I have lithium batteries with built in BMSes (Lynac Lithium, 440Ah at 12V) that do not have an external logic signal to prevent over-charging. I would like to connect my Cyrix-Li-ct to permit charging from the engine alternator/starter battery when the engine is running, without overcharging.
What should I use as the input control signal to the Cyrix? I have a SmartShunt, Cerbo GX, MultiPlus, and SmartSolar - but it is not clear to me which of these can be used to gate the connection for both a) engine running (I guess this would be that the vehicle battery >14V) AND b) the lithiums are not already charged (I guess this would be something like lithium battery <14V?)
Or is there another easy way to do this?
Thanks in advance,
greg