Program settings Mecer 5kVA inverter/charger

[Bushtracker]

Hello everyone, I am a newboy to this discussion and world of renewable energy. I have recently had installed a Mecer Axpert 5kVA inverter/charger, model SOL-I-AX-5P, with 4 x 200  AGM Vision batteries, which started off as simple backup, but quickly grew to a ‘semi-off grid’ system when we added an array of 6 x 340 Watt PV panels.

I was led to believe this inverter was a true hybrid however soon found out that instead of sharing the loads it switched from battery mode to utility (line mode) when the set criteria were encountered.

I am very afraid with this sort scenario, that I maybe abusing my batteries and am relying totally on the charge controller to regulate the batteries in the best way.

The Watch Power software ver 1.13 is running nicely where I can monitor the ‘invisible’, and I have changed the following settings from the default factory settings on advice from a colleague.

·        Setting 01: SbU – ‘Solar first’

·        Setting 12: 48 v – Voltage point back to utility

·        Setting 13: 54 v – Voltage point back to battery mode

·        Setting 16: OSO – Only solar energy to charge the batteries

 

The rest of the settings are on default.

I would be most grateful for comments and advice from those who have experience with this inverter, especially on the settings and whether there are other settings that require adjustment?

I acknowledge that my array of panels maybe a little under-powered but am retired and happy to manipulate the use of the heavy-use appliances, and accept that on an overcast day we will be paying the utility mainly.

 

[Coulomb]

On 2019/10/20 at 4:29 PM, Bushtracker said:

I was led to believe this inverter was a true hybrid however soon found out that instead of sharing the loads it switched from battery mode to utility (line mode) when the set criteria were encountered.

That's right. But if you have enough panels (you don't at this point), you can stay in battery mode almost all the time, and then you will be blending solar and battery power to supply the loads, with any excess solar energy charging the battery.

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I am very afraid with this sort scenario, that I maybe abusing my batteries and am relying totally on the charge controller to regulate the batteries in the best way.

Well, that's always the case. There are bugs in the factory firmware that will under-charge your battery, so consider patched firmware. Your is probably one that can use the updated, patched firmware.

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·        Setting 01: SbU – ‘Solar first’

[ Edit: I read "solar first" and didn't look at the lettering; Solar first is actually called SUb on some inverters, and SOL on others. So I'm still not sure what setting you were using. ]

This means that you will go to utility mode at sundown. That might be what you want, but usually you'd want to use your stored solar energy for as long as is safe, which would be SbU output source priority.

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·        Setting 12: 48 v – Voltage point back to utility

Perhaps consider raising this to 49 V or even 50 V, so that you battery doesn't discharge so far.

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·        Setting 13: 54 v – Voltage point back to battery mode

·        Setting 16: OSO – Only solar energy to charge the batteries

Those are good.

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whether there are other settings that require adjustment?

Make sure that setting 02 (maximum charge current) is set to what you battery manufacturer recommends.

Also consider setting 05, perhaps set to USR (then you have to check that 26 and 27 are suitable, but the defaults are for AGM), so that you can set the DC low cut-off voltage (setting 29) to something higher than 42 V. Don't make it higher than 2.0 V less than setting 12, however (see FAQ Q2).

Edited October 23, 2019 by Coulomb

[Dex_]

2 hours ago, Coulomb said:

This means that you will go to utility mode at sundown. That might be what you want, but usually you'd want to use your stored solar energy for as long as is safe, which would be SbU output source priority.

I think you mean it will go to battery at sundown, and that he wants to possibly use SUB not SBU?

Edited October 20, 2019 by Dex_

[Coulomb]

12 hours ago, Dex_ said:

I think you mean it will go to battery at sundown,

No. SOL output source priority mode is about keeping the battery full. Good if you want to last the longest during blackouts, but bad if you want to minimise utility costs.

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and that he wants to possibly use SUB not SBU?

No. Assuming that you want to minimise utility usage, you want to prioritise battery over utility. So the B has to come before the U. 

[Bushtracker]

Thank you Coulomb and Dex, for your comments and advice, they are much appreciated! I do believe I have a genuine machine (see image below)  so will consider the firmware update, but notice the adage "Not for the faint hearted" Hmmm!

As soon as I have the details of the batteries I will adjust settings 26,27,29 accordingly.

The discussion on setting 01 - Output source priority:-     We are trying to minimise utility costs, so  I have set this to SBU so that at sunset, so the inverter switches to battery mode for as long as its safe. the 'point back to utility' , setting 12 , will be adjusted once I get the properties of the batteries.

 

[Bushtracker]

On further inspection I have concluded that I am running a 5 kW model, (see image below) with the usual 58.4 V battery voltage limit (no 64 V option). So believe there are no patched or downloadable factory firmware for this inverter!? So we will have to live with it!

This brings me to a further question regarding setting 13.  If 54v is the battery voltage limit for my model is 'Battery fully charged' the same thing?

 

[Coulomb]

20 hours ago, Bushtracker said:

The discussion on setting 01 - Output source priority:-     We are trying to minimise utility costs, so  I have set this to SBU so that at sunset, so the inverter switches to battery mode for as long as its safe.

I'm still confused as to what you had, because you called it SBU and "solar first", when these are not the same thing. So you had SBU all along?

[Coulomb]

20 hours ago, Bushtracker said:

On further inspection I have concluded that I am running a 5 kW model, (see image below) with the usual 58.4 V battery voltage limit (no 64 V option). So believe there are no patched or downloadable factory firmware for this inverter!? So we will have to live with it!

Actually, Weber and I have finally acquired firmware version 74.40, and we have promised to patch any Axpert 48 V 5 kVA firmware that is for a machine with a 145 V max SCC. The only thing is we didn't say how soon  I'm busy with other things at present. So you won't have to live with it forever.

20 hours ago, Bushtracker said:

This brings me to a further question regarding setting 13.  If 54v is the battery voltage limit for my model is 'Battery fully charged' the same thing?

Not quite. The FUL setting means that the charger has transitioned from the absorb stage to the float stage. So that's the end of the absorb stage. Just hitting the absorb voltage happens at the start of the absorb stage. So the two could be different by 10-60 minutes depending on your battery details, solar availability, and so on.

[Bushtracker]

On 2019/10/23 at 6:16 AM, Coulomb said:

I'm still confused as to what you had, because you called it SBU and "solar first", when these are not the same thing. So you had SBU all along?

Thank you Coulomb, sorry for the confusion, my mistake. Setting 01 has 3 options for output source priority .viz: Solar first 01 SOL, Utility first 01 UE1, and SBU priority 01 SBU. Where the confusion is ,is that with both 01 SOL and 01 SBU , I understand that Solar energy provides power to the loads as "first priority"  which I read as 'Solar first' .  So yes I have set 01 to SBU .

With regards  setting 12 - voltage point back to utility - set at 48v at the moment - my over-night storage is sufficient to take care of the basic demands and draws the batteries down to between 48.3 and 48.5 . If I raise the voltage to 49v it will definitely switch to Utility, probably in the early hours!? I will make the decision as to whether I accept the cost of a short spell of utility for the sake of the health of the batteries, or leave as is.

Can you tell me please the relationship between battery capacity and battery voltage  - for example I will see battery capacity 63% and battery voltage display at that time as being 48.5 v  ? Are they equally as important to as an indication of the state of the battery?

Thank you for your help

 

 

 

[Coulomb]

3 hours ago, Bushtracker said:

Can you tell me please the relationship between battery capacity and battery voltage  - for example I will see battery capacity 63% and battery voltage display at that time as being 48.5 v  ? Are they equally as important to as an indication of the state of the battery?

They're equally "important" because they're essentially the same thing. The code is confusing, but it looks like most of the time, the SOC is calculated as

SOC (%) = ((Battery voltage) — (Setting 29) — 0.2) * 10   (Setting 29 is low DC cut-off voltage)

In other words, you get 1% of SOC for every tenth of a volt that the battery voltage exceeds (setting 29 + 0.2 V).

If you low DC cutoff voltage is 42.0, then for a battery voltage of 48.5 V we have

SOC = (48.5 - 42 - 0.2) * 10 = 63%

This formula works up to 95% SOC; more than 95% SOC isn't allowed unless other criteria are met.

In other words, the SOC figure tells you nothing more than the battery voltage with a scale and offset. This is a very crude approximation. If you have a BMV or similar battery monitor installed, it can count coulombs (Amp·seconds) of charge into/out of the battery, adjust for the Peukert coefficient, and ignore the battery voltage which depends on temperature, load, and internal resistance. This will give a much better estimate of the battery state of charge.

[Bushtracker]

Hi Coulomb, thank you for your detailed explanation of the state of charge calculation, glad WatchPower does it all for me!

At the risk  boring you with trivial questions, I do have a query about switching from line mode to battery mode. I have noticed that during daytime, having dawned in line mode, when PV power is adequate to take care of the load and charge the batteries, once 100% is achieved the system does not switch back to battery mode for 25-30 mins. Is that normal?? I have not changed any settings from my first post yet.

Thank you so much in advance, I hope to be running on my own very soon!

 

[Coulomb]

18 hours ago, Bushtracker said:

I have noticed that during daytime, having dawned in line mode, when PV power is adequate to take care of the load and charge the batteries, once 100% is achieved the system does not switch back to battery mode for 25-30 mins. Is that normal??

I have never used lead acid batteries on an Axpert, so this is outside my area of expertise. I would think you would want to go to battery mode soon after dawn, so I suggest that you start reducing setting 13 until you get closer to that situation. Perhaps start with 52 V (13.0 V per nominally 12 V module). Even if you are charging at a high rate, that should still be a fairly full battery, well able to cope with a few clouds if necessary.

[Truts]

I've got a 5kv mercer inverter charger and want the SBU to run in the day and Sub to run at night for now .  currently it's running SBU right through the day. I don't want utility to run in the day

[ebrsa]

@Coulomb  It would seem from your posting above that your and @weber 's proposed future version 74.4 firmware will also be suitable for my Axpert 5KVa 4Kw models with 145V maximum solar input. A I right in assuming that? @Bushtracker  and @Truts  I would recommend that you have  look at ICC-Pi and a Raspberry Pi to optimise solar power with your.inverters. My house runs off a 2 Axpert cluster but the geyser is heated by evacuated tubes and for the past year grid power used by the geyser is only 120 KWh. A friend with a setup similar to @Bushtracker 's uses solar/battery power from 6h00 until 17h00. On cloudy days ICC is set to set to switch to grid when battery SOC drops to 77% and back to solar at 82% SOC. You also require a Victron BMV700 for  a single bank of batteries or BMV702 for a double Bank in parallel. Such a control setup is just infinity more flexible and accurate then Watchpower. However one does have to schedule large power consuming appliances to grid times to maximise battery life. I have 450AH flooded lead acid battery capacity and run on solar/battery from 23h00 until 17h00 the next day at present with sunny weather mostly on the West Coast. What I particularly like is that I can monitor ICC from my mobile phone with the free RealVNC viewer and make adjustments to the Axpert's settings. 

 

 

 

 

 

[Coulomb]

4 hours ago, ebrsa said:

It would seem from your posting above that your and @weber 's proposed future version 74.4 firmware will also be suitable for my Axpert 5KVa 4Kw models with 145V maximum solar input. A I right in assuming that?

That's a big question. It works; I'm running it right now. But it turns the 4 kW inverter into one that thinks it's a 5 kW inverter. The IGBTs in the inverter-proper can handle it; they were always rated for 5 kVA, so 5 kW at unity power factor is no more work for them. But the two ends of the battery to bus DC-DC converter (16 MOSFETs at one end, and 4 IGBTs at the other end) were only designed for 4 kW of real load. I don't believe that they have 25% spare capacity; they must have done something different in the PF1.0 models. The fan will run more slowly with 74.40 and patched versions thereof; for example, a 4 kW load which with original firmware commands 100% fan speed would get only 80% fan speed with 74.40.

So I think that the best thing is to use 73.00e for 5 kVA/4 kW models, unless you need to parallel them with one or more PF1.0 machines. With paralleled machines, there is less likelihood of the 4 kW machine getting overloaded. I'll be going back to 73.00e after I've done a little more testing of 74.40e, unless someone proves that our machines really can handle 5 kW continuously.

But if you want to try it against my recommendation, we made a beta release of 74.40e recently; see this post.

[ebrsa]

@Coulomb Thanks a great deal for your interesting explanation. I don't have your knowledge and skills to repair my Axperts should I blow up something. So I guess I will just continue using 73.00e as everything works just great. Thank you nonetheless for taking the time to explain it all. 

 

[Frikk3d3l]

Hi coulom. I have read through the posts and I need a different setup than #bushwacker. I have a 1kw solar setup with a axpert 5kva inverter and 4x 100ah gel batteries. My needs are probably SUB as in setting 01 but my inverter doesn't have the option. I want to power loads as cheap as possible during the day and savey battery for loadshedding. As with winter rain the sun is insufficient and then it drains the bat's and then power is off when loadshedding hits. I have set my  charging to both solar and utility but doesn't seem to do that. Stays on solar charging. Do you know what setting might work. Looks like you are the expert. 

 

[Coulomb]

6 hours ago, Frikk3d3l said:

My needs are probably SUB as in setting 01 but my inverter doesn't have the option.

What options do you have for setting 01? You didn't say what model inverter you have.

I think you're trying to achieve the impossible. Your battery is too small for your 5 kVA inverter, and your solar panels are too small to support your loads during the day. Yet you want your battery to be full for load shedding.

In this forum, we obey the law of conservation of energy

I think that the best you will be able to do is the equivalent of the SOL option for setting 01, so you'll power loads from utility at night. You will need to put settings 12 and 13 fairly high, so that it will switch to utility power during the day as well, when your battery is getting a little bit low.

[Frikk3d3l]

Hi. I am not really using the inverter ful right now. I only power lights and TV now so mostly arou d 150w to 400w at most on screen. It started out as a loadshedding backup at first bit thought I have the rest might as well get the panels to see if I can power the loads during the day. I was hoping to have this work. The solar goes to 50w from around 4 o clock then the batteries start draining to fill the loads. That is on good sun days. Friday batteries were dead because of 2 days of no sun when load shedding hit I was out of battery. 

[Coulomb]

9 hours ago, Frikk3d3l said:

Friday batteries were dead because of 2 days of no sun when load shedding hit I was out of battery

Keeping settings 12 and 13 high (say 52 and 55 V respectively) should keep the battery fairly full, assuming that you get some utility power during the day. But you'll get most or all of your loads supplied by solar power for most of the day, assuming that you get at least moderate sun.

[George Basson]

Good day to everybody,

I have 2  x 5 Kva mecer inverters in parallel. During the week we had a power failure in our neighborhood and inverters went down because of low battery charge.

I was not home at the time. I telephonically guided my wife to restart the inverters. I realized yesterday that no settings on either of the inverters display panels is possible.

Both inverters are running and it seems that settings are correct.

What can be wrong with the controls?                    

 

 

 

 

[Coulomb]

18 minutes ago, George Basson said:

I realized yesterday that no settings on either of the inverters display panels is possible.

Do you mean that pressing the enter / ⏎ button for more than 3 seconds does nothing?

Perhaps that button is dirty / worn out? Strange that it would affect both inverters, though.

[Bushtracker]

On 2020/07/12 at 4:34 PM, Coulomb said:

I think that the best you will be able to do is the equivalent of the SOL option for setting 01, so you'll power loads from utility at night. You will need to put settings 12 and 13 fairly high, so that it will switch to utility power during the day as well, when your battery is getting a little bit low.

Hi Coulomb, yeah SOL setting for 01 is what I have found best for my system. It switches over to utility at dusk and keeps the batteries charged at night in case there is load shedding to deal with. At dawn it switches back to Solar and during the day of course the solar power takes care of the loads and charges the batteries at the same time. I do however have a lot of solar power available even for dull days!

[George Basson]

23 hours ago, Coulomb said:

Do you mean that pressing the enter / ⏎ button for more than 3 seconds does nothing?

The display does change  when pressing the enter button. Then I can select a program number with the up and down buttons. Press enter again on the required no, eg  26. When I want to change the flashing figure from  56 to 54  with the up or down buttons, nothing happens. 

This is on both inverters.

[Coulomb]

47 minutes ago, George Basson said:

When I want to change the flashing figure from  56 to 54  with the up or down buttons, nothing happens. 

Is setting 05 (battery type) set to USE? Otherwise, you can't change some settings, such as setting 26 (Absorb/Bulk/CV battery voltage).