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Axpert Inverters with Pylontech batteries


Paul Vermeulen
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I have up-graded to 4 x 3.5kW Pylontech batteries, 2 x 5kVa Axpert Inverter Chargers, and 22 Solar Panels with a total capacity of 6kW. I had problems at first with the back to grid and back to discharge settings, the voltage drops under load and the system goes into bypass mode too quickly. So I got the Raspberry Pi with the ICC software, magnificent program, but I still battle to get the correct settings, I would like to get the batteries down to 20% capacity before the system goes into bypass mode to justify the Lithium Ion batteries.

Please can someone advise what settings to use and where? I have Back to Grid at 48V, Back to Discharge at 50V, Floating Voltage 53.2V, Cut-off Voltage 47.5V I have been manually switching to bypass mode when the batteries get to about 50% but the other night I forgot to do this and the whole system shut down, bit of a nuisance! Of course with the extra 2 batteries I am assuming the load will be shared equally between them and the voltage drop under load will only be half of what it used to be! And I should get double the standby time too. I dream of being off the grid before the electricity system collapses.

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Hi Andy yes. Last night I was very disappointed the batteries were on 95% when they started to discharge, and by 9pm with an average of about 700W Discharge they went flat. However when I looked at the ICC Software the batteries were still on 65%. It showed less than 25% on the Axpert Inverters.

So I adjusted the Cutout Voltage on the inverter until the Axpert showed 65% battery capacity, this worked out at 45V, and all of a sudden the program showed that I had another 14 hours operation to get down to 20% DOD. So far today I have used 5.1kW of battery power, generated 16.2kW of solar power, and the batteries are 87% charged, I am sure that they will get to 100% before the discharge cycle starts! Not bad coming up to winter.

If you know how to get the ICC Program to override the inverter settings I will be very grateful.

 

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I also increased the maximum charging current since I now have double the amount of batteries. After providing electricity for the house I have seen the charge rate go up to 67 Amps, in theory it could go up to 120 Amps which is less than the recommended charge rate of 37A per battery. I just have to hope that the batteries do not go completely flat, like they did once before, with the cutout voltage so low.

 

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Cool - if you have the Pylon comms cable it makes everything a whole lot easier to manage. Then you can have ICC change between Solar and Battery based on the SOC from the Pylon BMS instead of doing it based on the Axpert's voltages.

4 hours ago, Paul Vermeulen said:

If you know how to get the ICC Program to override the inverter settings I will be very grateful.

To do that, you have to set the Axpert's voltage set points for Back to Grid and Back to Discharge lower/higher than usual so that they do not interfere with ICC (so that the Axpert does not switch by itself anymore). Then you have to set ICC to switch based on SOC and define your set points.

Here are the settings that I use

A1.jpg

A2.jpg

2 hours ago, Paul Vermeulen said:

Three of my batteries have been fully charged for over an hour, but the one is stuck at 86% 52V and is 3C hotter than the other batteries. Is this cause for concern? The overall charge is 96%, but I feel that they should all be 100% as a new system.

I think you need to balance your batteries as the battery that is not yet at 100% does not even receive any amps. I don't have the link at hand for doing that, but if you Google you should quickly find it.

 

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2 hours ago, wolfandy said:

Cool - if you have the Pylon comms cable it makes everything a whole lot easier to manage. Then you can have ICC change between Solar and Battery based on the SOC from the Pylon BMS instead of doing it based on the Axpert's voltages.

To do that, you have to set the Axpert's voltage set points for Back to Grid and Back to Discharge lower/higher than usual so that they do not interfere with ICC (so that the Axpert does not switch by itself anymore). Then you have to set ICC to switch based on SOC and define your set points.

Here are the settings that I use

A1.jpg

A2.jpg

I think you need to balance your batteries as the battery that is not yet at 100% does not even receive any amps. I don't have the link at hand for doing that, but if you Google you should quickly find it.

 

Thank-you for your advice! I will change my settings to work on the SOC from the ICC program. And will look for a program to balance the batteries, I did buy the "faulty" one about 6 weeks ago and only took delivery of it yesterday, so it could have discharged in storage.

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17 hours ago, Paul Vermeulen said:

Three of my batteries have been fully charged for over an hour, but the one is stuck at 86% 52V and is 3C hotter than the other batteries.

You should not be comfortable with that. I see in your screenshot battery 3 is half a volt lower compared to the others. How is that possible? Did you connect them in the right way? Can you make a picture of the connections?

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1 hour ago, RikH said:

You should not be comfortable with that. I see in your screenshot battery 3 is half a volt lower compared to the others. How is that possible? Did you connect them in the right way? Can you make a picture of the connections?

Last night was very good we got to about 5am before the ICC Software put us in bypass mode, and by about 8am we were back in Battery mode. I just need a little bit more power, maybe cut some trees down or get a few more panels. I am attaching a picture of my battery connections, and the data from last night.

Battery connections.jpg

Dashboard 2.jpg

Pylontech Data.jpg

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13 hours ago, wolfandy said:

You're welcome - happy to help

No software required for Pylon balancing. See Youtube video here

Thank you that looks simple enough, just means I will have to shut down my power for an hour or two! I will probably wait for tomorrow, do you see that the two older batteries are taking more current than the newer ones? But the voltage is fairly stable. All of the SOC lights are exactly the same.

 

Edited by Paul Vermeulen
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Well there must be something wrong with the measuring, otherwise it is not possible to get half a volt difference. Did you measure the voltages yourself as well?

Edit: are you sure the batteries are numbered 1 -> top, next 2, next 3 and the lowest 4?

There is however a change you should make: put the + cable to the inverter on the top battery and put the minus on the lower one so you can be sure current is shared even over the batteries.

Edited by RikH
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1 hour ago, Paul Vermeulen said:

just means I will have to shut down my power for an hour or two!

Don't you have a changeover switch installed that you can simply bypass the inverters for a while and run off utility in the meantime?

58 minutes ago, RikH said:

There is however a change you should make: put the + cable to the inverter on the top battery and put the minus on the lower one so you can be sure current is shared even over the batteries.

+ 1

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21 hours ago, Paul Vermeulen said:

Three of my batteries have been fully charged for over an hour, but the one is stuck at 86% 52V and is 3C hotter than the other batteries. Is this cause for concern? The overall charge is 96%, but I feel that they should all be 100% as a new system.

OK, so the reason one battery is hotter than the other is because it is balancing. This is normal.

This is also typical for a new system, the batteries we receive from the suppliers very often aren't internally balanced. I don't know if this is a new thing (maybe they can't do this at the factory anymore due to high volumes), but be that as it may, I've seen this numerous times now with more than one manufacturer. And my answer to this is to simply ignore it. It goes away after about two weeks of use. Cycle the batteries daily, take them down to at least 80% SoC, and when you recharge them, hold them at 100% for some time to give the balancers time to work.

If you have some way to get per-cell voltages, that is even better. For example, newer BYD batteries (also the new 24V pylontechs) combined with Victron systems can now communicate the lowest and highest cell voltage and even log it for monitoring. A BYD battery will signal a stop-charge condition if any cell goes above 3.8V. I've seen at least one case where a battery had a low cell at 3.35V and a high cell at 3.8V. Since the balancers generally start running above 3.45V per cell, you need to hold the battery at a voltage high enough to have at least some cells above that voltage... so again, it helps if you know what they are. If not... then just hold at 100% for a few hours a day.

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5 hours ago, plonkster said:

OK, so the reason one battery is hotter than the other is because it is balancing. This is normal.

This is also typical for a new system, the batteries we receive from the suppliers very often aren't internally balanced. I don't know if this is a new thing (maybe they can't do this at the factory anymore due to high volumes), but be that as it may, I've seen this numerous times now with more than one manufacturer. And my answer to this is to simply ignore it. It goes away after about two weeks of use. Cycle the batteries daily, take them down to at least 80% SoC, and when you recharge them, hold them at 100% for some time to give the balancers time to work.

If you have some way to get per-cell voltages, that is even better. For example, newer BYD batteries (also the new 24V pylontechs) combined with Victron systems can now communicate the lowest and highest cell voltage and even log it for monitoring. A BYD battery will signal a stop-charge condition if any cell goes above 3.8V. I've seen at least one case where a battery had a low cell at 3.35V and a high cell at 3.8V. Since the balancers generally start running above 3.45V per cell, you need to hold the battery at a voltage high enough to have at least some cells above that voltage... so again, it helps if you know what they are. If not... then just hold at 100% for a few hours a day.

The batteries have balanced already after two days, I did notice that the older two batteries take a higher charge when they start charging, but the parameters per battery are exactly the same, SOC, Health, Voltage. I am very happy, just need some sun, sounds like we are going to have another wet patch this week!

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18 hours ago, Paul Vermeulen said:

I am attaching a picture of my battery connections...

Battery connections.jpg

I'm surprised no-one noticed that the connections are wrong. You need one of the battery cables (orange or black) to come from the bottom battery module (and the other one from the top module, as it is now). This will help to share the current load more evenly between modules.

Edit: as it is now, the bottom module will contribute much less current to powering the loads, and will receive less charge current as well. The top module will do most of the work, and will degrade more quickly as a result.

Edit 2: note how the bottom module is showing three bars, when the others are showing two. That's at least in part because it's not seeing as much of the load.

Edited by Coulomb
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22 minutes ago, Coulomb said:

I'm surprised no-one noticed that the connections are wrong. You need one of the battery cables (orange or black) to come from the bottom battery module (and the other one from the top module, as it is now). This will help to share the current load more evenly between modules.

Edit: as it is now, the bottom module will contribute much less current to powering the loads, and will receive less charge current as well. The top module will do most of the work, and will degrade more quickly as a result.

Edit 2: note how the bottom module is showing three bars, when the others are showing two. That's at least in part because it's not seeing as much of the load.

I did notice when connecting the new batteries that the negative should feed from the bottom battery to regulate the current flow, but the cable was too short. I will reroute it or make up a new cable to solve this issue!

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22 hours ago, RikH said:

There is however a change you should make: put the + cable to the inverter on the top battery and put the minus on the lower one so you can be sure current is shared even over the batteries.

 

4 hours ago, Coulomb said:

I'm surprised no-one noticed that the connections are wrong.

Haha!

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