Jump to content

UPS Backup with Axpert Inverter and Pylontech Battery


Paul Vermeulen
 Share

Recommended Posts

I have just done an Axpert 5kW Inverter only with a 3.5kW Pylontech Battery, that will go into bypass mode if there is a power failure and hopefully feed the house for a couple of hours. Please can someone advise if I have the correct settings, I set the maximum charge rate to 20A (25A was not an option), Bulk Charging Voltage 53.4V, Floating Voltage 53.2V, Back to Grid Voltage 52V, battery cutoff voltage 44V it is working correctly. Do I need to connect the communications cable in this application or will the Battery Management System take over? Thanking you in advance for your advice.

Link to comment
Share on other sites

14 minutes ago, Paul Vermeulen said:

I set the maximum charge rate to 20A (25A was not an option),

25 A is correct for 1 US2000 battery module (and 1 inverter). US3000s can be charged at 37 A, so use 30 A.

15 minutes ago, Paul Vermeulen said:

Bulk Charging Voltage 53.4V,

Please no! 52.5 V.

16 minutes ago, Paul Vermeulen said:

Floating Voltage 53.2V,

Your battery will be floating 90% of the time. Use 51.8 V for better battery life.

17 minutes ago, Paul Vermeulen said:

Back to Grid Voltage 52V,

This should obviously be lower than your float voltage, so try 51 V.

18 minutes ago, Paul Vermeulen said:

battery cutoff voltage 44V

You will be running this till the battery runs out, i.e. this is not an emergency save the silver thing, it's a routine discharge limit. So I'd experiment but start with 45 V or more. You should have the last LED still on (6 SOC LEDs; I assume that 1 LED ≅ 17% SOC, bear in mind I've never used a Pylontech). Better yet if you can read the SOC from the battery, aim to turn off at about 20% SOC.

22 minutes ago, Paul Vermeulen said:

hopefully feed the house

One US3000 is quite light to feed "the house", unless you have very light loads. Hopefully, your geyser and other high power draw elements won't be on the inverter's output (so they'll not work during load shedding / outage).

24 minutes ago, Paul Vermeulen said:

Do I need to connect the communications cable in this application or will the Battery Management System take over?

The BMS can only "take over" by disconnecting the battery totally. That's a bit of a gamble with the inverter's safety. But I'll leave others to comment on this.

Link to comment
Share on other sites

3 hours ago, Coulomb said:
3 hours ago, Paul Vermeulen said:

Do I need to connect the communications cable in this application or will the Battery Management System take over?

The BMS can only "take over" by disconnecting the battery totally. That's a bit of a gamble with the inverter's safety. But I'll leave others to comment on this.

Depending on which Axpert model you have, it cannot process the Pylon BMS data directly. Hence @Coulomb 's comment that the only feature/function that the BMS will provide is disconnecting the battery for self-protection. But this should only be your emergency last resort (as then your complete system will also shut down).

To make use of the accurate SOC data that the Pylon BMS is providing (rather than the crude Axpert voltage guess-timate), you will need something like the ICC software and their Pylon Comms cable. But if you are only planning to run it purely as a backup system, I do not believe that it will add any real value to you. 

3 hours ago, Coulomb said:
3 hours ago, Paul Vermeulen said:

battery cutoff voltage 44V

You will be running this till the battery runs out, i.e. this is not an emergency save the silver thing, it's a routine discharge limit. So I'd experiment but start with 45 V or more. You should have the last LED still on (6 SOC LEDs; I assume that 1 LED ≅ 17% SOC, bear in mind I've never used a Pylontech). Better yet if you can read the SOC from the battery, aim to turn off at about 20% SOC.

I would also definitely raise it to something higher than 44V. At 22% SOC my Pylons were around 48.6V last night. I have mine set to 46.5V - but have never actually drained my Pylons down to that voltage. I would guess that your current 44V is significantly below the recommended 80% DOD for the Pylon, which means that your expected lifetime cycles will drop. I have never looked at voltage / SOC relation in detail, but my guess would be that somewhere between 48V and 49V. Maybe start with 49V and see (a) if it still gets you through loadshedding without your system shutting down and (b) how many LEDs are still on when your system shuts down

3 hours ago, Coulomb said:
3 hours ago, Paul Vermeulen said:

hopefully feed the house

One US3000 is quite light to feed "the house", unless you have very light loads. Hopefully, your geyser and other high power draw elements won't be on the inverter's output (so they'll not work during load shedding / outage).

+1

If you currently get to the point that your systems shuts down during loadshedding because your Pylon has been discharged down to your current 44V Battery Cutoff Voltage, then you need to add another Pylon or reduce your load during loadshedding.

Also please keep in mind that a single Pylon does not like to be discharged by more than 37A - which translates to approx. 1800W. Even though your Axpert can provide more power than that, drawing more than 1800W for longer periods will in the long run hurt your Pylon

Link to comment
Share on other sites

Thank you for the feedback. The electrician wired the inverter circuit through a changeover switch so that it can bypass the inverter in normal operation, not something that I would do because it defeats the object of having the inverter as a UPS supply. I did check the usual load, which is less than 1kW, and advised them to replace all their CFL bulbs with LED's, and to not plug any heavy current appliances into the inverter circuit, but sadly I know that the temptation will be too high. As a backup battery it should last a long time, I will reduce the bulk and floating voltages to stop it from over-charging. And the reason I lowered the cut-off voltage is because the inverter was giving an Alarm 04 as soon as it went into Battery mode. I will try increasing it to a level where it doesn't think the battery is flat.

Long term they want to add to the batteries and possibly add solar panels, at that stage I will definitely recommend the ICC software.

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.

 Share

×
×
  • Create New...