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Axpert MKS 5KVA battery equilizing


Wilco
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The Axpert MKS inverters are a nice and relatively trouble free inverter. The only thing lacking is battery equalizing in the MPPT or inverter.

Do any one know of a solution to this problem? I install mainly off grid systems in the rural areas en every now and again I get a call that the batteries does not last. Then I have to load my 64v charger and a generator and go sit there for hours waiting for the batteries to equalize and some systems are over 500km from me.

I would appreciate any insight and or solutions for this

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1 hour ago, Wilco said:

The only thing lacking is battery equalizing in the MPPT or inverter

Trouble free? This thing you mention is one of the big troubles people have with it! :-P

We've discussed that to death on this forum. The options are to 1) spend more time at absorption voltage (if possible), 2) install a better external charge controller and stop using the one inside the inverter, 3) use an external charger, as you've done. Some of the versions of the firmware has a bug where it goes to float too soon, exacerbating the problem, so just loading the patched firmware (search this site for details) may already help.

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Hi Wilco

You have two options:

  1. Use batteries that fit the Axpert's charging profile
  2. Use a separate SCC that can deliver an equalising charge

Otherwise you are destined to cover many km in you bakkie with the charger on the back. 

I have had 2 years of trouble free Axpert use but the batteries I have fit the charging profile.

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Thanks Guys

I just downloaded the patched firmware, going to try it. According to another post, this version has the ability now to do equalizing at program section 33 to 37 and 39.

don't know how true it is. Will give it  a go in the next few days and see if it's true

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1 minute ago, Wilco said:

According to another post, this version has the ability now to do equalizing at program section 33 to 37 and 39.

Just be careful. The newer Axperts have different hardware and you may just fry a machine. Program 32 is to increase the absorb charge time. The newer models can go to 64V but ensure that the inverter you trying to equalise with can actually safely charge at those elevated voltages.

The batteries you having to equalise are these Trojans? If not I would guess that your problems are not due to the Axpert but either battery related or due to too high a draw and too few panels.

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10 minutes ago, Chris Hobson said:

Just be careful. The newer Axperts have different hardware and you may just fry a machine. Program 32 is to increase the absorb charge time. The newer models can go to 64V but ensure that the inverter you trying to equalise with can actually safely charge at those elevated voltages.

The batteries you having to equalise are these Trojans? If not I would guess that your problems are not due to the Axpert but either battery related or due to too high a draw and too few panels.

Would it actually allow you to make that update?

That would be really bad...

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The batteries are 8 x 12v 200Ah Pantzer AGM batteries that I bought from Solaire. Panels are enough, running 12 x 250 ecosol panels. Current draw is the same for the last year. System is properly sized. batteries shows full at 10 in the morning already. Sure they just need a equalize then they will be good again. The inverters are 1 year old Mercer MKS units and according to @Coulomb 's write up, the firmware are for the MKS inverters with single MPPT. Surely when the firmware changes the programming sections might also change then

Edited by Wilco
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The occasional prolonged absorption charge on an agm should be enough to sort them out. I had a problem with my agms with a >3% midpoint deviation at absorb, and by giving it a very thorough charge for several days in a row the problem is completely resolved. No equalisation required, it's not good for an agm either.

Sent from my GT-I9195 using Tapatalk

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54 minutes ago, Gnome said:

Would it actually allow you to make that update?

That would be really bad...

It appears from @Coulomb's warnings that there is no check to see whether the hardware can implement the firmware changes - what you get buying a R10k inverter. They do warn you in the manual to contact a sales representative before charging at these elevated values. I wonder whether it is so that they can give you the repair representative's after hours phone number?

 

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The high voltage required during equalization causes gassing and loss of electrolyte, this is no problem in a flooded cell where you can replace the lost electrolyte but very bad for AGM where it is lost forever.

I suggest installing a battery balancer which is the AGM response to equalization, and occasional prolonged absorption charge at the recommended voltage as suggested by @plonkster

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I was actually amazed how nicely my batteries recovered. There was a bug in one of the early 2.0x versions of the CCGX firmware and it would go to float too easy (the same problem the Axperts have). As is often the case, I told myself I would fix it "tomorrow" and this went on for a few weeks. By the time I did something about it the batteries (which are well into their midlife by now) started to show a significant midpoint deviation: Sulphation probably started to set in on a cell somewhere. I thought about a balancer... but again... "tomorrow". In the mean time I made sure the batteries are fully charged each day, holding them at absorb until well past 100% (as measured by the BMV) with the tail current well below 1% of capacity. As I repeatedly did this, the deviation started to get less by the day and eventually disappeared. No balancer... no equalisation. :-)

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