To Power the Future, Carmakers Flip on 48-Volt Systems • Hacker News Board

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#61

Post by madengr » Sun, Feb 11, 2018, 5:43 PM UTC

uncle_bob wrote: post #39

madengr wrote: post #15

48 VDC will be good for amateur radio and car audio. Specifically the power amplifiers for both.

Noise from high power motors will be the bane of all operators, even when the car just drives by. However the junk yard will soon be a good place to source 48v generators.

I have a Nissan Leaf, but don’t operate mobile with it. The AM reception on its radio is fine, which I’ve heard is a problem in other EVs. Proper EMI mitigation can be done, but these companies may not spend the expense to do it.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#62

Post by Gibbon1 » Sun, Feb 11, 2018, 7:21 PM UTC

mschuster91 wrote: post #41

Gibbon1 wrote: post #12

Earlier quoted context omitted.

> Yet, it's not high enough to require switching to a different electrical wiring safety paradigm. This is the tldr. Also once you ditch lead acid batteries for higher voltage hybrid batteries there no reason to keep using 12VDC. The math bit is that the required wire size is related to the inverse square of the voltage. At the same time reduced current means smaller switches.

> Also once you ditch lead acid batteries for higher voltage hybrid batteries there no reason to keep using 12VDC. Not really. The operating voltages for most of the actual electronic circuits will still be the usual 3V3/5V/12V - and converting from 12V to 5V/3V3 is easier than from 48V.

The switched loads I was thinking of are lights and motors. So 48V headlights, 48v blower motors, 48v door solenoids, etc. All these draw a fair amount of power and thus a lot of current at 12V.

It's not a total win especially for mechanical switches and relays which tend to be rated by their ability to interrupt power. And you do need higher voltage transistors.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#63

Post by mschuster91 » Sun, Feb 11, 2018, 8:30 PM UTC

Gibbon1 wrote: post #62

mschuster91 wrote: post #41

Earlier quoted context omitted.

> Also once you ditch lead acid batteries for higher voltage hybrid batteries there no reason to keep using 12VDC. Not really. The operating voltages for most of the actual electronic circuits will still be the usual 3V3/5V/12V - and converting from 12V to 5V/3V3 is easier than from 48V.

The switched loads I was thinking of are lights and motors. So 48V headlights, 48v blower motors, 48v door solenoids, etc. All these draw a fair amount of power and thus a lot of current at 12V. It's not a total win especially for mechanical switches and relays which tend to be rated by their ability to interrupt power. And you do need higher voltage transistors.

Hmm. Definitely an interesting idea. Downside: manage to e.g. swap a 12V and 48V line and while an 48V component shouldn't be damaged by 12V, a 12V component which does not have a voltage regulator in front will get fried. It's nasty enough with a truck with dual voltage and trailers - a 24V trailer will at least be recognizable as the lights will simply have a dimmer light but a 12V trailer on a 24V truck means hours of swapping every goddamn tiny light bulb. Add a 3rd voltage into the mess and the potential for chaos multiplies...