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Axpert MKS 3000 24V Overload Bypass Enabled/Disabled


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5 minutes ago, PeterGutti said:

some countries use the comma

Thanks Peter, I will have a look. The "comma" is for words, decimal point is for mathematical figures, according to me, :)

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13 hours ago, PurePower said:

My battery bank capacity is 200ah.

I don't know much about deep cycle lead acid batteries. My understanding is that you should not charge them much faster than C/7, or discharge them faster than some other limit, which I thought was about C/2 or C/3. 4000W at 48 V with 93% efficiency is some 90 A, which is heading towards C/2. I would not expect the voltage to collapse at that load, but I would not be surprised if the battery voltage at the Axpert terminals did a bit of a dip that causes the Axpert to draw more power to maintain the load, causing more voltage drop. Enough for the Axpert to declare overload.  All this could happen so quickly that the Axpert display may not show it, let alone software monitoring. This would be more plausible if your battery cables were on the thin side, say 25 mm^2 or less. As I type this however, the above scenario would probably result in a different error code, related to battery and not overload. It's still plausible, I think, but less likely than I thought. So yes, a bit mysterious. 

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Charge deep cycle lead acid batteries at 10%, max 13% of C20 ah rating.

Reading this thread now for a few days, maybe a faulty cell on one of the batteries causing the volts to drop so fast, Axpert switching off?

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13 hours ago, PeterGutti said:

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. 

How does locale setting apply to emoncms.org?

Nevermind, i changed the locale from the machine i am posting from to emoncms.org and it now posts decimals.

Thanks.

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24 minutes ago, PurePower said:

How does locale setting apply to emoncms.org?

It probably affects how a string is formatted, for example, here is a quote from the man page for printf(3) (unix C-lib implementation of printf), which is often copied by other implementations (eg the python one):

Quote

 

       For  some  numeric  conversions  a radix character ("decimal point") or
       thousands' grouping character  is  used.   The  actual  character  used
       depends  on  the  LC_NUMERIC part of the locale.  The POSIX locale uses
       '.' as radix character, and does not have a grouping character.  Thus,

               printf("%'.2f", 1234567.89);

       results in "1234567.89" in the POSIX locale,  in  "1234567,89"  in  the
       nl_NL locale, and in "1.234.567,89" in the da_DK locale.

 

It's a bug in the software really, you shouldn't use locale-dependent format strings :-)

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On 3/16/2017 at 8:54 AM, The Terrible Triplett said:

Charge deep cycle lead acid batteries at 10%, max 13% of C20 ah rating.

Reading this thread now for a few days, maybe a faulty cell on one of the batteries causing the volts to drop so fast, Axpert switching off?

So i had my batteries individually load tested today. I had them disconnected from last night and the battery balancer removed. We load tested after 12 hours and it was comfortably holding over 12v when pulling 100A for 10s. We reduced the load(not sure by how much) after 10s and voltage was still over 12v. We performed this test to each battery individually and we could not find a problem. When the load was removed, it went back to around 13.1v. I have the Narada 12NDT200 AGM batteries. So I don't have any dead cells. 

 

On 3/16/2017 at 0:48 AM, Coulomb said:

I don't know much about deep cycle lead acid batteries. My understanding is that you should not charge them much faster than C/7, or discharge them faster than some other limit, which I thought was about C/2 or C/3. 4000W at 48 V with 93% efficiency is some 90 A, which is heading towards C/2. I would not expect the voltage to collapse at that load, but I would not be surprised if the battery voltage at the Axpert terminals did a bit of a dip that causes the Axpert to draw more power to maintain the load, causing more voltage drop. Enough for the Axpert to declare overload.  All this could happen so quickly that the Axpert display may not show it, let alone software monitoring. This would be more plausible if your battery cables were on the thin side, say 25 mm^2 or less. As I type this however, the above scenario would probably result in a different error code, related to battery and not overload. It's still plausible, I think, but less likely than I thought. So yes, a bit mysterious. 

According to the Narada 12NDT200 data sheet, the maximum charge limit is 50A. I've set the Axpert to limit to 40A since i've had them and the installer also recommended 40A, whether on solar or utility. My battery cables are 35mm^2 and about 1m in length. Now i don't believe an overload occurred as i don't have to breach the 4kw threshold for the Axpert to shut down completely and reboot. When i do breach the 4kw threshold, then an overload occurs(plenty beeping, red light, and warning/error icon on display) and it switches to utility. This is starting to make me believe that there is a firmware issue with version 72.60A because if memory serves me correctly when i had version 72.40(original version when i bought the inverter), this was never an issue.

Is it possible for you to have a look at this?

Is it also possible to downgrade to a previous firmware version? as this will confirm it entirely.

 

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21 minutes ago, PurePower said:

So i had my batteries individually load tested today.... 

 This is starting to make me believe that there is a firmware issue with version 72.60A... 

Is it possible for you to have a look at this?

Is it also possible to downgrade to a previous firmware version? as this will confirm it entirely.

Excellent; good to eliminate the battery as a possible problem. 

It's certainly possible that there is a bug in the patched firmware not present in the original. I'll look into it. 

I'm not aware of any problems downgrading to an earlier firmware version, though others have claimed this. 

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Just now, Coulomb said:

I'm not aware of any problems downgrading to an earlier firmware version, though others have claimed this. 

Do i just follow the same upgrade process and use the old firmware file? Do you have a copy of the 72.40 firmware?

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9 minutes ago, PurePower said:

Do i just follow the same upgrade process and use the old firmware file? Do you have a copy of the 72.40 firmware?

Yes, just use the old firmware file. I always include the original firmware that the patch is based on, in case it's necessary to go back, with the download instructions. In this case, that would be 72.60. But if you want to test 72.40 specifically (perhaps that's the last one you know worked for you), then I happen to have some older firmwares (including 72.40) available here: http://forums.aeva.asn.au/forum_posts.asp?TID=4332&PID=59274&title=pip4048ms-inverter#59274 .

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@PurePower: your first post on page 2 mentions your "Axpert MKS-5SK"; this is a true Voltronic Manufactured 5 kVA inverter with an MPPT Solar Charge Controller, right? I had a terrible thought when I noticed the title of this topic ("Axpert MKS 3000 24V Overload Bypass Enabled/Disabled"), since the patched firmware certainly won't work with a 24 V inverter. You would certainly have noticed that all the settings were for a 48 V battery, but if yours is one of the PWM (non MPPT) models, then it's possible that the patched firmware might appear to work, but have subtle errors. But if official firmware 72.40 works for you, then patched 72.60 should work.

Did your inverter come with 72.40 installed?

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12 hours ago, Coulomb said:

@PurePower: your first post on page 2 mentions your "Axpert MKS-5SK"; this is a true Voltronic Manufactured 5 kVA inverter with an MPPT Solar Charge Controller, right? I had a terrible thought when I noticed the title of this topic ("Axpert MKS 3000 24V Overload Bypass Enabled/Disabled"), since the patched firmware certainly won't work with a 24 V inverter. You would certainly have noticed that all the settings were for a 48 V battery, but if yours is one of the PWM (non MPPT) models, then it's possible that the patched firmware might appear to work, but have subtle errors. But if official firmware 72.40 works for you, then patched 72.60 should work.

Did your inverter come with 72.40 installed?

Yes got the Axpert 5kva with the MPPT controller. I hijacked this topic as my issue is also around the overload/bypass function. I did not want to create another topic when they are sort of related.

I'm going on holiday for about a week, i'll revert the firmware when i get back and post the results.

Do i need to revert the SCC firmware as well? It was on version 1.24

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1 hour ago, PurePower said:

Do i need to revert the SCC firmware as well? It was on version 1.24

No, I don't think it will matter. Perhaps the next thing to try, if there is no difference, just to be absolutely sure. 

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  • 2 weeks later...

So i've tried the following combinations of firmware...

Firmware
DSP   SCC
72.40 4.1
72.40 1.24
72.60a 1.24
72.60a 4.1
72.70b 4.1

And all of them produced the same result... i felt disappointed now but after the trip on the 72.70b firmware, my inverter failed to start up. I thought i popped it after all the testing and it was evening time now, so no PV power either.

My BMV702 still said batteries are at 98% SOC and my inverter is still failing to switch on. Then i took the cover off and measured the DC voltage going into the inverter and it was non existent... So i was puzzled but soon realised i have this dc breaker. 

58e9434c55e0f_100ADCbreaker.jpg.77dff863e0fc08a7e148fe32ba6b1981.jpg

Now when the trip happens, this breaker doesn't actually flip the switch to the off position, it just trips but on the last occasion the breaker had to be manually reset. I found this suspicious. Then i performed another test but touching the body of this breaker and when the inverter shut down, i felt a click at this breaker. Finally i understood what was going on. Clearly this breaker is not truly rated at 100A, or maybe it is and the surge power i'm drawing is over 100A and the breaker disconnects the batteries from the inverter for that second making the inverter shut down and restart when the breaker resets automatically. Luckily for me it did not reset automatically on the last test.

I'm feeling so embarrassed as i'm typing this post, i was truly being a chop all this time. 

@Coulomb, @plonkster, @Don, @The Terrible Triplett, thanks so much for responding to my questions. It is much appreciated!

 

I think its end of life for this breaker as it was used in my older 3kw setup. Time to upgrade. Any recommended amp size i should look for? 200A for the Axpert MKS 5KVA 48v?

I looked at eBay and came across this:

http://www.ebay.com/itm/Bussman-187-Series-Blue-Sea-7149-DC-Circuit-Breaker-Surface-Mount-200-Amps-/172382934068?hash=item2822d2d434:g:ftkAAOSwDmBY3Ylc

Any good? 

Can anyone recommend a local supplier or someone selling on this forum?

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19 minutes ago, PurePower said:

200A for the Axpert MKS 5KVA 48v?

200 Amp is too high. You have a 4000 W Inverter at 48 V = 83 Amps. You add 25% which is 20,8 amps = 103.8 Amp. You get 100 Amp breakers (too low) and then 125 Amp breakers. Therefore you go to next highest number which is 125 Amp. That is what you should be looking at. 

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3 minutes ago, Don said:

200 Amp is too high. You have a 4000 W Inverter at 48 V = 83 Amps. You add 25% which is 20,8 amps = 103.8 Amp. You get 100 Amp (too low) and then 125 Amp breakers. Therefore you go to next highest number which is 125 Amp. That is what you should be looking at. 

Thanks, will look for this size. 

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That breaker looks too small to reliably break 100 A DC. AC perhaps, but not DC over 24 V. I use 100 A HRC 38 mm diameter fuses (positive and negative) in large holders that can be used as isolators. 100 A fuses that size don't nuisance trip on minor surges. These will cost considerably more than those dinky breakers, but it's safety equipment, so you pay it. 

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5 hours ago, PurePower said:

That doesn't look like a genuine Bussmann product to me, without checking. The "Buss®" looks wrong. They always seem to use the full name, and one of a few logos. 

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On 2017/04/08 at 10:51 PM, Don said:

200 Amp is too high. You have a 4000 W Inverter at 48 V = 83 Amps. You add 25% which is 20,8 amps = 103.8 Amp. You get 100 Amp breakers (too low) and then 125 Amp breakers. Therefore you go to next highest number which is 125 Amp. That is what you should be looking at. 

Just a thought... Should the DC breaker not be sized according to both the inverter size and battery cable size? Ultimately you are trying to protect your cables from not heating up and causing a fire.

That being said, i've got 35mm^2 DC cables which should be good for 105A continuous draw/ 200A surge which the inverter can't pull anyway... My thinking was to get a 120/125A as you suggested.

 

On 2017/04/09 at 4:24 AM, Coulomb said:

That doesn't look like a genuine Bussmann product to me, without checking. The "Buss®" looks wrong. They always seem to use the full name, and one of a few logos. 

Looks like their branding changed. I've checked their website and datasheets. Seems like these Bussmann product range has the new "Buss®" logo.

http://www.cooperindustries.com/content/dam/public/bussmann/Transportation/Resources/catalog_pages/BUS_Tns_Series_187_MRCB.pdf

 

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7 hours ago, PurePower said:

Should the DC breaker not be sized according to both the inverter size and battery cable size? Ultimately you are trying to protect your cables from not heating up and causing a fire.

Yes, the breaker is mainly there to protect your cables, but at the same time your batteries and inverter. You don't want to draw 180 Amps from your batteries just because you have thick cables and they don't get hot. You would probably pop the inverter or bend some plates in your battery. :)

That is why I calculate the maximum the inverter should be able to handle and add 25% for spikes. Anything above that, it should trip or blow a fuse, because then something is wrong. 

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1 hour ago, pilotfish said:

...he said bracing for the backlash! 

Lol. The day I went and bought all my stuff at ACDC for my setup, I asked for a 125A DC CB for my batteries. They have 3-4 "Consultants" behind a counter to assist noobs like me. I dealt with the guy before and he seemed to know what he was talking about, so I always went back to him. He asked me do I just want a standard CB or a High quality one. I said give me the high quality one. He gave me a Gewiss AC CB. I told him I wanted a DC breaker, he said, they are rated 50 VDC per pole as well. They apparently have massive buzz bars on the inside and that is why they are so expensive. So I took it. I said what about my Solar CB? I need a CB for live and neutral that would be between 100-110 VDC. He said no problem, then you use a Gewiss 4 pole CB. 2 poles for live and 2 poles for neutral. That would take the voltage up to 100 VDC. But he told me to connect the poles in series. In at the top, out at the bottom and in at the top on the one next door. The same with neutral. Therefore you end up on the the 4 pole CB with only one live and one neutral on the bottom or output side. I did it, works like a bomb. 

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43 minutes ago, pilotfish said:

commonly available 63amp 4pole DC CB

Microcare uses those common AC-rated breakers on their MPPTs. I'd like to think they did their homework, and I think the breakers are rated 600V, 63 amps. I vaguely recall a rule of thumb that says it's good for the same current at 10% of the DC voltage... though I may be way off base here.

Ionisation voltage of air is 3MV per meter. AC needs to recreate the arc every half cycle. DC has the benefit of a lower resistance path of ionised air. I have a gut feeling with enough info, you should be able to derive a thumb-rule by finding the ratio between the arc-over voltage and the arc-sustaining voltage. Anyone?

5 minutes ago, Don said:

But he told me to connect the poles in series.

Yup. When the breaker opens it creates twice the air-gap. Old trick I also remember from school.

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