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Tesla shares 48V architecture with other automakers

electrek.co

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Re: Tesla shares 48V architecture with other automakers

#61

Post by bluGill »

rnk wrote: post #13
intrepidhero wrote: post #5

Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…

Just to add the basic idea, the amount of power is amps * volts. So to carry the same amount of energy with a higher voltage, you can you use less amps. The amount of amps impacts how big the wires are, lower amps need smaller wires and that means less space for wires but more importantly less weight of the wires. There is a lot of wiring in a car. Tesla claims this could be 1/4 the amount of copper wiring in an arti…

6 volt autos were going out of style in the 1950s. They did last into the 1960s, but they were already rare by then.

Re: Tesla shares 48V architecture with other automakers

#62

Post by bluGill »

bryanlarsen wrote: post #24
intrepidhero wrote: post #5

Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…

In the case of the cybertruck, the windshield wiper motor to drive that massive 4 foot wiper blade is 5hp and would require 300 amps at 12V. That's larger than a starter motor.

Larger in what way? A starter can draw more than 300 amps in some cases. However a starter only needs to run for a few seconds and then get plenty of time to cool off. You can burn out a starter if you crank the engine for too long. By contrast a windshield wipers needs to run for hours when you are driving in the rain, and thus needs to be larger to dissipate all the heat. (starters are also typically series wound DC motors which are also smaller, they work great for starters but not for most other motor applications)

Re: Tesla shares 48V architecture with other automakers

#63

Post by bryanlarsen »

taylodl wrote: post #56
bryanlarsen wrote: post #32

Earlier quoted context omitted.

Computer chips use ~1.5V or so these days. Why go 48V->12V->1.5V when you can go 48V->1.5V directly? If it's more efficient to use an intermediate voltage, you can choose the most efficient intermediate voltage internally rather than using 12V.

Because we already have the 12V infrastructure and part supplies in place. You're disrupting things for no benefit. We've been running split 24V/12V systems for decades now in automotive applications. It's not that big a deal to change that to 48V/12V systems as many European car manufacturers have done.

No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring.

Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.

Re: Tesla shares 48V architecture with other automakers

#64

Post by bluGill »

epx wrote: post #29

It would be great to have 48VDC in homes, for lightning, light appliances, etc. to centralize the whole power factor control in a single big power supply instead of doing it (poorly, or not at all) at every LED bulb.

You would need larger wires to account for the losses at a house scale. Since nothing runs are 48 volts you still have the bad power supply in every LED bulb.

Re: Tesla shares 48V architecture with other automakers

#65

Post by bluGill »

firebat45 wrote: post #28
rnk wrote: post #18

Earlier quoted context omitted.

We humans are all terrible on some level (except my mom, she was a saint), but if you have enormous power, you can help or hurt a lot of people based on your actions. Musk has a lot of power. He must be a terribly lonely person, not knowing if he can trust anyone or they just want something from him.

Nobody knows if they can trust anyone, not just rich people.

True, but it isn't worth a thief's time to steal things from me, so I'm less a target of dishonest people. Not zero target, but not a big target. Rich people because they have money are a larger target. Nobody would seek to marry me for my money - filing for divorce as soon as enough time has past to make it look like that wasn't their goal - a small number of people would do that and they seek out rich people.

Re: Tesla shares 48V architecture with other automakers

#66

Post by pgeorgi »

bryanlarsen wrote: post #63
taylodl wrote: post #56

Earlier quoted context omitted.

Because we already have the 12V infrastructure and part supplies in place. You're disrupting things for no benefit. We've been running split 24V/12V systems for decades now in automotive applications. It's not that big a deal to change that to 48V/12V systems as many European car manufacturers have done.

No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.

I'd fully expect other car makers to move to an exclusive 48V setup at some point. They just do it gradually: For the new model a part is replaced by its next-gen successor that is incompatible anyway? Put it on the 48V bus. Repeat until the 12V system is done away with - or force the issue when there are only a few components left, or downstep the 48V to 12V right in front of them, once that's cheaper than keeping the remaining 12V system.

Re: Tesla shares 48V architecture with other automakers

#67

Post by bryanlarsen »

pgeorgi wrote: post #66
bryanlarsen wrote: post #63

Earlier quoted context omitted.

No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.

I'd fully expect other car makers to move to an exclusive 48V setup at some point. They just do it gradually: For the new model a part is replaced by its next-gen successor that is incompatible anyway? Put it on the 48V bus. Repeat until the 12V system is done away with - or force the issue when there are only a few components left, or downstep the 48V to 12V right in front of them, once that's cheaper than keeping t…

It'd be cheaper to delete the 12V bus entirely and add 48V -> 12V converters in front of legacy components, even if they needed several dozen of those converters.

Re: Tesla shares 48V architecture with other automakers

#68

Post by waterheater »

intrepidhero wrote: post #5

Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…

Compared to ICE vehicles, EVs are expensive and heavy (according to Slate, an F-150 Lightning weighs 35% more than its ICE sibling). Cost and weight reduction are both important factors for any EV maker to optimize.

Why do you assume the 12V bus doesn't drive high-power stuff? Historically, every single electrical component in a car is powered at 12V. Everything. Your alternator outputs 12V to both power your electrical system and charge the 12V battery. Even the starter and ignition system (distributor or coil pack) transforms 12V into the high voltages needed for combustion.

I'm not exactly sure why 48V corresponds to a decrease in "complexity." My guess is that power and data were sent over separate cables, whereas PoE does everything together. That's just a guess, however.

Assuming the same power requirements, a 4x increase in voltage translates to a 4x decrease in current. Looking at [1], a component requiring 8AWG @ 12V can now use 18AWG @ 48V. That's a significant decrease in copper, resulting in cost and weight reductions. A higher voltage is almost always preferred, though the higher electric potential means you need better insulation and safety measures.

Though there's a saying that it's current, not voltage, that kills, high voltage is widely known to be dangerous. For example, consider the US electrical grid, which is actually a 240V system, not 120V. Three wires come to your house from the transformer: -120V, 0V, and 120V. A normal outlet is connected to either -120V and 0V or 0V and 120V, and you can get a 240V outlet by connecting to -120V and 120V. This 120V-by-default setup is much safer than 240V every outlet, like in other parts of the world, and you can still get a higher voltage for high-power appliances (e.g. clothes dryer).

[1] https://en.wikipedia.org/wiki/American_wire_gauge

Re: Tesla shares 48V architecture with other automakers

#69

Post by jabl »

bryanlarsen wrote: post #63
taylodl wrote: post #56

Earlier quoted context omitted.

Because we already have the 12V infrastructure and part supplies in place. You're disrupting things for no benefit. We've been running split 24V/12V systems for decades now in automotive applications. It's not that big a deal to change that to 48V/12V systems as many European car manufacturers have done.

No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.

> I've seen estimates of $1000 in reduced cost due to reduced copper wiring

What about aluminum wiring? Lighter, cheaper, though bulkier than equivalent copper. Aluminum wiring got a bad rep back in the day, but it seems with current electrical aluminum standards it supposedly works pretty well.

Re: Tesla shares 48V architecture with other automakers

#70

Post by bokohut »

candiddevmike wrote: post #45
epx wrote: post #29

It would be great to have 48VDC in homes, for lightning, light appliances, etc. to centralize the whole power factor control in a single big power supply instead of doing it (poorly, or not at all) at every LED bulb.

Replace all power outlets with Ethernet and have everything run over 48V PoE and get network connectivity too

While this sounds great in practice the reality will be far from ideal for the singular reason of security. The cyber issues are compounding at exponential rates as more and more devices that make things "easy" lack even the most basic security protocols and the production targets to generate revenue asap have zero to nil concern around protecting said devices from nefarious actors while in use. When the electrical and data transfer grid become one, as I believe it must for reasons of efficiency, we are certain to witness chaos and losses like never before. What you cannot see matters most! and in time many will pay the ultimate cost for someone else's 'easy'.
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