I am HUMBLED by all the FANTASTIC help I receive on this forum. I so hope I meet some of you at some stage so I can buy you a beer to show my appreciation. I live in Cape Town - Devils Peak (city bowl) and would welcome if someone can show me what to do or allow me to visit them and see what they have done and hopefully build the courage to have my PC do the thinking and controlling. I can handle "spanners and steam" and installed the panels myself and it looks super on my roof but it is the "bliksem" Inverter that "check-matt" me. 

Thank you. PLEASE mail me the drawing to [email protected]

Thanking you in advance.

"Wingman".

 

Cool.

Would help most certainly as I am in Belville.

I do have a BMV but no Axpert no AICC and no Pi ... Victron, tablet and SolwEB. 

Any Axpert mense in Cpt?

3 hours ago, The Terrible Triplett said:

Any Axpert mense in Cpt?

There's a company here called SolarMD that installs them and has obtained the rights/abilities to load their own firmware. They install them with "MyPower24" Lithium Ion batteries.

How does the BMV help you without the other "fancy stuff"? May I please come and have a look at what you build? 

BMV is there to give you information on your battery, so that you can ensure they are not abused, reducing their lifetime.

They have a display built to view all the values, that has been the norm for years with no software to make it easier. All the software is new.

7 minutes ago, Wingman said:

May I please come and have a look at what you build? 

Are you referring to me, not having a Axpert?

1 minute ago, Wingman said:

How does the BMV help you without the other "fancy stuff"? May I please come and have a look at what you build? 

They use a simple method. When the SoC is high enough, the relay in the BMV opens, removes power from another relay/contactor which then disconnects the inverter from the grid, forcing it to use battery power (like a UPS). When the SoC goes low enough, the relay closes, which in turn powers up the contactor and reconnects the grid, so the inverter switches to bypass. At least, that's what I think they do.

TTT has a changeover contactor setup that disconnects the inverter, waits a second, then reconnects the grid, also based on BMV relay inputs.

I like the simplicity of these solutions, but.... you know.... that assistant stack... I would miss it so much if I didn't have it.

Plonkster, thanks for the explanation of what a BMV does, but I thought that is precisely what my expensive 5KV Inverter is suppose to do. Where am I going wrong?

5 hours ago, Wingman said:

... but I thought that is precisely what my expensive 5KV Inverter is suppose to do. Where am I going wrong?

The Axpert doesn't count coulombs (amp.seconds, 1/3600th of an Amp.hour). The BMV does. The Axpert has the hardware and the controller horsepower to do it, but for whatever reason, the manufacturer feels that voltage is a "good enough" indicator of state of charge. Despite this limitation, the Axperts are still good value for money, even when you add the cost and complexity of an external coulomb counter.

Edit: when you count coulombs (or amp.hours), you get a much better measure of the state of charge of the battery than you do by using only the battery voltage. So you are better able to prevent over-discharge of the battery, which prolongs its life.

Edited September 29, 20169 yr by Coulomb

5 hours ago, Coulomb said:

when you count coulombs (or amp.hours), you get a much better measure of the state of charge

 

Take a car battery. This is usually a smallish battery around 50Ah. When the starter motor is running, it will drop the voltage to 10V or even 9V, for a few seconds. When you take the load off, it will bounce back to 12.5V or more.

So, did the battery drop to empty (10.5V is technically empty) and recharge really quickly? Of course not!

Same with the Axpert. It will think the battery is low, while it's just working a little hard right now. Similarly, it will think it's full when it's really not.

The only way to know is to count the electrons as they walk past, and then to do a row-call tomorrow and make sure they all came back. Of course we don't do this on electron level, but we sorta know what the charge of an electron is, so we know how much joules there are, and we know a joule per second is an ampere, so Amp-hours translate directly to joules, so counting amp-hours is sorta kinda the same thing as counting electrons.

Something else that comes into this is voltage efficiency. Take the same 12V 50Ah battery and lets say it is half empty, so I need to put 25Ah in to fill it up. I will do most of the work at 14.5V (absorption voltage), so I put in 14.5*25 = 360Wh. I then discharge it back to 50% at a rate of 5A. 5A as a fraction of the overall capacity (50Ah) means it would be empty in 10 hours, so we will say that 5A is the battery's C10 discharge current (The more attentive among you will say I forgot Peukert, we'll leave him out for now). When a battery works at C10, the voltage drops a bit more than if it works at say C20 (which is a better deep-cycle rate), so lets say the battery voltage drops to 12.2V at C10. So now you get out 12.2 * 25 = 305Wh. So you put in 360Wh and you only got 305Wh back out. This is voltage inefficiency. BUT... you got the same Ah out as you put in... and that is the key. Got to leave voltage out of it, which is precisely what the Axpert doesn't do :-)

Check this out, how he only gets 50Ah out of a 100Ah battery (Peukert), but then he discovers the other 50Ah is still there...

 

Jaco de Jongh I was not trying to mislead Wingman or anyone else but you will notice that Wingman on the previous page said that his aim was to use solar when available and make sure that his batteries were fully charged in the event of an emergency. If setting 12 on the Axpert was set to its highest value of 51V or 12.75V per battery for his 12V batteries, he would pretty much achieve that. Also I am no expert regarding the BMV but won't it be an unnecessary expense using it to drive AICC with an Axpert inverter, if your aim is to use the inverter purely for solar power with batteries used only in the event of grid failure. Perhaps you could publish your wiring diagram in this discussion for all to benefit.

As I said I was not trying to mislead anyone but am quite glad I said what I did as it gave rise to lively and most informative replies from which I am sure many others could learn plenty. I have to say I certainly did.

23 hours ago, Jaco de Jongh said:

I feel that statement of yours might mislead inexperienced guys

Hi Ebrsa, I never thought that you will intentionally mislead the guys, I just needed to clarify that the BMV can still be of great use without the AICC part. 

1 hour ago, ebrsa said:

but won't it be an unnecessary expense using it to drive AICC with an Axpert inverter

Not at all, the Axpert looks at volts, and the BMV looks at the true State Of Charge or Dept of Discharge. It is constantly looking at what current goes into and out of the battery bank, adding and subtracting the readings to give you a true reflection of your batteries strength at that time. @Coulomb and @plonkster gave great explanations about it in this thread.

With the Axperts and Infini's, they only look at volts. If you for example draw a 2kw load from the inverter, running on batteries only,  you might get a reading of 48.5volts, if you then switch off some of the load and use only 200watt, you will see that the battery volt reading increases without being charged. (hope this makes sense). So to use the inverter to protect the batteries using the Volt reading only, will not be accurate at all. @Chris Hobson and @plonksteralso talks about this a bit earlier in this thread.

In my opinion, the cost of the  BMV will never be unnecessary. It is the best investment you can make towards protecting your batteries.

It is so accurate and trusted that all the software developers uses the BMV's readings in their software.

I will use some drawing software to draw the circuit I am using, dont think anybody on the forum will be able to, or even want to try and read my hand writing. Will try to do it this weekend.

Where do I buy a BMV and what make should I search for or are all models of BMVs the same? I live in the city bowl in Cape Town. I understand there is a "shop" in Somerset West or is there a place closer to home I can buy one?

Check your inbox bud

Since this topic has addressed a number of issues relating to the Axpert with valuable information being provided, perhaps I could continue with another matter of concern. My AICC is set to switch to solar at 98% SOC and back to grid at 80%. On grid with zero solar it continues to draw about 1.2A from the batteries. My concern is that when on solar during the day with the batteries above 98% SOC, I have seen current drains as high as 73A when my wife is doing her magic in the kitchen. I have 2 x 5Kva Axperts in parallel with a 48V 225AH battery bank (Trojan T105). The only solution other than manually switching to grid at times of high battery drain, if I even notice it, that I can think of is to double the AH of the batteries. I have suggested to TinkerBoy and Manie that an AICC feature to switch to grid when the load is higher than a programmable value and back to solar when it falls to a lower programmable value, would be a desirable feature and am holding thumbs. I am using a BMV700 to control AICC. Can some kind person think of another solution as I really would not like to spend more money on batteries as at my age of 78 the batteries will probably outlive me if I treat them with care. My objective is to use the 2250 Watt panel capacity, which is all I have space for on the roof, as effectively as possible with minimal battery feed. However when the batteries are nearly at 98% by around 10:30am, the solar feed is not optimized as I charge from solar only. The charge current is then fairly low. If I manually switch AICC to Battery, the solar watts increase substantially to supply the load and continue charging the batteries.

AICC download : For unknown reason AICC cannot be dowloaded from aicc.org.za. When clicking on the icon for download nothing hapens. Also confusing is the text below the icon: We will release AICC Pi V 1 soon.  

Is there another source where one can download that software?

AICC pi is for the radpberry pi. We busy with final bata test before we release it

Sent from my SM-G920F using Tapatalk

@Chris Hobson can you help @Wingman on setting up his Inverter?

Wingman, Chris is very jacked on setting up the inverters. Rest will jump in.

Once you have the rest in place, I can sort the BMV for you remotely.

Hi TTT

Happy New Year! I think Wingman is flying so to speak. The thread has been quiet for a while. Did give him some pointers a couple of months ago.

 

Same to you Chris. 

Wingman is trying his best to get here again. I just cannot help him on the Axpert so I said this is the best place for settings bringing him back here.

OK I'll try and help.

 

AICC download : For unknown reason AICC cannot be dowloaded from aicc.org.za. When clicking on the icon for download nothing hapens. Also confusing is the text below the icon: We will release AICC Pi V 1 soon.  
Is there another source where one can download that software?

Ther is no more AICC for the pi. Only for windows.



Sent from my SM-G920F using Tapatalk

I am in a similar boat to where wingman was. when it come to the setting on the axpert im LOST! I hope he doesn't mind me adding my question here. I have the RCT 5kva inverter with 8X105ah Royal Lead Calcium batteries. No solar and just using as a back up for now. Having read, i have made some of the changes suggested but also left as default where not sure. Below are my setting. Anything i need to change?

 

1 – UEI

2 – 60A

3 – APL

4 – SdS

5 – FLD

6 - LⱵd

7 - EFD

9 – 50Hz

11 – 20A

12 – 46V

13 – 54V

16 – SNU

18 – b0N 

19 -ESP

20 – LON

22 – AON

23 – bYd

25 – fds

26 – 58.4V

27 – 54V

28 –PAL

30- ONE

31 – SBE

7 hours ago, Richyv said:

I am in a similar boat to where wingman was. when it come to the setting on the axpert im LOST! I hope he doesn't mind me adding my question here. I have the RCT 5kva inverter with 8X105ah Royal Lead Calcium batteries. No solar and just using as a back up for now. Having read, i have made some of the changes suggested but also left as default where not sure. Below are my setting. Anything i need to change?

 

2 – 60A

11 – 20A

12 – 46V

13 – 54V

26 – 58.4V

27 – 54V

 

Hi 

Most of your settings are fine.

I would reduce program 2 to 20 A in anticipation of you going over to solar

Program 11 is good.

Program 12 raise to 47 or 48 depending on load.

Program 13 raise to 55 or 56V also in anticipation of you going to solar.

Program 29 should remain on the default 42 V.

I'll give a full explanation when I don't have to deal with a touch screen.