What is the difference in 12V and 48V? One of the first questions you may be wondering once you get serious about solar or off-grid living is what size battery do I need? Without getting too technical, let’s jump in and figure it out.
One of the first things you need to know is
What are Volts and Amps and Why Do They Matter?
A Volt is a unit of electricity that measures the potential between amps and resistance. Consider amps your energy and volts the push to get your energy out. With small volts you have a large amount of energy with little push. So you need more amps flowing (and heating up your equipment) to get energy. With high volts however, you need much less amps to get the same energy due to the “high push”. Much more efficient and equipment-friendly.
What you need to know is that the Lower the Volts the Higher the Amps. You (and your equipment) Do Not want high amps. Besides being hard on your equipment, high amps increases your build cost due to the expensive and hard-to-work with materials needed to handle the high load.
When Do You Need a 12V VS 48V?
Small systems that only need a few hours of usage are great for 12V. Now a days though, with so many people creating and taking control of their own power for living, we are seeing a need for larger systems.
To keep it simple:
If you need to run a refrigerator or AC Unit (or other high draw items), you need a 48V.
If 48V is best, Why are so many in the Vanlife and RV Community Building Systems with 12V Battery Banks?
- Van/RV Appliances are 12V So People Assume They Need 12V Batteries.
Even if you have appliances that run on 12V, if you have a lot of them you have a large system. If you have a large system 48V will be more efficient and cost effective. All you need is a DC to DC converter (see more on this below).
- They Think Small Setups Don’t Need Large Batteries
If you only need to run a few lights, a small fan, or very small appliances for a brief amount of time a 12V Battery will work nicely. If you need to run a refrigerator or AC, or stay off-grid for more than a few weekends a year, you will do much better with a 48V System. (Lit Batteries are made for serious off-grid use and have helped people across America boondock for years at a time…on ONE battery!)
- Social Media/Influencers Highlighting 12V drop-in-replacements
When getting inspiration from Facebook or Instagram, many people are finding multiple 12V Batteries configured in series or parallel. This was started from the need to replace lead acid batteries with Lithium Ion batteries. Since many people are unaware that using 3 or more 12V batteries together causes loss of efficiency and limited potential to grow we see these 12V setups that are unnecessarily expensive, complicated, and easily unbalanced.
- RVs Come With A 12V Battery and Adding More 12V Seems Simpler Than Adding 48V (Tip: It’s Not)
To add multiple 12V Batteries you will need to understand what configuration to run them (series or parallel) plus more materials, equipment, and more time to install. When adding a 48v Battery to your 12V system, all you need is a DC to DC converter. The DC to DC unit will run your 12v loads through your 48V Battery and can even be setup to charge your existing 12v battery.
12V VS 48V In a Solar Scenario
When you see the batteries in a system with the numbers laid out, it is much easier to see the effect of higher volts vs lower volts.
In the 12V VS 48V infographic above you can see how a 48V offers 4X the potential than a 12V system. Let’s break it down a little more
A 4.8KWH System will run a Van, RV, or off-grid Cabin with an AC and other typical small appliances. So let’s see the difference it makes with the different key factors highlighted like the battery bank, the Amp draw from Inverter, and the watts allowed into Solar Charge Controller.
The Battery Banks 12V Vs 48V
If we wanted to build our 4.8KWH Solar Setup with 12V Batteries at 100AH we would need 4 batteries hooked up in parallel (keeps it 12V and adds the AHs together providing a large amount of energy, which we saw from the first Volts and Amps infographic above isn’t efficient or good for equipment). Or we can use One 5.5KWH Lit Battery at 48V.
Amp Draw From Inverter 12V VS 48V
On this large of a system we would use a 3000W Inverter. The focus here is the Amp Draw from the Battery Bank and the Goal is to Keep The Amps Low. A 12V draw on a 3000W Inverter would be 276 Amps. With the surge allowance peaking at 2X and even 3X your numbers could soar to 552 – 828 Amps. This is where unnecessary expensive wiring and equipment would be needed.
With a 48V draw on the same 3000W Inverter you would get a continuous Amp draw of 69A, peaking on surges at 138 – 207 Amps. As you can see, 48V is much more manageable and cost effective.
Watts Allowed Into Solar Charge Controller 12V VS 48V
If you are running a large system with 12V batteries, you may need 2 or even 3+ solar charge controllers(SCC). If we went with one Victron MPPT 150/35 SCC for our 4.8KWH system you would only be able to get 500W from your solar panels. This would help keep your batteries charged but would not be sustaining. You would either need multiple SCC’s, (or one massive, expensive SCC paired with high output wires and equipment) or an outside charging source such as a generator.
With 48V you would get 2000W from one Victron MPPT 150/35 SCC and that would be enough to sustain your Battery Bank full time.
In Short,
48V is King
You will not only save money and have a more powerful system by going 48V, but you will have an easier build, less materials, equipment, and a system with unlimited potential to grow. If you are trying to build an off-grid solar system and wondering if 12V or 48V would work best for you, just remember…
12V Is Made To Power A Car, 48V Will Power Your Life.
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