To 48V, or not to 48V?

[Dave01a]

What voltage are you using?

Have a 12V system, and considering upgrading. I'm well versed in the electrical side of things. Smaller wire gauge for higher voltage etc. My question pertains to what you are running off of it inside.

In my current setup, I have a number of things running directly off the 12V, and only use the inverter for 3 kitchen appliances when needed. Microwave, Air Fryer, and Toaster. Almost all of my DC equipment has a 12V/24V input option.

To my understanding of what's out there, if I take the step up to 48V, nearly everything will need to be run through an inverter. There are at least a few 48V AC split units, but everything else will need to be via the inverter to 110V, or a buck/boost transformer down to 12/24V depending on amperage requirements.

[Snowy]

Like you said, 48v can have some advantages in high current situations like alternator to battery, battery to A/C, and powering today's 120v appliances. Volta's use of 48v allows for a smaller 2nd alternator and smaller wires from the 2nd alternator to the batteries. As you said, the downside is that most appliances are either 120v AC or 12v DC. Inverters and 48v/12v converters add cost, weight, complication, energy waste, heat, and sometimes noise to your rig.

Someday, perhaps we will get native 48v DC appliances. That will be the time to go 48v IMHO.

[booster]

Originally Posted by Snowy

Like you said, 48v can have some advantages in high current situations like alternator to battery, battery to A/C, and powering today's 120v appliances. Volta's use of 48v allows for a smaller 2nd alternator and smaller wires from the 2nd alternator to the batteries. As you said, the downside is that most appliances are either 120v AC or 12v DC. Inverters and 48v/12v converters add cost, weight, complication, energy waste, heat, and sometimes noise to your rig.

Someday, perhaps we will get native 48v DC appliances. That will be the time to go 48v IMHO.

Most don't worry about 48v DC things to run as it is easiest to just run the 48v for charging and inverting. Plenty of advantages in smaller wiring, etc. Downside is taking a bit more space for the 48 to 12v converter and some other costs due to higher cost items. Particularly good for high rate charging from the alternator, but those advantages seem to be fading now with the much more conservative charge rates for lithium that have been coming out recently. Right now many are saying .2C rate for best life and .4C max, which is way, way less than the initially touted up to 3C range for lithium. These are 12v speeds though and 48v will be different but my guess is that the wattage means more, but I haven't seen any data on that to this point.


48v lithium batteries are also a lot more cells in series, which appears to increase the balancing issues that have been getting a lot more attention lately by many folks, so care is needed with that.

[Dave01a]

Yeah, 48 is doable, but so far, the 24 seems to be the way to go for direct connect devices.

Inverter efficiencies have come way down, but there is still enough loss to justify staying with 24 when you can for small installations. When I get to the diesel pusher conversion, that will probably be 48v, but still on the fence on that one as well.

[avanti]

Yes, when we did ours, it felt like 24V was the current sweet spot (no pun intended). I really like that all the 12v stuff runs on regulated 12V from buck converters, rather than fluctuating according to the charger's whims. I have a big 100A converter that runs all the major stuff, and several little ones for scattered small devices, most of which require USB-C. This is more for wiring convenience than any theoretical reason.

Speaking of USB-C: note that many USB-C converters are spec'd at 12-24VDC, but you often won't get full-current for things like laptop or phone charging unless they are running at 24V.

[Dave01a]

Avanti, do you have the info on that converter? I don't see many results in searches for higher amp converters, always want to expand my database.

I tend to agree with you on the 12/24 units. I do have a USB charger that I really like that is literally 24V max, so I may have to add a 24V regulator into the mix. I have a fanless brick PC and a pair of 20" LED monitors that use 2A each on 12V, so a small buck/boost dedicated to them is in the works regardless of 24 or 48. The AlpiCool units will take a max of 32V, so they should be good and run better on 24 to boot. I have two 32qt I use as fridge and freezer, and a 9qt I made a special lid for to take between the van and the big trucks I'm delivering.

The lid is made from layers of toolbox foam. Keeps my pop and munchies cool but accessible. Had to add the aluminum angle and strap because the little cooler didn't have a shoulder strap for carrying. Have to carry by hand instead of shoulder, but better one handed than two.

Want a good laugh, just did a quick search on vehicle USB chargers, saw a two port that plugs into the ODBII port.

[avanti]

Originally Posted by Dave01a

Avanti, do you have the info on that converter? I don't see many results in searches for higher amp converters, always want to expand my database.

https://www.amazon.com/Victron-Energ.../dp/B0877ZQZSQ

I tend to agree with you on the 12/24 units. I do have a USB charger that I really like that is literally 24V max, so I may have to add a 24V regulator into the mix.

[Dave01a]

Thanks for the link, saved it in my lists

[Boxster1971]

I have lived with a 48V Volta system for over a year now in my 2024 Airstream Interstate 19e. Airstream has joined Winnebago, Storyteller and other major B-van builders switching to 48V lithium battery systems. While it is trendy, I’m not sure that is the best solution currently. I agree with @avanti that 24V is probably best at this time since there are many things that can run on either 12 or 24V.

The Volta battery provides 13.2 kW of power. The system has a large 3.2kW inverter with 6000W Surge rating that provides an equivalent to 30A - AC shore power. It also has twin 30A 48V-12V DC converters that provide 60A of regulated 13.8 volts of stable power. The secondary 51V, 6900W Alternator is the big advantage of this 48V system as it will recharge a depleted battery in a few hours of driving with large 4/0 cables running from the engine mounted alternator to the battery mounted in the rear spare tire space. A 12V alternator system would only provide half that much recharging capacity.

I’m not convince that the Volta system is the best solution and noticed that both Winnebago and Storyteller dropped the Volta battery in favor of Lithionics.

[Dave01a]

The ideal situation would be for all the ancillary items to be available in 48V, but until it becomes more widely used, I just about have to stick with 24 from what I'm reading.

BTW, I grew up when all the big engine vehicles and equipment was 24V, but as far as I can remember, every big truck I've delivered the last two years has been 12V. I guess I should be thankful the 24V systems have been out long enough to keep the 24V accessories still in production as the RV solar market for them gets up to speed.