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Tim Chapman avatar image
Tim Chapman asked

Cyrix Li-Charge operation

I have, on a friends boat, a fairly standard Victron LFP set up with a VE Bus BMS controlling a Cyrix Li-Charge for over voltage protection and and Battery Protect for under voltage protection.

My assumption is that under normal conditions the Cyrix relay should always be closed and passing charge current, either from the solar or the engine alternator.

What appears to be happening is that the Cyrix relay is clicking open when the engine is running, even though the voltage on its output terminal is only 14.1V.

Can anyone provide any insight as to why the Cyrix is opening? Am I right in my assumption that it should be closed at all times under normal operation as long as the charge disconnect wire from the BMS is high?

Cyrix Battery Combiner
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justmurph avatar image justmurph commented ·

Tim, is it only opening for a few seconds, then closing again? I'm having this issue with mine. Multiple times per day, while the solar is still pumping out plenty of power, the Li Charge will open, then close again a few seconds later and everything goes back to normal. There has definitely been no over voltage event when this happens. What I haven't been able to determine is whether this is a fault in the Li Charge, or if the BMS has made a mistake and told it to open. I suspect the former.


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davidq answered ·

Tim, can we have a description of how your Cyrix is connected? The Cyrix range have particular jobs - typically a Cyrix Li Ct sits between the alternator/boat battery and the lithium battery. You will see from the data sheet that the Cyrix Li Charge behaves differently to the Li Ct and is used between and charger and a battery.

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Tim Chapman avatar image Tim Chapman commented ·

The Li Charge is connected to the LFP battery bank on the output side and the alternator and solar on the input side. The unit is connected to a VE Bus BMS.

As justmurph above the Cyrix clicks open momentarily several times a day, irrespective of whether the engine is running or not. There is no obvious over-voltage condition to cause the BMS to open it.

On my own boat I use a Battery Connect as the HV disconnect but in this instance we chose the Li-Charge as that is what is recommended by Victron.

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