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MUST and SUNX charging time


skai

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I have a Must (Axpert) 3KVA inverter and a SunX (Hubble AM-4) 2.6kw 100Ah 2400Wh lithium battery. I am not using Solar - just battery backup for loadshedding.

My inverter settings as follows:
11    Maximum Charging Current                       80
13    Maximum Utility Charging Current            30
14    Battery Type                                               USE
17    Bulk Charging Voltage (C.V Voltage)        29.2
18    Floating Charging Voltage                         29.0
19    Low DC Cut Off Battery Voltage Setting  24
20    Battery stop discharging voltage when grid is available    26.5
21    Battery stop charging voltage when grid is available          29

The battery takes almost 5 hours for a full charge after 4-4.5 hour loadshedding. From full, the battery drains to below 20% during a 4-4.5 hour loadshedding. From what I understand, the battery should charge to full in much less time than the almost 5 hours. Are there settings I can change to charge the battery quicker - or does the 5 hours charge time seem right/reasonable? Problem is that with stage 6 loadshedding, we often have 2 back-to-back 4.5 hour outages with only a 4 hour window to recharge the battery.

Would appreciate any guidance on this matter.
 

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6 minutes ago, meetyg said:

Is 30 amps the maximum utility charging current you can set?

Why not try 50 amps to see if it helps?

These inverters were designed for lead acid. Pushing 50A into a 12V 100Ah you are putting yourself in a position by choice to buy new batteries within 9 months. 

Yes different for lithium if it within specs. 50A is quite a bit. I have my lithiums set to 20A per parallel bank. 

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9 minutes ago, Scorp007 said:

These inverters were designed for lead acid. Pushing 50A into a 12V 100Ah you are putting yourself in a position by choice to buy new batteries within 9 months. 

Yes different for lithium if it within specs. 50A is quite a bit. I have my lithiums set to 20A per parallel bank. 

Lithium batteries can easily handle a 0.5C rate charging. Most state a maximum C rate of 1 or sometimes even more.

As for degradation, I don't think the difference between 0.2C and 0.5C will do noticeable damage. Maybe if you charge at 1C or higher constantly, that may affect the cycle life.

But for a 100Ah Lithium battery, 50A should be fine.

In any case, it was just a temporary suggestion, to see if the charging rate is the problem or something else.

Edited by meetyg
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25 minutes ago, Scorp007 said:

These inverters were designed for lead acid. Pushing 50A into a 12V 100Ah you are putting yourself in a position by choice to buy new batteries within 9 months. 

Only Victron seems mad enough to make 3 and 5KVA inverters that run from 12V.  The MUST 3KVA inverter runs from 24V.

@skaiThe 30A is the recommended charging rate for the Hubble AM4.  The maximum continues charging rate is given as 115A, so you could increase it to 50A without concern.

Note that  <17>  Bulk Charging Voltage (C.V Voltage)   =  29.2  is a bit high.  According to Hubble this should be 29V.  See the summary here: https://www.hubblelithium.co.za/axpert

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5 hours ago, skai said:

I have a Must (Axpert) 3KVA inverter and a SunX (Hubble AM-4) 2.6kw 100Ah 2400Wh lithium battery. I am not using Solar - just battery backup for loadshedding.

My inverter settings as follows:
11    Maximum Charging Current                       80
13    Maximum Utility Charging Current            30
14    Battery Type                                               USE
17    Bulk Charging Voltage (C.V Voltage)        29.2
18    Floating Charging Voltage                         29.0
19    Low DC Cut Off Battery Voltage Setting  24
20    Battery stop discharging voltage when grid is available    26.5
21    Battery stop charging voltage when grid is available          29

The battery takes almost 5 hours for a full charge after 4-4.5 hour loadshedding. From full, the battery drains to below 20% during a 4-4.5 hour loadshedding. From what I understand, the battery should charge to full in much less time than the almost 5 hours. Are there settings I can change to charge the battery quicker - or does the 5 hours charge time seem right/reasonable? Problem is that with stage 6 loadshedding, we often have 2 back-to-back 4.5 hour outages with only a 4 hour window to recharge the battery.

Would appreciate any guidance on this matter.
 

This seems to be the down side of using voltage to charge. How do you in fact know they are fully charged. 

I have found my Hubble can stand very long on the same voltage before the current drops very low. Also using voltage on an Axpert. 

Also the battery indicator does not help to give a SOC. 

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1 hour ago, Scorp007 said:

This seems to be the down side of using voltage to charge. How do you in fact know they are fully charged. 

I have found my Hubble can stand very long on the same voltage before the current drops very low. Also using voltage on an Axpert. 

Also the battery indicator does not help to give a SOC. 

I am still learning....   The way I understand it, only the Axperts with removable LCD and the new round LCD displays can communicate with a battery's BMS.  Is that correct?  So for anyone running an older Axpert the above is a given.

I initially presumed that the Hubbles are LiFePO4, but even that seems incorrect.  The high bulk charge voltage is a hint to that.  Further irritation is the requirement for the cloud interface that costs 3K just to know how the battery feels.  So at the moment I am operating in the dark iro battery SOC, cycle counter, etc.

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On 2023/04/24 at 9:55 AM, skai said:

@meetygPV18-3024VPM - I am not sure what Pylontech is but will do some research on this...thank you

 

 

Pylontech is a company that makes batteries, but thier communication protocol is considered somewhat if an industry standard for battery communications. 

Your model seems to be fairly recent, so I think it should support the protocol.

The question that remains is: do the batteries you have support this protocol.

 

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The inverter manual indicates that COM (port 12) is for RS-485 communication and the battery has 3 ports for RS485 (CAN, A and B). Does this mean I use the supplied cable to connect the inverter to the battery - and if so, to which RS485 port on the battery? Will other settings need to be changed as well? Also noteworthy is that on battery type setting 14 on the inverter - I do not have the option of PYL as indicated in some of the (google!) research I have done.

 

Inverter Battery Bottom View.jpeg

Inverter Port Description.jpeg

Inverter Side View.jpeg

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As for the inverter, the COM port actually has RS485 and CAN lines.

SmartSelect_20230502-151647_SamsungNotes.jpg.2f4db822662399acb8c290ec4e7328a7.jpg

You might need to crimp your own RJ45 cable, using only CANL, CANH and GND.

As for the battery, I really don't know where its supposed to connect.

Maybe you can refer to its documentation, or get help from someone with a similar battery.

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