Jump to content

Axpert MKS 3000 24V Overload Bypass Enabled/Disabled


AJM

Recommended Posts

3 minutes ago, The Terrible Triplett said:

Or Plonkster can modify the new Pi software to do that?

As  matter of fact, if I was interested, I could have it done using SolWEB, reading the BMV values to set the inverter to go back to grid.

facepalm

Link to comment
Share on other sites

8 minutes ago, plonkster said:

I'm pretty sure if you ask them for it, it will just show up one day three months later :-)

I forgot about that option!

Link to comment
Share on other sites

8 minutes ago, plonkster said:

I'm pretty sure if you ask them for it, it will just show up one day three months later :-)

It would be handy since you for example set it to allow for your base load and anything higher than that drain for x time means batts are doing more work than they should (or PV not up to it)

Link to comment
Share on other sites

17 minutes ago, The Terrible Triplett said:

modify the new Pi software to do that

The point is to do it without the extra stuff. The two angles I checked was 1) Can I use the relay assistant in VEConfigure to do it, and 2) Can I configure the BMV to close its relay contacts on high discharges, so then you wire the BMV relay to an input on the Multiplus and voila: High-current protection. Sadly both products seems highly fixated on voltage... which admittedly is what most people care about. At the same time, without the extra interconnecting equipment or moving the decision-making into an external system (aka CCGX), the Multiplus has no idea what the MPPTs are doing, so it simply doesn't know what the draw on the batteries are. The draw on the batteries, as far as it is concerned, is the AC-watts plus the bit lost in conversion... :-)

Link to comment
Share on other sites

This sounds like a good solution to protect batteries. I have noticed loads of 73A which won't do my 225AH batteries any good. It would be nice if the time for high load limit and the high limit can be set as well as the number of times it is allowed to switch. I would rather pay for using a bit more grid power than damage the batteries. Does anyone know what the rule of thumb for maximum recommended sustained.battery drain current is?

Link to comment
Share on other sites

1 hour ago, ebrsa said:

the rule of thumb for maximum recommended sustained.battery drain

C-ratings I think. Rates above C5 are bad news. So 225Ah, 225/5 = 45A. That's sustained of course. No problem with short bursts as high as C1, in fact the UPS bank at work would run out in 45 minutes if we actually tried to run the whole office on it :-)

Link to comment
Share on other sites

Thanks a lot plonkster. At least I have a guideline that gives me peace of mind. I have the Axpert set to maximum charge current of 20A and only charge from solar. From info on the Trojan website one should equalize the batteries occasionally with a voltage of 64.8V for the 48V bank. Looks like a separate charger is needed as the maximum charging voltage of the Axpert is 58.4V while the bulk charge voltage for Trojan T105 is 59.3V. One wonders if manufacturers even look at battery specifications to ensure that their equipment has the right capabilities.

Link to comment
Share on other sites

A question on switching under high loads, irrespective of make of inverter / MPPT, for I am thinking of charge controllers not being supposed to be switched off sommer net when they are under load.

Does it not put the components under strain that may weaken them over time resulting in earlier replacement?

Link to comment
Share on other sites

Don't know about these other makes but the Victron inverters will switch under load. Quick fail-back to grid (less than one second) is a feature of these inverters, they build them that way so you can size the inverter smaller than your largest loads :-) To make it work, the transfer switch is always sized way larger than inverter capability.

Does it put them under more strain? Of course. But I'm not going to worry about it if it was designed to deal with that strain :-)

Link to comment
Share on other sites

2 hours ago, TinkerBoy said:

One thing also to remember is that even if the software picks up there is an overload on the bank and it sends the command to switch to grid, the inverters will only switch when it is ready to do so. And that is normally when there is not a big load on them. So not sure if adding such a option will help. Only way to know is to add it and test if it works. 

If you enable the overload setting on the inverter itself it does switch immediately.  I seem to remember you having this happen when ever your aircon(or something else can't remember exactly what) started up and it swapped to grid when you still had the Axperts.

Think it should be doable. From my experience with AICC when swapping back to grid it is always immediately. Sometimes swapping to batt/pv mode might have a small delay but when grid fails it's immediate. 

The overload switch is part of the design(since you can turn it on and off) so hardware should also be safe we just want to make it more "smart" with AICC running it :)

Link to comment
Share on other sites

  • 5 months later...

So i've got this setting(23:Overload bypass) enabled on my Axpert MKS-5SK but it does not seem to switch to grid... Every so now and then my wife uses the microwave and the kettle at the same time and my load goes over 4kw, the inverter overloads and shutdowns... it then automatically restarts and we have power again. I was expecting it to switch to grid at that point but i may have something incorrectly configured.

These are my current settings. I am on the 72.60A patched firmware.

Settings.JPG.8a2989f46e73f46363a27117928dd7eb.JPG

 

It was the below spike that caused it to overload.

load.thumb.JPG.0868b93cf84e83c1c3148f2d6d92a69b.JPG

 

Battery volts seems ok

Battv.thumb.JPG.8e0ff0b00a71e7cbfa402cb29bf6386d.JPG

Have i mis-configured a setting? or have i not understood how this setting works.

 

 

Link to comment
Share on other sites

It's possible it can't switch fast enough. I had that with my multiplus back in the day, it can handle 200% for about a second, 120% for quite a bit longer, so if you slightly overload it, it has time to switch back, if you overload it to 200% it shuts down before it can switch.

Link to comment
Share on other sites

2 hours ago, PurePower said:

Have i mis-configured a setting? or have i not understood how this setting works.

Yes, your "Back to Grid Voltage" setting is set to 46 Volt, which is too low. Your voltage went down to 48 volts and never got close to 46 volts. Set the "Back to Grid Voltage" to 49 Volts and try it again. You will see it will change to grid. 

Link to comment
Share on other sites

1 hour ago, plonkster said:

It's possible it can't switch fast enough. I had that with my multiplus back in the day, it can handle 200% for about a second, 120% for quite a bit longer, so if you slightly overload it, it has time to switch back, if you overload it to 200% it shuts down before it can switch.

At 150% load my inverters would sit there sounding alarm bells, but kept going. I thought it was the fire alarm. In the mean time it was the wife switching on every plug she could find in the kitchen with the oven and stove going at the same time. 

Link to comment
Share on other sites

3 hours ago, Don said:

Yes, your "Back to Grid Voltage" setting is set to 46 Volt, which is too low. Your voltage went down to 48 volts and never got close to 46 volts. Set the "Back to Grid Voltage" to 49 Volts and try it again. You will see it will change to grid. 

Settings2.JPG.fa207a0d812e4a60a85519632b8e24e7.JPG

 

Awesomeness... This is why i love forums... there are always people willing to help and share their knowledge. Thank you @Don. I have changed it as per above and it now switches to grid when the voltage hits 49v. The overload bypass only applies when more than 4kw is requested. I tested this as well and the inverter throws fault code 7 and beeps, this is expected i think. 

What puzzles me is why when the "back to grid" voltage is set to 48v, it also shut downs the inverter and restarts... still confusing the hell out of me as my load is just under 4kw when it does this. It only works when it is set to 49v or above. Is it because the Nominal DC Input Voltage must be 48v as per the specifications of the Axpert?

 

Link to comment
Share on other sites

2 hours ago, PurePower said:

Settings2.JPG.fa207a0d812e4a60a85519632b8e24e7.JPG

What puzzles me is why when the "back to grid" voltage is set to 48v, it also shut downs the inverter and restarts... still confusing the hell out of me as my load is just under 4kw when it does this. It only works when it is set to 49v or above. Is it because the Nominal DC Input Voltage must be 48v as per the specifications of the Axpert?

Your voltage logging seems to be reporting whole volts. The inverter's DSP works on tenths of a volt. So that 48 V might really be 48.4 or even 48.9 V. So it doesn't actually cross the back to grid threshold. 

Link to comment
Share on other sites

8 hours ago, Coulomb said:

Your voltage logging seems to be reporting whole volts. The inverter's DSP works on tenths of a volt. So that 48 V might really be 48.4 or even 48.9 V. So it doesn't actually cross the back to grid threshold. 

Thanks, but still doesnt explain why the inverter shutsdown... There is enough battery volts to supply the load and we have not breached the 4kw threshold of the inverter...

Link to comment
Share on other sites

26 minutes ago, PurePower said:

 There is enough battery volts to supply the load and we have not breached the 4kw threshold of the inverter...

Yeah, it's supposed to be able to run 4 kW continuously. Maybe the load has a really bad power factor, and it's exceeding 5 kVA? That also seems unlikely. Maybe the battery voltage collapses when it reaches around 48 V, but if rescued at 49 V (where the internal resistance is a little lower) it's OK?

What is the capacity of your battery?

Link to comment
Share on other sites

9 minutes ago, Coulomb said:

Yeah, it's supposed to be able to run 4 kW continuously. Maybe the load has a really bad power factor, and it's exceeding 5 kVA? That also seems unlikely. Maybe the battery voltage collapses when it reaches around 48 V, but if rescued at 49 V (where the internal resistance is a little lower) it's OK?

What is the capacity of your battery?

emoncms.org is not accepting my decimals for the battery volts... i think it just drops it.

My battery bank capacity is 200ah.

Link to comment
Share on other sites

I am using Emoncms Local. The only time it drops the decimals is when the reading is say 54.0 Volt, it will only display 54, even if decimals are set at 1. But as soon as it goes up or down slightly, the decimals are back, i.e. 54.1 or 53.9 Volt.

Link to comment
Share on other sites

56 minutes ago, Don said:

I am using Emoncms Local. The only time it drops the decimals is when the reading is say 54.0 Volt, it will only display 54, even if decimals are set at 1. But as soon as it goes up or down slightly, the decimals are back, i.e. 54.1 or 53.9 Volt.

Hi Don. 

I had this behaviour also: It has to do with the locales settings:  Decimals should be a point (some countries use the comma).  After correcting the language setting it worked since then. 

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.

×
×
  • Create New...