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bcowley avatar image
bcowley asked

Turn off AC input to cycle Pylontech batteries in UPS role

We have recently setup a MultiPlus II, with 2 Pylontech US3000C batteries, plus Cerbo GX, for backup power at our (remote) community radio station. We understand the batteries should not be left 100% charged, but partially discharged maybe twice per week. The Multi uses the Pylon BMS and DVCC mode is enabled.

So far I've set up root access to the Cerbo. Can a script write to a register in order to control the AC Input relay? Please let us know the register details to achieve this, or if there is a better method.

Thanks.


Pylontech
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Alexandra avatar image Alexandra ♦ commented ·

@bcowley

I have a tack on question, where does the understanding of not keeping the Pylontec at 100% SOC come from?

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bcowley avatar image bcowley Alexandra ♦ commented ·

Thanks for that question! The company that sold us this equipment said we should partially discharge these batteries on a regular basis. However there's relatively little on the internet about optimum use of LiFePo4 batteries in a UPS application. The VRM portal shows that the BMS is doing minimal cycling - but the SOC is always reported as 100%. Maybe it's enough?

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2 Answers
hominidae avatar image
hominidae answered ·

..if you are running this setup in ESS mode, you could simply force a discharge of the batteries by setting the Grid-Point to a negative value, resulting in a Grid-export (if allowed by your network operator).

If you want to do this programmatically, I suggest to look into Node-Red. It is part of the VenusOS-Large Image and can be installed on the Cerbo.

You can as well run NodeRed on a separate RPi or in a Container/VM on a NAS, in your network...also nice for testing before changing a production system.

There are separate, special Nodes available for integrating with a Victron System, but it can be done with just using MQTT as well (enable Modbus and MQTT Services on your Cerbo).


Have a look here: https://www.victronenergy.com/live/venus-os:large

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wkirby answered ·

If you are not using any assistants then you could use this method:
https://www.victronenergy.com/live/drafts:acin_ignore_timer_using_ccgx_gen_start_stop_example

Then use register 806 or 807 to write to a CerboGX relay.

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