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muhkel avatar image
muhkel asked

Why Cyrix-Li-Charge turns off my MPPT?

Hello

I added Cyrix-Li-Charge relay to my van's solar system as required to work with the SmartSolar MPPT and VE.BMS.

Now im facing an issue, the MPPT cant get power in the night, when the PV is not giving enough power to keep the MPPT awake.

So i can't see the history from the application during nighttime and the MPPT also cant keep track of the battery charge stage.

Can someone explain why the Cyrix-Li-Charge relay opens when no solar energy is being produced? It would be good If it opens only when the batteries are being overcharged.


Kind regards

MPPT Controllers
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justmurph avatar image justmurph commented ·

Mine does the same, but this behaviour is how the Li Charge is designed to work. The following is in the product datasheet:

  1. The Cyrix-Li-Charge will connect a battery charger with 3 seconds delay:

    • - if the Charge Disconnect output of the VE.Bus BMS is high, and

    • - if it senses 13,7V (resp. 27,4V or 54,8V) or more on its battery charger connection terminal, and

    • - if it senses 2V or more on its battery terminal (the Cyrix will remain open, if not connect to the battery).


So, as when the voltage from the MPPT drops at the end of the day, the LI Charge disconnects. I suppose the idea is that in a system that has run low, the charge source won't be connected until it's able to provide power and not just be a parasitic draw on the system. If you'd rather always have the MPPTs online, you could use a battery protect instead. They use less power when turned on, but more when turned off.


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davidq answered ·

HI, more detail please. If charged the battery would maintain the MPPT 'alive' overnight and also provide load output. How is the Cyrix control input interfaced to your system?

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bathnm avatar image bathnm commented ·

@DavidQ, Maybe take a look at the data sheet. I believe you may have issues with the Li-Charge as when one side drops below 2v it will open. Maybe what you need is the LI-Load, which doesn't do that.

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muhkel avatar image muhkel commented ·

The Cyrix-Li-Charge relay is installed to the + cable between MPPT and the battery.

So when power is not travelling in from the PV side through the MPPT, the Cyrix-Li-Charge relay remains open and MPPT cant get power from battery side aswell.

Without Cyrix-Li-Charge the MPPT would take the power from the battery...

Am i correct? I think i installed it correctly, based on this schematic: https://www.victronenergy.com/upload/documents/1.6KVA-12V-MultiPlus-230-Volt-system-example-4-PIN-VE-Bus-BMS-Lithium-Orion-Tr.pdf

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