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Axpert 5kv 48v Question


Mark
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I have just installed the inverter and am loving it... can someone help with the voltage for setting return to battery from utility. I have set it to full but was keen to know this voltage. 56?

Thanks

Mark

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  • 6 months later...

.. can someone help with the voltage for setting return to battery from utility. I have set it to full but was keen to know this voltage. 56?

Sorry for the late reply, but I thought I'd answer this question since I have a bit of a unique insight into the firmware, and others may want to know the same thing. It's not terribly clear in the manual.

 

Parameter setting number 13 ("back to battery mode") seems to be about terminating the bulk/absorb stage of a utility charge early when the battery reaches a certain voltage. This might be because you are using the utility as a "last resort" or "most expensive, use last" option for charging the battery. You would prefer to use solar, but sometimes there just isn't enough. When there isn't enough solar energy available, parameter 12 will have initiated a utility charge to prevent the battery voltage (and hence rough SOC) from falling below a certain level. Parameter 13 is about when to stop doing that utility charging.

 

When the utility charge gets the battery to the voltage in setting 13, the utility charger goes to the float stage, meaning it will not cost you much money now, you're just maintaining the float voltage.

 

So the "FUL" setting in parameter 13 means don't terminate the charge early; continue in bulk and absorb until the charge would normally terminate, i.e. when the battery is full. So effectively, this is like choosing your CV setting; that's the voltage where the absorb stage would stop and float would start. But with a normal charge (setting 13 = FUL), the utility charge won't stop as soon as it hits the CV voltage; it will start an absorb stage where the CV voltage is maintained until the charge current falls to a low value. So in that sense, FUL doesn't correspond exactly to a fixed voltage setting.

 

Internally, the effect of the FUL setting is to make the "back from weak battery" voltage equal to 100.0 V; the battery will never reach 100 V. In other words, if the battery is declared weak (that means that utility charging is turned on where possible), it is never declared non-weak. So that means that the utility charge is never forced from bulk/absorb to float before the normal charge has completed. So in that sense, FUL is equivalent to 100 V.

 

I believe that this has no relevance when using Uti as the Output Source Priority (parameter setting 1). You would use Uti output source priority for an off-grid installation. They (settings 12 and 13) make most sense to me when using SbU as the output source priority (i.e. Solar first, battery next and Utility as a last resort).

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  • 10 months later...

Hi All

Does anyone known if there is a loss when the Axpert is in Bypass (UTL) Mode, and if so the %?   I know the charging of the batteries has losses, but when they are charged and the inverter is pretty much just running the loads?

Thanks

Mark

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Howzid Mark.  

If you log the units used at your meter from the grid against the units through the inverter it should give you an idea. In my case whenever I had to start the genny the Inverter "let" the gennys power straight though so to speak as I could see the Htz and the voltage fluctuate as it is the norm with smaller gennies . So I would guess that there should be minimal losses.

Regards

Paul 

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  • 1 month later...

Hi all I saw this was an Axpert related topic so thought I would try and post here rather than starting a new thread.  I have three Axperts (5kVA) running in parallel for a nice 15kVA single phase setup.  Everything is 100% but there is this one thing that I cannot get right.

It is a totally off grid system, so it does happen from time to time that the cut-off voltage is reached and that the inverters switch off (as they should).  The next day they start charging again (the MPPT never switches off) but they never switch on again, only the MPPTS work as expected but when reaching the top value of the battery voltage range they do not switch the AC back on as they should.  I have tested in on another setup and it does switch back on in that setup (only one inverter though).

Anyone had this before?

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On 12/4/2016 at 6:31 PM, Mark said:

Hi All

Does anyone known if there is a loss when the Axpert is in Bypass (UTL) Mode, and if so the %?   I know the charging of the batteries has losses, but when they are charged and the inverter is pretty much just running the loads?

Thanks

Mark

Hi Mark, the Axperts need about 70 - 80W from the battery bank even in bypass mode.  The inverter internal electronics are powered from the DC bus.  In terms of losses on the AC side it should not be but I have not measured that to prove it. Unfortunately it is a little high and has a material effect on a small to moderate size battery bank, especially if you have 2 or 3 inverters.

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