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Axpert 5kva x 2 Parellel Connection Setup for Gel Batteries


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Posted (edited)

Hi,

I'm new to the forum, but been looking through it for a while. 

I have recently had 2 x Axpert 5kVa Hybrid Solar Inverters installed in parallel with 8 x 12v 200ah Gel batteries in a parallel series connection to total 48v 400ah. The system is only for backup and load shedding so no PV's installed as yet (long term project).

1st Question:

I would like to ask if anyone can give me the correct settings for the batteries on the system. I scrounged around different forums and managed to find something that could work with the following settings:

01 - Uti (Discharge Priority)

02 - 50A (Total Charge Current)

05 USE (Battery Type)

12 - 49.0V (Back to Utility)

13 - 54V (Back to Battery)

16 - CUt

26 - 56.4V (Charge Voltage)

27 - 55.2V (Floating Voltage)

29 - 48V (Battery Cut-off)

Not sure if this will work, but anyone with a similair setup that could give me some useful info to get my setup correct would be most appreciated.

2nd Question:

The fans run continuously - with big loads or almost no loads. Is this normal?

Many thanks!

Edited by Bean
Posted
On 2022/04/02 at 9:41 PM, Bean said:

02 - 50A (Total Charge Current)

That's 100A total (50 A per inverter). That's 0.25C, which is on the high side. Most lead acid is 0.15-0.2C. But it depends on your battery. Does it have a recommended maximum charge current? It's often printed on the side of the battery modules.

On 2022/04/02 at 9:41 PM, Bean said:

27 - 55.2V (Floating Voltage)

Generally lead acid is float at between 13.5 and 13.8 V per nominally 12 V module. Your 55.2 V figure is right at the top end of this range. In hotter climates, it should be towards the lower end of this range. Consider 13.6 x 4 = 54.4 V. Better yet, it should be temperature compensated, but these inverters don't offer that facility.

On 2022/04/02 at 9:41 PM, Bean said:

The fans run continuously - with big loads or almost no loads. Is this normal?

It's normal for the fans to be turning all the time, yes. But they should be running at 30% PWM when idle or at night unless the load is very high, and that should be barely noticeable. Of course, if you install two inverters in your bedroom, you will certainly notice them.

Posted (edited)

Hi Coulomb,

I’m really quite clueless when it comes to this stuff.

I did find an info sheet on the side of the battery that was hidden by the installer (who clearly knew how to install but didn’t know how to set up correctly).

I’ve included it below. Any info you can help with would be greatly appreciated!

1 hour ago, Coulomb said:

That's 100A total (50 A per inverter). That's 0.25C, which is on the high side. Most lead acid is 0.15-0.2C. But it depends on your battery. Does it have a recommended maximum charge current? It's often printed on the side of the battery modules.

I’ve changed setting 02 to 10A on each inverter which has stopped the fans running continuously. Is this ok to charge up between Load Shedding or should I rather keep it at 20A?

1 hour ago, Coulomb said:

Generally lead acid is float at between 13.5 and 13.8 V per nominally 12 V module. Your 55.2 V figure is right at the top end of this range. In hotter climates, it should be towards the lower end of this range. Consider 13.6 x 4 = 54.4 V. Better yet, it should be temperature compensated, but these inverters don't offer that facility.

I take it Gel and AGM can be seen as the same type of battery? I’ll make the change on 27 to 54.4V , but please could you see what you think of the info from the sticker I posted below and let me know if it’s correct?

Thanks again for the help!

38C586DD-46E6-4F59-9F45-695488A849A3.jpeg

Edited by Bean
Posted
12 hours ago, Bean said:

I did find an info sheet on the side of the battery ... I’ve included it below.

Unfortunately, the maximum charging current isn't on that label.

12 hours ago, Bean said:

I’ve changed setting 02 to 10A on each inverter which has stopped the fans running continuously. Is this ok to charge up between Load Shedding or should I rather keep it at 20A?

10 A (20 A total) is quite slow, but if you can recharge the battery before the next load shed, that's fine for now.

0.15C x 400 Ah = 60 A, so I would set them to 30 A each, unless you can find a higher maximum charge rate on the battery manufacturer's web site.

12 hours ago, Bean said:

I take it Gel and AGM can be seen as the same type of battery?

For the purposes of charging, sealed AGM is regarded as the same as gel, yes, unless the battery sticker indicates anything special. Yours don't indicate anything special.

It's amusing how they screwed up the temperature values on the label, at least twice.

Posted

Hi

I hope none of my suggestions contradict @Coulomb - He is the expert with the Axpert :) However I would like to share my expertise with a very similar setup and propose some slight modifications.

1. Setting 02 - With your batteries, I would say 20A is sufficient if just dealing with SA Load shedding. Gel is slightly/similar in characteristics to the older Lead/Crystal (battery motors, alarm batteries, etc), but it need a lot more current before trying to boil the battery insides. This is based on the fact that you have 2 banks of 48V 200Ah. This is close to Coulomb settings, but might prevent premature expiry of the batteries by charging them slower.

2.  Setting 26 - 100% agree with temp issue raised above, however due to way most invertors work they generally don't use this kind of setting often (although the Axpert does get a bit more aggressive - too often).  Batteries need occasionally  to be charged at slightly higher rates/voltages than normal - My thoughts that once a month is sufficient, but this is my opinion. The reason is to remove certain buildup within the battery and improve performance. I would leave this setting close to 57.4VDC for standard Lead batteries, but can go up to 58.8.

3. Setting 27 - That is far too high for an Axpert with ANY batteries - Float should always be between 12.5 and 14.4 per battery, no matter what type used. 12.5 is far too low and will eventually allow "crud" to form inside batteries, needing the 26 setting above. But setting too high (near 15V) will just keep boiling the battery and possibly start a fire if you get a slightly compromised cell... Keep this closer to a reasonable voltage like 13.5VDC per batt (or 52-54 VDC on the Axpert)

4. Setting 29 - 48 to 49VDC is reasonable if you want to keep your batteries safe. Mine were set to 50, but a sudden draw would trip the Axpert, so eventually set to 48.

5. Setting 13 - Nobody can advise you on this one - It is just experience in your environment. Just make sure this setting is not lower than setting 27 (1/2 a volt below) or you will get unexpected hops between power/non-power modes.

I prefer charging slower and not pressurising my batteries, they are very expensive to replace. I had a similar setup to yours, but used cheap batteries and nearly burn't my house down. Batteries are almost the most important part of your system, they have to be able to store the power you need, but also need to last. No matter the tech, if you abuse the batteries, you will have an expensive trip into solar. I have made one or 2 of my solar battery setups last 15years and still working with same Lead Acid, but it needs care.

So, take care of the batteries and get decent or maintain the ones you have. All settings on the Axpert, or any other invertor, need to take care of this... Invertors and Panels are relatively cheap, batteries aren't.

 

Posted

Thanks so much for the feedback @Coulomband @KLEVA. Very helpful indeed! 

I will adjust my setup accordingly and hopefully get the best out of my batteries and the setup as a whole!!

  • 1 month later...
Posted

As an aside - Nothing to do with advise above...

Due to the floods and lack of power in Pinetown for days, I thought I would put my batteries under bit of pressure for a day or 3... Big mistake - I had the optimal and thought I could do better... Popped 5/8 of my 200Ah AGM batteries by dropping too low and then overcharging - Took a possible 20yr set of of AGMs down to 3 years lifespan, now they are F#$%^&*

PS: KLEVA is now trying to find 9kW+ LiPO batteries😒

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