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netstrider

Axpert KING-5000M & Battery Question

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I was wondering if anyone is using this inverter with Lithium Iron Phosphate batteries. According to the manual only lead-acid should be used, yet I have heard some people are using them with custom charging modes.

Even then, is the built-in charge controller not going to charge as per lead-acid charging methods?

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4 hours ago, netstrider said:

I was wondering if anyone is using this inverter with Lithium Iron Phosphate batteries.

Plenty (not including me).

Quote

According to the manual only lead-acid should be used

? Where does it say that?

Quote

Even then, is the built-in charge controller not going to charge as per lead-acid charging methods?

Yes, but fortunately LFP batteries are very easy to charge, and charging as if it was lead acid works pretty well. There is the issue of the very flat voltage versus state of charge curve, but it can largely be worked around. And of course, the dreaded premature float bugs, and lately dips and freezes (PV not charging the battery for some time, or until the end of the day).

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I could not find the difference between the KING 5000M and the KING 5000K.

I am using the AXPERT KING 5K with 2 x Pylontech US3000. This works great after I upgraded the firmware to 71.86 and the PYL option was available. The BMS controls all battery related parameters in the inverter. There is only a minor issue with the setting of the charge current because this setting limits the solar current to the same value. But this will not come into play since you only want backup power. 

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4 hours ago, Coulomb said:

Plenty (not including me).

? Where does it say that?

Yes, but fortunately LFP batteries are very easy to charge, and charging as if it was lead acid works pretty well. There is the issue of the very flat voltage versus state of charge curve, but it can largely be worked around. And of course, the dreaded premature float bugs, and lately dips and freezes (PV not charging the battery for some time, or until the end of the day).

image.png.428d4805434e59f63af1390ecf45bde9.png

Both here - http://inverexcustomercare.com/wp-content/uploads/2018/06/APT-Axpert-KING-3KW5KW-manual-20180112B.pdf

And here (Kodak which I presume is also Axpert)

https://solaradvice.co.za/wp-content/uploads/2019/07/Axpert-KING-manual-NEW.pdf

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2 hours ago, MJS said:

I could not find the difference between the KING 5000M and the KING 5000K.

I am using the AXPERT KING 5K with 2 x Pylontech US3000. This works great after I upgraded the firmware to 71.86 and the PYL option was available. The BMS controls all battery related parameters in the inverter. There is only a minor issue with the setting of the charge current because this setting limits the solar current to the same value. But this will not come into play since you only want backup power. 

Not sure of the K, but I know the M is, presumably, for modular in that it can run parallel.

From the datasheet I have only the 3kVa is not M, but P.

image.thumb.png.30d0e26593e135c5e14c246fe28799a2.png

Well yes, and no. I do intend getting PV later on.

Does this unit check PV first before relying on mains AC? For example, if I have 1kW coming from PV but need 2kW will it share the load or switch completely to mains?

Edited by netstrider

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On 2020/02/14 at 7:54 PM, netstrider said:

Well spotted re the lead acid batteries in the use manual. Could it be an entry inherited from an older version of this or another manual, that was never updated?

As of yesterday I am using an Axpert King 5K inverter with 2x Pylontech US2000 li-ion batteries. This seems to be a common pairing and given the attachment I've included here, one that Pylontech supports.

I made a communication cable to run between my inverter and batteries using the instructions in the attachment. The only thing it omits, without which the cable doesn't help, is that one has to lift the first dip switch on the battery to set the baud rate to 9600. I found that piece of information on this forum somewhere, which is how I signed up ;)

Pylontec Axpert VMIII-KING Configuration (used for cable, set battery dip switches to 1000).pdf

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On 2020/02/15 at 3:54 AM, netstrider said:

image.png.428d4805434e59f63af1390ecf45bde9.png

This is a very old piece of text. So it could well be that they didn't bother to update it for the post lead acid era.

I think they're trying to say "don't be stupid and try to recharge a non-rechargeable battery, it will likely burst". With the sweeping implication that all rechargeable batteries are lead-acid.

It could also be interpreted this way: IF you are using a lead acid battery, make sure it's a deep cycle type, not any of the other types of lead acid battery (such as a starter battery or marine type). This seems less likely, since these aren't likely to burst as a result of not being deep cycle types.

I would just ignore it.

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@MJS

On 2020/02/15 at 4:25 AM, netstrider said:

Not sure of the K, but I know the M is, presumably, for modular in that it can run parallel.

No, the M is for MPPT, the P is for PWM. I've not come across the PWM model before. The Voltronic Power and MPPSolar web sites don't mention them. Perhaps the 3000P model is specially made for Mecer. Or it's a new model and Mecer are quicker to update their web page than the others.

On 2020/02/15 at 4:25 AM, netstrider said:

Does this unit check PV first before relying on mains AC? For example, if I have 1kW coming from PV but need 2kW will it share the load or switch completely to mains?

The Axpert Kings use a double conversion design. That is, in line mode (different to line mode on so far all other Axperts), AC-in to AC-out goes via an AC-DC converter, then a DC-AC converter. Battery and/or PV power blend at the DC point.

So yes, in line mode, if 2 kW is needed and only 1 kW is available from PV, the other 1 kW will come from mains.

But if you need 7 kW and 4 kW is available, because the 7 kW exceeds the rating of the inverter, it will take all 7 kW from the mains. It will then be in bypass mode (different to line mode on the Axpert King). But presumably, this will be a rare and short-duration event, assuming that your inverter(s) is (are) sized to handle most loads.

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17 hours ago, Ryanwb1 said:

Whats the main difference between the Axpert Mecer King and the Mecer MKSII?

As per the above post, the Axpert King is double conversion, so it is able to blend AC-in power with PV and battery power. The MKS II is able to blend only PV and battery power. If it has to switch the loads over to AC-in, all of the load power will come from AC-in.

The Axpert King has a 145 V max MPPT, so you need strings of 2S panels (or 3S of 60 cell panels). The Axpert MKS II has a 450 V max MPPT, so you have to wire at least about 6 panels in series.

The King has the removable display; the MKS II does not.

Recently manufactured King models have the ability to connect directly to the BMS of a PylonTech battery; the MKS II does not.

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