question

I've not done this exact setup but Justin or Matthias probably would know better with your components

My guess from working with both 12 and 24v systems...

(a) as long as you have the same charging profiles (voltages) in the circuit the

(b) the BMS will sort out what it wants (all the amps it can handle).

That said, depending probably more on exactly HOW you have your wiring set up for the 24v and 12v side of things it would be almost negligable on 24v here or 12v there, with the real difference being that 24v running in 12v adequately sized wiring will have FAR LESS voltage loss (and with half the amps in the line too).

I'd be looking at when and where the conversions happened and go 24v for anything longer distance to your batteries if possible if those bits of efficiency are important. And if you had it set up for 12v then no issues on wiring sizes.

Myself, I'd go 24v for everything and convert from "12" to 24v as soon as possible and from 24v to 12v as late as possible esp. if amps are at all important -which it sounds like it is!

The same goes for any solar you have - more efficient for 24v and 36+v PV's -the more volts the better for small systems I'd say simply as any efficiency losses in components is usually going to be far less vs losses in wiring....

Unless of course your dc-dc converters and bucks are

(c) garbage and inefficient and/or

(d) RFI noisy/polluters -and you NEED low RFI (like on an SSB radio on a boat)

But you are up-converting off a high-amp 14+v alternator. I'd convert right there if you can, low in the engine bay area where some air flow can happen and stay 24v until you need 12v (or 5v) sockets! Then your RFI will be negligable probably and that means you just need good bucks for the down voltage parts with maybe an up line On-Off for when they ae not in use.

That's my opinion. I had 24 for decades and it's more efficient than 12 almost in every situation unless you really need a lot of 12v items all the time spread out and REALLY need low RFI pollution...

The biggest thing you could compare is what you are using off the alternator and it's quality vs another one. That's where micro heat, losses and efficiency could be tested between components and brands IMHO.

If you REALLY want to be cool, you could probably source a 28.8v alternator and START out at 24v and ONLY convert down where needed for your starter motor (and get it rewired to do 24v too)! A 28v alternator would be FAR more efficient than the usual 14v ones!

Then it would only be a situation of how much 12v you actually NEED -you can get 24v LED auto lights for every mobile need so then it's only about your radio and say, laptop dc chargers or portable battery packs that can't handle above 18-19V, and such.. And you could just have a few 12v sockets where you need with a buck behind on a switch for ONLY when you MUST have 12v!

Why not?

24v starters and alternators are not uncommon nor that different in price and having a completely 24v system would be actually safer long-term than using bucks (which is why they don't use bucks in aircraft where failure is not an option).

ONE of the coolest features of Victron gear is that most can go from 12v to 24v systems without needing upgrades! Obviously 12v chargers and such would need to be changed but with some careful planning you can start 12v and upgrade to 24v without needing anything major except your direct chargers (and maybe by now most will also do both)! That's A MAJOR PLUS in my book.

So when your alternator or starter needs replacing, get a 28v one and start out with least losses possible (or get your current ones rewired or exchanged at a rebuild shop)!