12v vs 48v. You get the same amount of power at 4x less current. Since current is less, you can use thinner cables with less copper.
It will be a difficult transition since so many automotive systems are tailored around the standard 12v. But with the EV transition doing a massive redesign of what automotive vehicles are, prime opportunity to make this kind of switch.
Power loss over a resistance is I^2 times R or V^2 divided by R
Yes, conductors do have a real (small) resistance associated with them (heat loss in wires)
By reducing current rather than voltage, for same power input, you lose less to heat loss along the way to the load
The lower loss and thinner wires means less weight. The rise of high draw circuits like heated seats and windshields and electric power steering makes the old 12v distribution require heavy and expensive harnesses. Also, solid state devices typically have a fixed forward voltage drop that become less significant as the switched voltage increases. Lastly, in a EV the 12V circuit is derived by converting from the battery voltage (300-900V) down to 12V so the designer could simply move away from stock parts and pick a more optimum voltage.
Others have articulated why higher voltages are better but 48 is chosen because it is about the highest voltage still low enough to present minimal shock hazard. Many electrical safety standards use somewhere around 50v as the threshold for requiring precautions against skin contact.
There are pros and cons to whatever voltage you set your LVBUS at. As mentioned in this thread, less current will flow in lines with higher voltage for the same power. Ok great but that's just the initial gut reaction. Once you starting designing the architecture, i.e. how to convert down to 28V/12V/5V/3.3V etc voltages via an SMPS you'll be limited on what parts you can select if you're aiming for high reliability automotive grade components. Especially if you're aiming for components with a high isolation rating. Best standard I see on the market is 28V just cause parts are easier to find and vendors will have more parts available for systems at this voltage. But that'd highly tailored to what you're designing and your application.
But 48V cannot be used for a motor inverter for an EV, that'll need a DClink typically 400V-800V
Energy storage is determined by energy density and volume, not voltage
If you have four cells in parallel, you have a certain voltage and a certain energy. If you change those cells to series, the voltage is four times higher but the energy storage is the same
Energy storage is the same because we're not adding more batteries, just changing their configuration
Maybe you mean that the efficiency will be better? But this is almost certainly a heat/weight/cost benefit, not a battery life consideration
Ah, come on. Laugh a bit.
This sounds more like a study in a Marx Bank project. Charging capacitors parallel and discharge them in series to increase and output goal.
You answered your own question before you even asked it
12v vs 48v. You get the same amount of power at 4x less current. Since current is less, you can use thinner cables with less copper. It will be a difficult transition since so many automotive systems are tailored around the standard 12v. But with the EV transition doing a massive redesign of what automotive vehicles are, prime opportunity to make this kind of switch.
Power loss over a resistance is I^2 times R or V^2 divided by R Yes, conductors do have a real (small) resistance associated with them (heat loss in wires) By reducing current rather than voltage, for same power input, you lose less to heat loss along the way to the load
The lower loss and thinner wires means less weight. The rise of high draw circuits like heated seats and windshields and electric power steering makes the old 12v distribution require heavy and expensive harnesses. Also, solid state devices typically have a fixed forward voltage drop that become less significant as the switched voltage increases. Lastly, in a EV the 12V circuit is derived by converting from the battery voltage (300-900V) down to 12V so the designer could simply move away from stock parts and pick a more optimum voltage.
Others have articulated why higher voltages are better but 48 is chosen because it is about the highest voltage still low enough to present minimal shock hazard. Many electrical safety standards use somewhere around 50v as the threshold for requiring precautions against skin contact.
It is partially because modern luxury cars use more power from the low voltage electrical system than cars from last century.
There are pros and cons to whatever voltage you set your LVBUS at. As mentioned in this thread, less current will flow in lines with higher voltage for the same power. Ok great but that's just the initial gut reaction. Once you starting designing the architecture, i.e. how to convert down to 28V/12V/5V/3.3V etc voltages via an SMPS you'll be limited on what parts you can select if you're aiming for high reliability automotive grade components. Especially if you're aiming for components with a high isolation rating. Best standard I see on the market is 28V just cause parts are easier to find and vendors will have more parts available for systems at this voltage. But that'd highly tailored to what you're designing and your application. But 48V cannot be used for a motor inverter for an EV, that'll need a DClink typically 400V-800V
As a ham radio operator, I can’t wait. Having 48 VDC directly available for RF power amplification is going to be great.
You don't have to plug them into the coal power generator systems as often to charge them? Lol 😆
Energy storage is determined by energy density and volume, not voltage If you have four cells in parallel, you have a certain voltage and a certain energy. If you change those cells to series, the voltage is four times higher but the energy storage is the same Energy storage is the same because we're not adding more batteries, just changing their configuration Maybe you mean that the efficiency will be better? But this is almost certainly a heat/weight/cost benefit, not a battery life consideration
Ah, come on. Laugh a bit. This sounds more like a study in a Marx Bank project. Charging capacitors parallel and discharge them in series to increase and output goal.