I have a house battery bank with (4) 12v 100ah LifePo4 wired parallel. Everything was working great with the Orion-TR 12/12 30 Non-Isolated DC to DC Charger wired into the Lynx Distributor. I added one 200 Watt Solar Panel and ran it into a Victron Energy SmartSolar 100/30 MPPT Solar Charge Controller and out to the Lynx. Now the 60 amp breaker located near the Chassis (Starter) battery trips. If I disconnect the leads from the solar, the breaker does not trip. Wire sizes are 6awg from the starter (alternator) to the DC/DC Charger, and from the MPPT to the Lynx. What does that breaker protect and why is it tripping when charging from both sources at the same time?
Is the 60 amp breaker between the starter battery and the Orion Tr 12-12/30? That’s where I expect it to be. Otherwise, it sounds like your Orion Tr and MPPT 10/30 are both feeding power back to the starter battery, which may not be intentional.
Could you draw a diagram?
Yes.
As @marcham said, a diagram would be helpful.
Wiring is the first thing I would check. Perhaps your system isn’t wired how you think it is. For example, I have a 2025 RV with a 50 amp circuit coming off the original tongue battery that I have no idea what it’s for. It’s on my list of things to track down.
As I stated in my first reply, it appears that your system is somehow backfeeding to the starter battery. Put a clamp-on ammeter on the cables at the starter battery to see how many amps are going in.
Posting a wire size is good, also posting the length of the wire is better.