A step down converter, 48V>12V can be used to run DC loads efficiently.Haven't watched the video, so don't know the specifics of his thinking, but personally, I think there is a lot of value in 24v as an option. I think of it as the most versatile voltage for a medium sized system, especially in a vehicle. I think for a large system with few or no DC loads, 48V is usually the obvious choice, and for a smallish system with many/mostly DC loads 12V is usually the obvious choice, especially if there is already a 12V system (such as a vehicel build). But for anyone that falls between these two clear cases, 24V can be a good compromise that blends advantages (and disadvantages) of both.
Definitely, a good one and you are only looking at a few % loss. For a larger system or even a medium large system I think of 48V as the obvious choice.A step down converter, 48V>12V can be used to run DC loads efficiently.
Yes, can use a converter for that. Very easy to do. Can use 48V>24V converter.Quite a few key appliances like fridges are available as 12/24V and 24V is just 2x12V batteries in series. Lots of people are only up for 2 batteries, 4 is a huge step
When using an inverter for short high power bursts like a microwave or kettle 24V makes a lot of sense
I took it down because those pages got the least amount of traffic. I think having so many options on the site can paralyze decision making. And personally, I hate when I have to build 24V. I just don't see the point. 48V is better.But I do believe we have gone off topic (sorry OP, I started it) the original question was:
Yes very true! All good points.Definitely, a good one and you are only looking at a few % loss. For a larger system or even a medium large system I think of 48V as the obvious choice.
My personal opinion is there is a middle ground where 24V is a comfy fit for a certain size system, where the upside of moving from 24 to 48 is not that substantial, and other factors might give 24V the edge in some contexts. One of these factors is product availability, anecdotally it seems like its not uncommon to encounter mobile and marine stuff that is hard to find in 48V and on the flip side its not uncommon to see products intended for residential/fixed structures only available in 48V. One example would be alternator charging, DC-DC converters are readily available in 12-12, and 12-24, but if you want alternator charging with a 48V battery I think you are limited to a single brand.
While you usually can find most things for the voltage you choose if you look hard enough and are flexible on make/model, I think 24V has the advantage of pretty decent availability in both mobile/marine market and traditional fixed structures, and additionally many appliances and electronics are 12/24.
Another consideration is PV array configuration, there are situations where moving away from 12V would save considerable cost on the SCC but moving all the way to an array sized optimally for 48V may not be feasible or optimal. For instance, Victron, Epever, recommend an array voltage of roughly 2x-3x of the battery bank voltage (i.e. 2 x 72 cell panels in series for a 24V battery). For a medium sized array, a certain number of panels, or someone that prefers a mostly parallel configuration, configuring the array for 48V battery bank could be difficult.
I do go back and forth though, sometimes I think 24V makes the most sense for a medium to medium-large vehicle based system or boat, but at the same time I can see why someone would choose to stick to 12V even with the sometimes substantially higher upfront cost and/or limitation in system size.
The way I think about it is its all about tradeoffs and finding the optimal solution for your specific use case. I'm not necessarily disagreeing with you or anyone else, its a somewhat subjective topic, this is just me thinking out loud on a topic I like to muse (and split hairs ...) about, and I've always felt 24V was kind of a sweet spot for a certain size+use case.
2 batteries is much easier to place than finding room for 4 batteries. One of the biggest reasons I went to a 24v system in my cabin was the physics. I can only physically fit 6 batteries in the space, so I had the option of going with 6 batteries or 4 batteries and wasted space. The 24v system let me get more watt-hours in the space I physically had.What advantage does a 24V system have over a 48V system when you still need to use a converter?
Can use 2X 24V batteries. Very easy to find. Even Battleborn sells them.
2X 24V batteries fit and provide 48V. I avoid using 12V packs in series when I can. Having 4X bms in a string seems illogical. The less parts, the better.2 batteries is much easier to place than finding room for 4 batteries. One of the biggest reasons I went to a 24v system in my cabin was the physics. I can only physically fit 6 batteries in the space, so I had the option of going with 6 batteries or 4 batteries and wasted space. The 24v system let me get more watt-hours in the space I physically had.
I also find that the 3Kw system is the sweet spot for quite a few applications and the batteries really take up space quick, especially when your environment doesn't allow the use of LiFe batteries (like where it's below freezing for a few months and unattended). Mainly it's the sweet spot for space/watt needed.
I ended up going with the Growatt 3000 setup on 24v. 12v got stupid with the wiring sizes and that allowed me 180Ah of battery over 60Ah if I had gone to a 48v setup.
But not everyone can afford them. Some of us here would LIKE steak, but our wallet says hamburger and WallyWorld 120a FLA's at $100 out the door are just that. Plus you can get FLA's and even reasonably AGM's within a few hours drive but LiFe's aren't in stock anywhere I've been able to drive to. LiFe's may be the greatest thing since sliced bread, but they're not always the best option.
Tl;Dr: @Will Prowse : Please give us the 24v plans back. Pretty please?
I'll be looking forward to it. Its a topic people are interested in, and hungry to understand.Yes very true! All good points.
I think I'll just have to make a video where I run through my reasoning. A big factor is cost. Actually, a massive factor. 48V is cheaper than anything else currently. And easy to find parts for it.
For those using 100W panels, on a flat roof RV, 24V is far simpler than 48V… is it just too difficult to get the panels to output 48V reliably. Sure, placing higher wattage or higher voltage panels would remedy it, but the VAST majority of 100W panels are 17VMP… and in series would have a ton of shading on an rv roof… very difficult to get them outputting 65V…2X 24V batteries fit and provide 48V. I avoid using 12V packs in series when I can. Having 4X bms in a string seems illogical. The less parts, the better.
Ohhh you're using FLA's?? Ok I understand. If you are constrained to that battery box size and voltage, I get it. That's unfortunate.
Ok I'll put them back up.