Response from Patrick of the Electric Duo on Battery size, facts shared during the Ford meeting, and his deductions from the data shared.

[chl]

DC to DC fails? Yeah....maybe SOL. But if we make some assumptions from how Tesla does it for the CyberTruck....you can jump it with a 12v jump box or other 12v based vehicle with regular jumper cables. It boosts the 12v to 48V internally so the 48v electronics can run. But if the DC to DC is already fried....then you couldn't even get as far as jumping it at all. Right? I suppose I have the same questions you do......

Hopefully, Ford thought about that and has a solution, lol.

I guess it depends on whether the same DC-DC converters are used for whatever jump facility they provide...however...

If you step up the voltage from 12v to 48v, the current output steps down, unless you have a boot converter which will regulate the output voltage and current, but will draw more current from the source as needed.

The limit is how much power the jump source can supply (I x E)... and for how long.

A car 12v battery has a CCA rating (Cold Cranking Amps), which is a measure of how much current it can supply in a short period of time to crank a gasoline engine at 0 degrees F: 30 seconds at 0F temp and stay above 7.2V.

If you are jumping from a running ICE vehicle with an alternator, the limit is the rating of the alternator plus what ever current the battery can supply should the alternator limit be exceeded.

Most passenger car alternators can supply something like 50 to 150 amps (according to a search), which peaks when revving the engine. So that is the continuous amperage a typical car can supply when jumping another vehicle, and apparently real world testing says that is what is typically used when jumping a vehicle.

So how many amps would the Fathom require to boot up the systems with a jump?
We don't know.

F-150 Lightning jump start:

 

[Snakebitten]

I can't imagine it taking a high amperage to "boot up" the Fathom. (or any typical EV)

At least not relative to the current required to turn over a crankshaft.

You just need enough current to fire up "compute", and thus close the HV contacts, allowing for the DC/DC converter to become functional.

 

[chl]

I can't imagine it taking a high amperage to "boot up" the Fathom. (or any typical EV)

At least not relative to the current required to turn over a crankshaft.

You just need enough current to fire up "compute", and thus close the HV contacts, allowing for the DC/DC converter to become functional.

Yes, I hear ya.

Most of the Fathom's systems are on 48V, powered by the HVB via a DC-DC converter stepping it down from 400V.

The 12v system is likely derived from the 48V.

So, come to think of it, what would the purpose of a jump even be in the Fathom?

If you've lost the 12v system in the Fathom, it is not due to a weak or failed 12v battery - it would be the DC-DC converter or some component up the line powering it.

Just jumping the computer back on will not solve that problem.

So no point in jump terminals it seems to me.

 

[Snakebitten]

We don't know how many components in the Fathom are actually 48V.

Someday, perhaps nothing in the electronics side will be 12V, but it's a tall order to get every low voltage component being acquired from the external automotive industry suppliers to convert.

48V has been utilized in the commercial computer space for a long time now. POE has had a 48V platform for decades. VOIP hardware has been from the beginning, allowing for enough current to be carried on tiny ethernet conductors.

It's coming. Just don't know yet how much of the UEV is already built for 48V

 

[onuiebvbevnulib]

Here are some of the 48V components available today:

48V automotive components are widely available today across major manufacturers like TE Connectivity, Molex, Texas Instruments, and Aptiv, spanning powertrain, safety, and comfort systems.

Core 48V Power and Conversion Components

• DC/DC Converters: Step down or bridge 48V to traditional 12V rails and high-voltage systems for software-defined vehicles.
• Smart eFuses & Switches: High-side switches and integrated current-sense amplifiers offering short-circuit and reverse-current protection from Texas Instruments.
• Batteries : 48V lithium-ion battery pack

Electric Drivetrain & HV Battery

• Pumps: 48V electric coolant pumps

Chassis, Body, and Safety

• Steering & Braking: Steering-by-wire, active roll stabilization, anti-lock braking systems, and integrated power brake boosters (like Bosch iBooster).
• Cabin Comfort & Thermal: windscreen heaters, auxiliary cabin heaters, and high-wattage seat heating. Cabin climate control fans.
• Window lift motors

Connectors and Architecture

• Sealed Connectors: Ruggedized mid-voltage connector families from Molex (MX150), TE Connectivity (LVCS series), and Aptiv engineered to handle up to 60V while reducing overall copper harness weight by up to 75%.

From the Cybertruck design I really hope to see these in the Fathom:

48V Components and Systems

• Steer-by-Wire Motors: Large motors driving the steer-by-wire system operate at 48 volts, requiring a quarter of the current of a 12V setup and allowing smaller control switches.
• Cooling and Thermal: Radiator fans and cooling fans run directly on 48 volts to handle high thermal loads efficiently. Coolant pumps.
• Power Steering: Powered by multi-motor actuator setups running on the 48V bus, backed by redundant power sources.
• Body Electronics: Window lift motors (redesigned by suppliers like Brose), doors, exterior/interior lighting, and the touchscreen interface.
• Pumps and Accessories: Air suspension pumps and dedicated 48V power accessory feeds located in the truck bed and frunk.

Key Benefits

• Reduced Copper and Weight: Higher voltage reduces current by four times, allowing much thinner wires that decrease overall copper use by roughly 70%.
• Power and Data Integration: Gigabit Ethernet wiring daisy-chains components, sending 48V DC power and high-speed control data over single lines.
• Redundancy: Dual DC-to-DC converters (Power Conversion System 2) supply independent 48V feeds as a fail-safe for critical safety components like steering.

The redundant Dual DC-to-DC converters (48V feeds) for critical safety components should be a must.