Jump to content

2 Axpert 5kva MKS in parallel - Feedback to date?


Wetkit
 Share

Recommended Posts

Hi,

 

With the current inverter pricing going through the roof, I was contemplating on perhaps running two 5kva Axperts in parallel.

To the guys out there running this way, what is the general feeling, worth it or not?

Anything to look out for?

How is the batteries doing?

Any issues?

Problems?

 

Thanks

Link to comment
Share on other sites

Hi

 

I'm running 2 5Kva's in parallel - no issues so far, but it's not even a week yet :rolleyes:

 

I do have an issue wiht the charging of the batteries which I'm trying to figure out.

My battery setting was AGN at first, but this setting does not allow you to customize your DoD.

 

When it was set to AGN, it would take the battery V (on the system at least) to 52V.

 

Now that I changed to USR the system does not fully charge the batteries even though the load is very low and there is enough PV avail to charge the batteries - stops @ 48V and the system show batteries SOC as 60% odd :unsure:

 

So I changed it back to AGN this morning to see if it will at least fully charge the batteries.

Link to comment
Share on other sites

My gut feeling is still that the Axpert is value for money, but only because it costs so little money :-) From what I heard the internal components are good quality and it will probably last for many years, but on at least some models I have some concerns with battery charging, and I expect that if you use an Axpert as anything other than a UPS (where there is ample time to float-charge it to 100%) and where you don't have some kind of battery monitor (such as a Victron BMV in place), that an Axpert is going to be harder on batteries than... say, a Victron Multiplus/Quatro with that exquisitely crafted 4-stage charger they use. Disclaimer: This is just what I hear, I have no direct experience with these inverters.

Link to comment
Share on other sites

Hi

 

I'm running 2 5Kva's in parallel - no issues so far, but it's not even a week yet :rolleyes:

 

I do have an issue wiht the charging of the batteries which I'm trying to figure out.

My battery setting was AGN at first, but this setting does not allow you to customize your DoD.

 

When it was set to AGN, it would take the battery V (on the system at least) to 52V.

 

Now that I changed to USR the system does not fully charge the batteries even though the load is very low and there is enough PV avail to charge the batteries - stops @ 48V and the system show batteries SOC as 60% odd :unsure:

 

So I changed it back to AGN this morning to see if it will at least fully charge the batteries.

 

Hi Henkt, welcome to the forum. If you set the inverter to USR, you have to configure all the battery-related settings yourself - you'll have to get the datasheet for your specific batteries and change all the battery-related settings according to that. The 60% SOC thing was explained in various threads already and it basically comes down to the fact that these inverters don't give you an accurate SOC indication and you simply have to add a proper battery monitor e.g. a Victron BM to get a more accurate SOC. The 60% SOC reported by these inverters are actually still 100% or almost 100% charged (>= 2.10V / cell).

 

These inverters only measure and compare voltages when indicating SOC and for Low-V cut-off etc. and that is actually worthless, since the battery voltage will drop depending on the load at the given time - when the load is reduced the voltage will rise again and therefor the Low-V cut-off should not be set too high to avoid unnecessary inverter shut-offs. On a 48V system, you should set the Low-V cut-off to 44V or even 42V to allow for heavy loads.

Link to comment
Share on other sites

Ok, so battery SOC is not accurate.

Anybody had issues with the PV part?

What if each inverter have a different sized PV? Will both still combine at max of each inverter, or will the lowest one be used?

Say you get 1kw and 2 kw from each PV respectively.

Will you be able to draw 3kw or will 2kw be it?

 

Software?

I have my Infini permanently connected to my PC so recording 24/7.

Will this be a problem for the Axpert?

Link to comment
Share on other sites

Hi Wetkit

 

The software is not in itself problematic. It works (sort of) however it does not give any real data. Jaco's nearly completed rendition looks like the real McCoy.

 

The newer 4048s do not have a heatsink on top. The heat sink seems to be an overkill (my one never gets above about 30oC) but this does not seem to be the only change as there have been two failures of this new model in Romania under a 500W load or less. The installer has installed dozens of Axperts and was asking whether anyone else had had failures.  MPPSolar seems to be producing them faster than they can test the new variants.

 

Whether they can balance load to PV input would be a logical implementation but software wise the Axpert is weak so they may not have implemented it. Jaco and others could answer that.  

Link to comment
Share on other sites

Thanks superdiy

 

I have two banks of these batteries and they are connected to both inverters.

 

I've adjusted my settings according to your calculations - thanks a mil :)

 

The 360Ah bank should not be charged at more than 10% (maximum 13%) of the Ah rating => 36 A (max 47A)

 

I'm not sure how the parallel Axperts handle the charging aspect, maybe someone else can shed some light on that. I assume the primary inverter (only) will handle the charging. You'll have to adjust the maximum charging current (setting 2) to 40A, if you have the option, because if I understand the manual correctly it seems that the lowest possible option for this setting for the 5KVA Axpert is 70A?  If 70A is the lowest possible option, then use that. Change the Maximum utility charging current (setting 11) also to 40A. If both (all) the inverters simultaneously charge the batteries you'll have to set setting 2 and setting 11 to 20A (per inverter).

Link to comment
Share on other sites

Hi.

 

If you run more than one Axpert then the the bank is charged by the sum of the max charging current of all the inverters together. Thus if you have 2 inverters and have a 400ah bank you set each inverter to 20amps. If you have 3 inverters and have a 500ah bank you can set 2 of them to 20 amps and 1 to 10.

 

Thanks for clearing that up.   :)

Link to comment
Share on other sites

Thanks all for the replies and the assistance.

 

If I change a setting on the master, it changes on the slave as well?

 

Thanks jpd - will it still do that if the connect PV total is not the same on both inverters?

 

In my case I have 2745W on one and 915W on the other.

 

How much power does the inverters consume by themselves?

My system goes to utility bypass sometime during the night so the efergy then reports consumption between 1000 and 2300W.

This morning I disconnected the load and the the efergy still reported 1000W.

When i reconnected the load, Watchpower reported 326W to the load but efergy still reported around 1000W

 

Is this right?

While the load was disconnected, I switched off the inverters one at a time and the consumtion remained the same, no matter which inverter was supplying power to the(disconnected) load.

Link to comment
Share on other sites

Henkt

 

I have Efergy monitors on both the feed and output of my Axpert and they don't show high internal consumption. In fact, I also have an Exsolar meter which compensates for power factor and even that shows in line with the Efergy and expected load.

So I suspect there must be something wrong with the Efergy measurement.

 

Regards

C

Link to comment
Share on other sites

Guys, regarding the Efergy monitor, it only measures the Amps and the volts is a fixed setting, so it assumes the power factor is 1.

I have seen it with mine where the current draw is 2,5amps, but the power factor is actually like 0.1

So while Efergy says 575w the real power is just about 50w.

Link to comment
Share on other sites

Guys, regarding the Efergy monitor, it only measures the Amps and the volts is a fixed setting, so it assumes the power factor is 1.

I have seen it with mine where the current draw is 2,5amps, but the power factor is actually like 0.1

So while Efergy says 575w the real power is just about 50w.

 

Same here. I have LED downlights with a power factor of 0.2.

 

I really should get of my lazy bum and build the amateur LDR+Arduino counter and stick it to the flashing LED on the prepaid meter :-)

Link to comment
Share on other sites

  • 2 months later...

Ok, time to revive this one, yet again.

 

Lets say I do run the two 5kva units in parallel, can I still have 2 seperate battery banks?

Reason for this is I can get a 2nd battery bank to what I currently have, but the battries is not the same.

I know I am going to struggle with my current bank, as it is too small.

Link to comment
Share on other sites

Ok, time to revive this one, yet again.

 

Lets say I do run the two 5kva units in parallel, can I still have 2 seperate battery banks?

 

 

I don't see why not. The two banks need not even be of the same chemistry. If the two banks are very disproportionate then you may find one inverter not quite in sync with the other in terms of charging or back to grid voltages having run the one bank down faster than the other. I know Jaco (I think) was having hassles with two inverters not sharing the load evenly. If I remember correctly it was just a software setting. Perhaps you could use that flaw to your advantage.

Link to comment
Share on other sites

No. You can not.

The inverters both check the battery volts, if they get different readings you get an error and it will shutdown. You have to use the same cable lengths also so you get the same volt reading on both inverters.

 

If that is the case I would try and see if you can split your loads and run the two inverters separately. Once you need to replace you batteries buy enough for a single bank and then parallel the two inverters.

Link to comment
Share on other sites

Would it not be idea for 2nd hand equipment for those times you get yourself into a corner, that a new person starting out can buy (with all the expertise the equipment taught the seller) at a reduce price knowing EXACTLY the limitations, so that the seller can start and a new oepsie - for resale later?  :D

 

Okay, most people say oh no, I want new, get what I pay for ... but really, sometimes you don't.

 

I for one am all for buying 2nd hand especially if the seller can tell me exactly what I am in for, what my limitations are for even with new stuff you sometimes do not get what you want, or thought you wanted till you implement it / use it over a period of time.

 

And new ones starting out, get 2nd hand batteries! Much cheaper ito school fees.

 

So anyone wanting to buy Wetkits batts?  :D

Link to comment
Share on other sites

Naw, I'm not looking to sell my exiting bank.

However, I do have 8 x 6V T105 Trojans.

The units I have see is 4 x 12V J185-HC Trojans.

If I look at the specs, the 185 units looks like 2 x T105's combined in a single unit.

 

Thanks for the link Coulomb.

Link to comment
Share on other sites

  • 2 weeks later...

HI Forum

This is my first post on this forum- I usually use wind Forum in the states- but you guys in SA seem to be installing alot of Voltronic/MPP Axpert type inverters. We've recently been installing these hybrid inverters (same manufacturer with different sticker) here in Spain.

Surprisingly the amazing technical service here is not able to tell me on how the inverters work in parallel :wacko:
 

My question is for 2xAxpert 5kVA in parallel, when programming parameters 02 and 11:

A)) Do you control the Maximum charge current (02) and Maximum utility charge (11) from just the Master?

Or

B)) Do you control them by programming the Master and the Slave and you take the resulting sum from both inverters?
 

I think this has been mentioned in this thread, but I want to make 100% sure that I understand correctly

Any help greatly appreciated

Larry

Link to comment
Share on other sites

Uhm, there is a wee bit more to it than that. 

5% for a slow charge, if you are not pushing the bank or have a lot of cycling, can charge the bank full per sun hours in a day, no reserves needed for cloudy days.

10% is normal run of the mill rule of thumb charge rate yes.

Ideal is 13%, because you work the batteries, with every 28 days equalization done on average due to being off-grid needing the power, never having a chance to properly float the bank in a day with 2 days backup - as per off-gridders up there in Alaska and other off-grid community advises.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...