or 3 times where they went straight to float charge. The rest of the cycles I have used the equalisation setting at the end to do the absorb charge. Hopefully no noticeable damage has been done. 

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Hi McDuffy,

How do you measure your battery voltages - external voltmeter, Axpert display, or  RS232 port and PC?

I would really like to see a comprehensive test of the Axpert performance, but using lab equipment to accurately measure volts and amps.

Not sure I trust the measurements displayed by the Axpert :)

Regards,

Solo

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1 hour ago, Solo said:

Hi McDuffy,

How do you measure your battery voltages - external voltmeter, Axpert display, or  RS232 port and PC?

I would really like to see a comprehensive test of the Axpert performance, but using lab equipment to accurately measure volts and amps.

Not sure I trust the measurements displayed by the Axpert :)

Regards,

Solo

Hi Solo

The measurements I posted are directly from the inverter, from the USB cable. I then use WatchPower to log the data. The readings on the Axpert display and the WatchPower readings should be the same. 

I have verified the Axpert display reading with a voltmeter, measured across battery terminals, and it is quite accurate - a difference in measurement +-0.05V. The Axpert reading tends to have more noise whereas the voltmeter provides a constant voltage across the batteries. 

Regards  

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Hi @Coulomb @Solo

Following your advice I contacted the South African agent and he in turn got in contact with the OEM engineer. The engineer stated that the inverter follows a 2-step charge if it is above 12V and a 3-step charge if it is below 12V. I since reran the test and dropped the batteries down to 11.9V and then started the charge cycle, it went through the bulk charge stage and stayed at the absorption voltage for a number of hours and then finally entered the float stage. So this seems to have solved my problem, I wasn't draining the batteries low enough to enter the absorption stage. I have only tested this when setting 05 is set to AGM, which the agent advised. I am still to test it under the User Defined setting. 

I don't often drop the batteries to below 12V, so I may still keep the equalisation option active every few days/weeks just below the gassing voltage. I am still concerned I am only partially charging the batteries on the 2-step charge.....

On another note I looked further into the batteries that I previously bought that went bad - the Omnipower (OPR120-12) ones which lasted just over a year. I was told that most of these are sold as new, however are actually second hand and are taken from battery banks. The guys keep the box and then repackage them. One of the signs to look for is a serial code sticker stuck to the top of the battery over the original serial number. As it turns out my Omnipower batteries has a different serial number stuck over the original serial number and some of the digits vary - so I suspect I may have been sold old batteries. The shop I bought them from has since gone out of business so no option for recourse. On my new Ritar batteries I checked the voltage when I bought then (>12.7V) and checked the date of manufacture from the serial number (Aug 2019) - hopefully it is enough of a check to ensure I bought new batteries this time. 

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