For sailboat, I plan to use common set up: engine-driven alternator to charge AGM starter battery and use Orion XS to charge Li-Ion house bank. 80-Amp alternator cannot deliver 50-Amps over long period without overheating. Would like to find way to adjust Orion XS charging power based on alternator temperature.
Otherwise, what happens in this scenario? If I use external regulator to control alternator output based on alternator temperature. Set Orion to 40 Amps output. Alternator gets hot, power output drops to 20 Amps, Orion still tries to put 40 Amps into house bank. Does Orion discharge starter battery until low voltage shuts it down? Then alternator charges starter battery, repeats…
The manual describes what happens if the starter battery drops to the shutdown voltage set in engine shutdown settings. The Orion reduces the current to maintain the starter battery at the shutdown voltage, so if only 20A is coming in from the alternator, 1A tail current through the starter battery, the Orion will back down to 19A. So an external regulator on the alternator will work OK.
The only way a temperature controller may work to reduce the Orion output is if you have a GX device, use Node-RED and if the Orion XS control node allows you to reduce the max charge current. You would need to do some research on that.
Thanks for your comments. I understand that the Orion will curtail charging at the shutdown voltage. My concern is system stability. Once the Orion switches off, the alternator - even at reduced output, will quickly boost the voltage of the starter battery and the Orion will switch on again, pulling the voltage down again. Not sure that this cycling behavior is good for long-term. The ability to drop Orion charging output from 40 Amps to 20 Amps would provide better stability.
I had seen reference to Node-RED in other posts. I will look into it. That may be beyond my capabilities to write / implement custom coded control strategies.
Set your shutdown voltage at say 12.9V, just above fully charged voltage, if the alternator rrops below that it is almost completed turned off.