Use Orion XS 1400 for DC to DC Charging (12v to 24v) and Power Supply (24v to 12v)

DIY
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1

I may be complicating my setup with this concept. That being said, let’s focus on whether it can or cannot be done, rather than what my alternative solutions could/should be.

The new Victron Orion XS 1400 DC to DC charger can input and output at 12v or 24v. In primary use, I would use it to charge the LiFePo4 battery bank in my truck when driving. My house system is 24v based. Most of my DC draws are 24v, though my CPAP machine takes 12v and AC via my household adapter. The draw on 12v is a good deal less, both from the losses due to the AC adapter and leaving the inverter on for 8+ hours at night when camping, so I’d prefer to use DC.

Here’s where the Orion comes in. When driving, I’d like to have the Orion charge the battery bank from the alternator (12v → 24v). When stationary, I’d like to switch it to be a power source drawing from the battery bank (24v → 12v). The Orion is technically capable of handling these two scenarios. I’m trying to think through what would be the best way to wire this up and I’m open to ideas on how to do so. This would avoid the need for a fixed 24v->12v DC converter in addition to the Orion.

To summarize:

  • Driving Mode - open 12v flow from starter battery/alternator to Orion to 24v LiFePo4 when driving, close flow to 12v fuse block
  • Camp Mode - open 24v flow from house battery to Orion to 12v fuse block when at camp, close flow to/from start battery

Questions:

  • Would some combination of switches between the Orion and the starter battery, house battery, and a fuse block work?
  • What about putting Victron Smart BatteryProtects between the Orion and those three items? (advantage here is controlling them remotely)
  • Would relays of some kind work where the connections to each are opened or closed? (I have a Cerbo GX that could perhaps help here)
  • Other ideas?

Thanks for any ideas you all have. Either way, the Orion has already been ordered and will be used for DC to DC charging. I’d just love to get double duty out of it.

2

Could you make it work? Yes.
Should you make it work? I’m leaning toward no.

The complexity that your end result requires just isn’t worth it.

I design my system with a “set it and forget it” goal. It’s not 100% hands off but I do design it such that my wife doesn’t have to worry about how it works. She turns on the light switch and the light comes on.

I read that there is talk of making the Orion XS bidirectional. That right there would solve your problem. But I wouldn’t bet on it coming out soon enough for your need.

3

You should use a battery protect anyway. The Victron Orion XS 1400 is non-isolated which means if there is a fault internally you could see 24V on the 12V side.

4

And a fuse would blow…no need for extra hardware.

5

Battery protects will only work with voltage in the correct direction, i.e. input terminal is higher voltage than output. If they are subject to reverse voltage they can be damaged and will not protect against reverse current flow.