Hey guys, I have 2 Victron Energy Orion 24/12-Volt 70 amp DC-DC Converters Non-Isolated connected in parallel to supply all my 12 volt DC power to my RV. So far the system has worked very well with no issues at all. I have the 12 volt output adjusted to 13.8 volts DC and it maintains that output level just fine regardless of the amount of load applied. My question is this, for additional redundancy would it be ok to install an AGM 12 volt battery connected in parallel with the Orion’s? This battery would just be there for an additional 12 volt Amp Hour supply and a back up to the Orions should they ever experience a failure. I currently have 3 - 200 AH Lithium Ion Batteries on the 24 Volt side. I’m thinking the 13.8 volt output supply from the converters would keep this battery charged/topped off . Let me know what you guys think or have a similar setup. Thanks!
These converters are not galvanically isolated, so if they fail internally you will see 24V on the 12V system. If that could damage something or cause a fire, you could add a battery protect between the DC-DC converter and the loads for overvoltage detection and protection.
If you want to add a battery, it won’t work like a proper charger. It will just send one voltage. Some AGM batteries need equalization to stop sulfates building up, and you won’t get the fancy charge curve. If you connect it to a low SOC battery, the converter will try to push its full current capacity into the battery, which could overheat the converter or damage the battery. I’m not sure if it’s worth doing anything special. Maybe look at UPS batteries that are mostly at full charge for most of their life.
You also won’t be able to add a battery protect because they are unidirectional. If you lose the 24V/12V converter, the battery will supply the loads until it fails.