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Axpert VM II 5KVA Inverter [Programming]


Omarsz
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Hello everyone

I'm happy I've found this forum. I've seen plenty of people happily helping each other patiently with pretty technical stuff. 

I need some help with Programming my Axpert VM II 5KVA Inverter which was installed 2 weeks ago but I've felt the engineer wasn't used to such inverter and I'm worried the system isn't well programmed. 

I've been reading quite a lot lately, yet, I don't like to reach to conclusions or take actions without supervision or guidance from well informed and experienced engineers/technicians.

Here are some info about the system:

  • 6 * 330 Watts Suntech Panels (Connected in Series)
  • Axpert VM II 5KVA 48v Inverter Link
  • 4 * newmax SG 2000h 200Ah Batteries connected in Series. Links for Page + Link for PDF

Watchpower settings:

Questions:

  • Anything wrong with the settings? Any comment on the pictures would be highly appreciated. (Bulk Charging, Floating Charging voltage?) 
  • Battery Cut-off Voltage: 42 V (I've read that this equals to 0% battery level), if this is bad (as I've read), what Voltage equals 50%?
  • I've read that Axpert reading of battery level (based on Volts) is pretty bad. Can you give me suggestions of Battery Monitoring tool to buy? (If Victron BMV, which version?)
  • I have been using Axpert 3kva VM 24v inverter with 2 * 200AH batteries. I feel like they give the exact same perforamce like the 4 * 200Ah with the 48v VM II inverter. Is that because of the higher voltage? (When compared in terms of usage hours.)

I'd appreciate any help with this after these 2 weeks of frustration lurking the web for answers.

Thanks everyone

Edited by Omarsz
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Hi Omarsz 

Welcome to the forum I have flu so it feels like my head is going to burst =-quickly

Max charging should be at 20A for now until I ahve looked at your batteries datasheet. 60 A seems too high.

On 2018/08/17 at 9:50 PM, Omarsz said:

Battery Cut-off Voltage: 42 V (I've read that this equals to 0% battery level), if this is bad (as I've read), what Voltage equals 50%?

roughly 48V is 50%. It would seem that there are several settings that are incorrect but I would have to confirm and I am just too ill to spend time looking at datasheets. Tomorrow maybe.

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7 hours ago, Chris Hobson said:

Hi Omarsz 

Welcome to the forum I have flu so it feels like my head is going to burst =-quickly

Max charging should be at 20A for now until I ahve looked at your batteries datasheet. 60 A seems too high.

roughly 48V is 50%. It would seem that there are several settings that are incorrect but I would have to confirm and I am just too ill to spend time looking at datasheets. Tomorrow maybe.

Thank you Chris and I hope you'll recover soon.

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Morning @Omarsz

Attached is your batteries datasheet they are unusual in that they don't specify either a charging current nor an  absorb voltage.

 85.pdf

With that short coming in mind we will use standard values or existing values if they are not excessive.

Bulk charging voltage leave at 56.6V. 

Float charging 54.4 V

Battery Cut off voltage 47V

Back to grid voltage 48V

The charging regime is very high Gel and AGM batteries can accept higher charge but probably 60A is to high. Fortunately their rapid increase in internal resistance restrict current flow. I would try charging at 30A and if that is not problematic raise it to 40A and see.

Ac charging I would make also 30A.

Back to discharge voltage I would make 53 or 54V.. 

 

 

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1 hour ago, Chris Hobson said:

Bulk charging voltage leave at 56.6V. 

That feels low to me. The documentation is sparse on this info, but looking at the one link, they provide this chart:

Selection_214.png.8bac6d91c46460f0125f540e112a97a1.png

That seems to suggest an absorption voltage of around 14.6V is wanted per 12V increment, so 58.4V for absorption.

On the other hand this image seems to call for something lower... probably float voltage?

Selection_215.png.574b2ae6ab14246e8e32657130ea6700.png

At 25°C. 2.23V times 24 is around 54V, so there I agree with you.

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23 minutes ago, plonkster said:

That feels low to me. The documentation is sparse on this info, but looking at the one link, they provide this chart

My AGMs absorb was at 56.4V and the Axpert's default for AGM gels is 56.4V so  56.6V  did not look out of place but really some basic guidelines would be nice.

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Update:

I went with 58.4V. 

But an hour later, I got this error. (beeping error) 

04 (battery voltage is too low according to the inverter manual)

https://imgur.com/a/8CRJr7O

Watchpower screenshot:

https://i.imgur.com/xrgOxKP.png

Weird thing is, I have almost no load (5-10w. An internet router is connected only.) and the batteries are still charging (6:50 pm. Very low charging) and I haven't been using the battery at all yet.

Edited by Omarsz
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If you just changed all the voltages then there may be a bit of time while everything settles that the Invertor thinks everything is haywire (the batteries weren't at the voltages that you set them to - yet). Give it a few hours.

58.something is good for Lead Acid (especially those that you can add electrolyte to), and Ok for Gel and others if it's only doing it sometime (not multiple times each day) - your settings seem to indicate that. Can change that lower if needed later - Sealed or Gel Electrolyte can't be replaced so need to be slightly careful here - but it depends on useage and many more factors that are difficult to determine with anecdotal info. But if you decide to stick with 56V to be safe, then do yourself a favour and at least 1/6Months kick it up to about 59V for a while to avoid sulpheration (applies even to Gel/VRLA - they need to boil a bit to get rid of sulphur buildup - but learn about batteries in the meantime so that you understand I am not trying to steer you wrong, I don't know everything).

1. Battery Equalisers - Trust me, no matter what batteries you have, from cheap to expensive - you have to have something that keeps your batteries balanced - This can be expensive as a Full BMS, A high end Victron Balancer or just a HA02 on each bank if they are loose like yours (get a price from @Chris Hobson otherwise you might wait weeks if importing)

2. With a single bank of batteries like yours, then you will hate the price of a Victron BMV702 (battery monitoring), since it is around the price of another battery... But mid-point monitoring (checking the voltages at the half-way point of your battery bank), and the much more accurate ACTUAL usage of your batteries (terms like SOC/%DoD, Time, etc) will make a lot more sense with accurate measurement. You can do some of the same with a less powerful Victron monitor (600/700), but monitoring the Midpoint is critical in identifying a battery failure (See my lessons learned Blog), and there is even a temperature option if you need later.

3. You have started almost exactly at my original specs, and if this is a backup unit then you should be fine. Don't be in a hurry to try save Municipal power yet, the Axpert is really a high power UPS system with advance features (your installer/supplier probably didn't sell it to you like that). A hint: Even with the low switch time of the Axpert, I had issues on a few pieces of computer equipment during switchover (Note: this also might have something to do with the Earth Break between Neutral and Earth - I never solved this myself), so put a basic UPS on your Critical items that can't take the switchover (you will know which ones they are when the 40ms isn't enough and your PC or DSTV resets - 40ms is my experience, even though it's supposed to be less, there is even a setting that says so).

4. Ask an electrician to check your grounding/earth both when the Axpert is running with Municipal Power and when it is operating (isolated) in UPS mode, sometimes they need to look at a second earth bonding to Neutral after your Axpert. So far I have never seen/experience/read any danger, but I have been lightly shocked/tingled by things that I though were earthed. In SA the Earth is almost always bonded to Neutral on the Municipal side, but the double pole switch in the Axpert means it can disconnect that bond. I resolved by adding a Earth to Neutral bond (wire) in the DB board, but highly suggest you get a decent Electrician to qualify this for you properly.

5. I know this is budget dependant - but even if you only draw 500W/hr a 200Ah bank of batteries is only going to be workable (without damaging them) for a few hours and not enough normally to last a night before the sun comes up again. If you need them to last longer (especially since the Axpert misuses the Voltage setting - oddly the Axpert works in your batteries favour in this regard normally), try get a second bank of batteries as your first priority when you decide to upgrade stuff (after doing the above stuff and bearing in mind that you will also need a balancer - Item 2 above - for those as well)

Ok, after all the noise above, just enjoy your start into Solar - trust me it gets confusing, and you will occasionally think you might have wasted your time and money, but it is both fun and worth it in the end. And yes, you will find that there are a lot of things that you would have done different, but unless you start somewhere, you might not have started at all.

Regards
KLEVA

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9 hours ago, Omarsz said:

But an hour later, I got this error. (beeping error) 

04 (battery voltage is too low according to the inverter manual)

I note that the battery voltage is 49.1 V, and the battery cutoff voltage setting is 47.0 V. In the non-VM versions, the battery is considered low when it falls to less than but not equal to the battery cutoff setting plus 2.0 V. So that limit would be 49.0 V. It's not considered to have recovered from being low until the battery voltage exceeds 4.0 V more than the low voltage cutoff setting, or in your present case, 51.0 V. 49.1 V seems very low for a lead acid battery if it's being charged at all.

[ Edit: so if I got this right, when the screen shot was taken, you were just 0.2 V above the low battery situation. You'll need to charge to 51.1 V or higher to remove the warning. ]

Just to get the low battery warning out of your face for now, set the battery cutoff voltage a bit lower, say 45 V. The normal value for lead acid (if you don't use the User setting for the battery type) is 42 V, so that's not crazy low.

I've just checked the VM II firmware version 20.44 (yours is 20.45), and it appears to use the same limits.

[ Edit: "less than or equals" -> "less than but not equal to"; "reaches" -> "exceeds". ]

Edited by Coulomb
As noted
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On 2018/08/17 at 9:50 PM, Omarsz said:
  • 4 * newmax SG 2000h 200Ah Batteries connected in Series. Links for Page + Link for PDF
  • Battery Cut-off Voltage: 42 V (I've read that this equals to 0% battery level), if this is bad (as I've read), what Voltage equals 50%?
     
  • I've read that Axpert reading of battery level (based on Volts) is pretty bad. Can you give me suggestions of Battery Monitoring tool to buy? (If Victron BMV, which version?)

How long have you had these Newmax batteries?

And how frequently have they been drawn to 42v?

Which battery monitor? A Victron BMV702, like here: https://www.victronenergy.com/battery-monitors/bmv-700
Make this a priority purchase.

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I'll re-read all other posts again and I will see what I should be doing afterward.

8 hours ago, The Terrible Triplett said:

How long have you had these Newmax batteries?

And how frequently have they been drawn to 42v?

Which battery monitor? A Victron BMV702, like here: https://www.victronenergy.com/battery-monitors/bmv-700
Make this a priority purchase.

 

I've purchased the whole system on the 1st of August, 2018. Almost a month old.

I've noticed that the Battery voltage goes down pretty fast. Yet, I don't remember I've reached the 42v level at any day yet (maybe once after the first programming of the inverter but maybe because it didn't have enough time to charge the batteries.) 

What I've noticed is as soon as PV doesn't provide enough electricity, (~7:00 pm; it's 7:13 pm now.) the battery voltage goes down pretty fast (from 56.6 to 49 to 46 in no time.). It's 46.4 now and 0 watts from PV (7:14pm).

Note:

I don't use Utility to charge the batteries at all.

 

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2 minutes ago, Omarsz said:

... the battery voltage goes down pretty fast ...

Adding onto what the others are suggesting you look and and do / change, I'm just looking at more options.

Is there a way that you can load test each battery individually?

Reason being that if the charge drops fast from 100% SOC, there could be a chance that their is a battery or batteries that are faulty.

Another way to try, whilst the batteries are being charged, or under load, feel them for heat. On the sides, poles. Any heat, suggest a faulty battery.

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Will keep all these options in mind and I'll consult another engineer. 

Another note:

My average consumption on battery is around 80watts at any time. I hardly cross the 130watts and if I do, it won't last for more than few mins (less than 10 mins). 

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7 hours ago, The Terrible Triplett said:

Here is a Excel spreadsheet that you can use to calculate your loads, batteries required and panels needs.

Let us know your findings.

Master - Off-Grid - Solar Panel-Design1.1.15.xlsx

Good file! Would you upload it to the file section for us? It will be most helpful to all I'm sure.

Thanks 'the notorious' ;))

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7 hours ago, Energy said:

'the notorious' ;))

BWHAHAHAHAHAHA --- I see what you have done ... if that is not the coolest move I've seen in years, I don't know what is!!! :D

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36 minutes ago, The Terrible Triplett said:

BWHAHAHAHAHAHA --- I see what you have done ... if that is not the coolest move I've seen in years, I don't know what is!!! :D

Hey! Why do you get a third-princess ribbon!?

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8 minutes ago, plonkster said:

Hey! Why do you get a third-princess ribbon!?

Because I am "The TERRIBLE Triplet" who notoriously poke the bear with my tongue firmly in my cheek.

Like so:

 image.png.1900a9b05dee6c7054927626e16750a2.png

I think you should get a "Philosopher" ribbon. what do you think?

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17 minutes ago, The Terrible Triplett said:

I think you should get a "Philosopher" ribbon. what do you think?

I was thinking more of Blabbermouth but I'd prefer my title to be awarded :-)

(Apparently I got the reward for the guy who talks the most at my previous job, at the year-end function... AFTER I've left!)

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