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Parallel Axpert 5k Cut-off Configuration


fluffypony
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Hi all. My setup is as follows:

2x Axpert 5k inverters in parallel

16x Energizer / Deltec 105Ah deep-cycle 12V batteries

12x ARTsolar 60 255Wp panels

 

I'm really struggling to find the right settings for the battery cut-off voltages and, I guess, the charge priority as well. I want to maximise the power that we have to at least somewhat reduce our electricity bill, but I also want to there to be a reasonable amount of reserve power in case of load shedding or a power outage or something. I've noticed that when the batteries are fully charged they measure 54V.

Now from what I've read, I'm basically trying to have the batteries yo-yo'ing between that fully charged capacity and some cut-off where it stops using them and starts charging them. Below that cut-off is the *actual* cut-off where it cuts power to the house because the batteries are depleted. In other words, let's say the batteries are considered depleted at 50%, and fully charged at 100%. If I set my cut-off to 70%, then they will be drained from 100% to 70%, and then the inverter switches to mains. The batteries are then charged (either from solar or from mains, whichever is available) back up to 100%, and then drained down to 70% again. In the event of a power outage, I still have that extra capacity from 70% down to 50%. Does this all sound correct?

In that event, let's say I want to target 1200W of continuous draw over 3 hours as my reserve. I'm struggling to figure out:

1. What I should set as my output source priority (setting 01)

2. What is a safe maximum charging current (setting 02)

3. What my voltage point for setting 12 should be, "Setting voltage point back to utility source when selecting “SBU priority” or “Solar first” in program 01."

4. What my voltage point for setting 13 should be, "Setting voltage point back to battery mode when selecting “SBU priority” or “Solar first” in program 01."

5. What I should set as my charger source priority (setting 16)

6. What my low DC cut-off voltage should be (setting 29)

 

I'm happy to pay for professional advice in this, and am happy to take recommendations on that too. Thanks!

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Hi.  Welcome to the forum.

Just to check your battery set-up. Do you have 4 sets of 4 batteries?

This gives you 'n bank of 400 Ah.

Thus you should not charge your bank more than 10% of the size at a C10 rating.

As you have 2 Axperts you need to set each to 20 amps max at the amps of each inverter is added up.

Why do you want to charge your batteries with Eskom ?

The output priority depends on what you want to do. I wrote software to manage that for me as I did not want to have to worry about it,

But it all depends on what you want to do.

 

 

 

 

 

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3 minutes ago, jdp said:

Hi.  Welcome to the forum.

Just to check your battery set-up. Do you have 4 sets of 4 batteries?

This gives you 'n bank of 400 Ah.

Thus you should not charge your bank more than 10% of the size at a C10 rating.

As you have 2 Axperts you need to set each to 20 amps max at the amps of each inverter is added up.

Why do you want to charge your batteries with Eskom ?

The output priority depends on what you want to do. I wrote software to manage that for me as I did not want to have to worry about it,

But it all depends on what you want to do.

 

 

 

 

 

Thanks:)

 

Ja it's 4 batteries in series to get to the nominal 48V, and then 4 of those in parallel.

I don't want to charge them off Eskom, necessarily, but I do want them to have that buffer space so I have 3 hours of power if there's a power failure.

Is there an advantage to managing it via software than letting the onboard firmware manage that? My home automation controller (a Windows box) is monitoring both inverters using MppSolarPatrol, so I'm open to using software to control it. Can you link me to yours?

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fluffypony welcome to the forum.

Another thing you should really consider is getting yourself a Victron BMV 702 Battery monitor as the SOC on the Axperts are basically useless at begin accurate.

You will notice most of us running Axperts are doing that and that the software jdp wrote even works with the BMV to control the inverter better using accurate SOC readings.

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HI Fluffy

Welcome.

I tried to write a simple set of instructions for setting up Axperts and it is available off this forum for download. I can whole-heartedly recommend you get a BMV 702 with a midpoint probe as said here earlier the SOC for Axperts is useless. The BMV is a sizeable investment but your battery bank is even more so. I liken an Axpert like driving a car without a fuel gauge  - you going to run into trouble sooner or later. The BMV solves this

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