48V: WHAT’S ALL THE BUZZ ABOUT?
If you’ve done any research on a camper van conversion you are sure to have come across the grounds (no pun intended) for a 12V DC system and the benefits that come along with it. So why now the push for a 48V DC system? What’s the deal?
48V POWER SYSTEMS
THE LAWS OF ELECTRICITY
There are many laws that have been created by individuals much smarter than the one writing this blog. Faraday’s law, Ohm’s law, and Watts law just to name a few. For the purpose of this conversation we are going to focus on Watts law, which states in its most simplest form.
Watts= Volts X Amps
Great! Wait, what is a watt again? What about a volt? The easiest way to comprehend electricity is to replace it with something more tangible; let’s use water as an example.
In this example, volts will represent water pressure. Surely you know that the water pump in your adventure van will only pump water out of your faucet if there is sufficient water in your tank, right? Think of the available water in your tank as available voltage.
Amps, or amperage, can be thought of as the rate of water flow, or current, moving. If the water flow in the gutter of your driveway when you wash your car were to represent a low current, a high current would be represented as a white water rapid in the Sierras. Ever wonder how a participant in tough mudder could survive the advertised 10,000 volts of electricity running through their body?! This is because while the volts are undoubtedly high, the amperage is set so incredibly low that is not life threatening.
Last but not least, Watts. Watts is a measurement of power. In our example with water, imagine for a second if we set a water wheel in the above scenarios. How much power would the water wheel generate from the water flowing in the gutter? Enough to turn the wheel? Maybe, but not likely. Enough to drive a motor attached to that said wheel? Probably not. How about that same wheel in our white water rapid. Could the wheel drive a motor? Certainly. What about two motors? More than likely!
Isn't this fun to look at?
2. PROS
Now that we have a basic understanding of Watt’s law, let’s talk about the pros.
The biggest pro to a 48V over a 12V system is the power that it is able to produce. This power in turn permits for larger/more efficient compressors, motors, alternators, to be utilized. For example.
A simple 12V Victron power system.
Cruise n Comfort’s DC Air conditioning HD series specficiations
12VDC / 38-55 amps/ 10K BTU
48VDC/ 8-16 amps/ 12K BTU.
Nation’s alternator secondary alternator specifications
12VDC/ 280 amp/ 3,360 Watts.
48VDC /100 amp/ 4,800 Watts.
Nation's 48V 100 amp dual alternator.
You may have perhaps noticed something else in the above specifications, which leads us to pro #2.
The decreased amperage permits the use of smaller diameter wire. Now, some will say this is safer, and some will also say this is less expensive. In regard to the first statement, any power system with incorrectly sized wire, whether it be 12V or 48V, is not a safe system. In other words, if a 12V system is done correctly (with correct size cabling depending on the rated current) then it is just as safe as a 48V system.
In regard to expense; sure, you are saving some money on smaller diameter battery cable and related wiring. However, the price of 48V components are significantly more expensive than the price of 12V components. So realistically while you are saving money on cable, you’re deeper in your wallet overall.
3. CONS
Onto the cons. First off as mentioned above, 48V systems are more expensive overall in comparison to their 12V counterparts.
Secondly, 48V systems are more complex to build and commission than their 12V counterparts. They require special fuses and breakers than a normal 12V system would not require. For example, Victron’s standard mega fuse for 12V systems are rated up to 32VDC. If one of these fuses was set in place in a 48V system, the fuse would fail instantly. While a 48V system nominally is 48V (a 2x4 isn’t a 2x4, but rather a 1.5x3.5) the voltage of 48V systems will typically be anywhere from 51V-55V. This means special fuses that are rated up to 58V must be used for the system to operate correctly.
This leads us to our next con; special parts. Standard 12V fuses, relays, switches, etc. can be commonly found anywhere in the US at a general auto store. The 58V fuses we just talked about? Not so much.
Lastly, the chance of an accidental short and the possible repercussions. The vehicle’s chassis battery and related electronics are all rated for 12V and can withstand small surges of voltage without damage. If a short to ground were to occur with a 48V system, 48V could potentially enter these components, possibly leading to damage or failures.
4. OK OTG, WHAT DO YOU RECCOMMEND?
48V systems are on the cutting edge of technology and advances in lithium power systems. They do have their place and benefits for certain builds depending on the use case. If we were building out a van for a client that only required a Maxx air fan, refrigerator, lights, and a water pump, we would not even entertain the thought or recommend a 48V system for them. If conversely, a client wanted to be off grid with their camper van and run their DC powered air conditioning days on end, then we would absolutely steer them towards a 48V system.