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Axpert settings


Clivevan
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Finally after almost a year of struggles my Axpert 5Kw is installed with 4x180 Omni AGM batteries (48 volt). It is to operate as a UPS only. No panels.

How do I set the Axpert to automatically cut out once the batteries have reached say 50% DOC?

I tried to understand the manual but it is Greek.

 

regards

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I would change setting 29 (low DC cutoff voltage) to 50 V. Depending on loads, it might be acceptable to use 49 V (12.25V per 12 V module). 48 V is too low in my opinion, nearly dead flat. But take into account that I'm no lead acid expert.

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If you want to do it properly, get a BMV702 (BMV 700 is slightly easier on the budget)

Wonderful little device to monitor the SOH (state of health) of your batteries, and can be set to trigger a relay or alarm at whatever DOD you set.

Otherwise what @Coulomb has suggested will work fine provided you aren't pulling big loads from the batteries which may trigger false positives when the voltage dips below the set threshold.

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OK now what?  The programme only permits a Low DC cut-off range between 40 to 48 V (ie the custom setting for setting 29;  the default is 42V!)

How can the default be so low?  Do batteries even go that low??  

What to do if I want to select eg 49V as a low cut-off voltage? Or does it not matter much and 48V is OK?

regards

 

 

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3 minutes ago, Clivevan said:

OK now what?  The programme only permits a Low DC cut-off range between 40 to 48 V (ie the custom setting for setting 29;  the default is 42V!)

Oops! I run patched LFP firmware, I forget what it's like for others. My bad.

3 minutes ago, Clivevan said:

How can the default be so low?

It was only intended as a last-resort emergency action, not an every day thing.

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Do batteries even go that low??  

Under extreme circumstances, sure. But it's not good for their long term health if it happens too often.

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What to do if I want to select eg 49V as a low cut-off voltage? Or does it not matter much and 48V is OK?

You can't. Even the lead acid flavour of patched firmware doesn't go above 48 V for this setting. So you need to find another way to achieve what you want. Which I believe is you want to turn off the loads when the battery voltage reaches a moderate SOC.

Perhaps ICC can help, though it may try to switch your inverter into line (bypass) mode, but I think that with no AC-in, it will keep running from battery.

Maybe you should consider patched firmware after all; see Can I update my firmware, and if so to what? If you can run 73.00e or 72.20e, either of those will let you set the low DC cutoff voltage to a maximum of 52.0 V. Warning: the LFP flavour is not intended for lead acid batteries, so this will not be ideal, and I haven't thought through the consequences.

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Ok - I follow. But if I should set it at 48 Volt that will equate to about 50% SOC?  Surely that is OK?  

I noticed at the ICC page the following banner:

Switch between grid and battery mode based on time setting or state of charge.

My emphasis. I assume that means that ICC can assist?

 

regards

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9 hours ago, Clivevan said:

Ok - I follow. But if I should set it at 48 Volt that will equate to about 50% SOC?  Surely that is OK?  

There seems to be disagreement. For example, from https://www.energymatters.com.au/components/battery-voltage-discharge/:

 

State of Charge Sealed or Flooded Lead Acid battery voltage Gel battery voltage AGM battery voltage
100% 12.70+ 12.85+ 12.80+
75% 12.40 12.65 12.60
50% 12.20 12.35 12.30
25% 12.00 12.00 12.00
0% 11.80 11.80 11.80

Others seem to say around 45% SOC. There is probably a large range depending on load and temperature. I guess it's better than nothing.

 

9 hours ago, Clivevan said:

Switch between grid and battery mode based on time setting or state of charge.

My emphasis. I assume that means that ICC can assist?

Not necessarily, if you don't have AC-in connected.

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