You don't know that. The real point is, it would create a consistent imbalance in the cell usage as well as greatly complicate the wiring in the car, running power from two different sources. The main battery runs the motor and a converter to provide power to keep the 12V system working. Then the entire rest of the car runs off that.
Years ago, there was a big push to up the standard voltage on cars to 48 or 56 volts (don't recall the exact number). It never happened.
You need to be within sight of the box or you end up solving a problem you don't have.
On a sunny day (Thu, 1 Sep 2022 04:24:43 -0700 (PDT)) it happened Ricky snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:
You still do not see the high voltage issue In a hot water heater the load is purely resistive and all electricity is converted to heat the water no matter how high the voltage, but the power line losses are bigger at 120 V than at 480 V or 230 V as we have here.
Sorry, you have lost me on this one. The power line losses depend on the wiring as well as the current. That's why we run water heaters on 240V. Actually, the line loss is a limiting factor, not something that we try to minimize. It's always low enough that there's little economic reason to worry about the losses. But the wires heat up and can cause problems. So we set a limit and use an appropriate size wire. At higher voltages smaller wire could be used, but it has reached the point of "who cares".
That's what it has in common with running a BEV motor off 400V batteries. It's a level of performance called, "good enough". No point in trying to guild the lily. The focus is on extending range in significant ways. Turning the charging world on its head is good enough reason to stick with 400V.
Yes, and I'm sure there are many ways to provide microscopic improvements in efficiency. This is not one any carmaker will use. Maybe in India, because it also is cheaper... maybe. Wiring is not a one time issue. You have to pay to drive it around. It may not be a lot, but neither is the efficiency improvements from tapping the batteries directly, and they will require a lot of extra work elsewhere. It's one of those things that sound good on paper.
On a sunny day (Thu, 1 Sep 2022 16:14:11 -0700 (PDT)) it happened Ricky snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:
Sure,depends on the wire diameter, many things from China come with a 110 V to 230 V spec, and some extra adaptor to US mains sockets... So for same wire dimensions more losses when at 110 V. The water heater is a bit different case.
Just learned a new expression, according to the all-knowing (?) google it is spelled "gild the lily' but anyways, got the point.
Well, as (IIRC) the article mentioned, more cars charging at the same spot makes things a bit easier with lower currents..
I do think very high voltages have their own problem, 800 V and moisture (for example rain) at a charging point needs special safety measures to prevent fire and electrocution... Inductive chargers that you just park above? May melt things too at high power.
There is still work on hydrogen cars gong on, but Hindenburg comes to mind. My idea of every car an RTG would work, but DIY tinkerers would drill holes in those not even mentioning collisions.
That leaves wind powered cars !!! After all Columbus went all the way to 'merrica with wind power!
On a sunny day (Thu, 1 Sep 2022 16:17:38 -0700 (PDT)) it happened Ricky snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:
I dunno take headlights Normal car headlights do not run on a stabilized power supply.
Spread those over a few cells, use 12 V headlights over 3 or 4 cells (whatever battery chemistry is used) Power MOSFETs and optocouplers can switch on individual cell groups. That is already some power, heating or airco maybe an other one. All those switcher losses gone. Sell as super-green!!
Did Ricky actually suggest that resistive heaters are more efficient at higher voltages? Like the 800 volt motors? Would three phase 480 volts be three times as efficient? Hilarious.
In a 100 kW/400 V charging station, the current is 250 A. Assuming 6 A/mm**2 to keep the charging cable reasonable cold, two 80 mm**2 (10 mm diameter) conductors are required. At 800 V only two 40 mm**2 conductors are needed and thus easier to handle.
Why not ho to 1500 V, still remaining within IEC Low Voltage and EU Low Voltage Directive (LVD) with only 5 mm conductor diameters.
Even faster (200-500 kW) charging stations would be available for busses and trucks.
Why not two (or more) 400V cables? It's doesn't take much time to plug and unplug multiple cables. 400V shock is painful. 800V could be deadly. I touched live 400V wires many times. Sometimes i can feel it, sometimes not.
On a sunny day (Sat, 03 Sep 2022 17:11:44 +0300) it happened snipped-for-privacy@downunder.com wrote in snipped-for-privacy@4ax.com:
Using high voltages has its drawback... Here, due to a fire in a HV transformer, the main EHV cables overheatsd and some fell on the train railway That caused a whole lot of infrasructure to be exposed to that EHV, causing fires all along the train track (guess its their control systems). in Dutch, but see the pictures:
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It not so much the voltage but the power behind it that does the harm. Been zapped many times by 25 kV from CRT color sets. But 230 V with some amps will kill you. Rain at a charging station, things like that
A large proportion of California homes use gas for water heating. When electric power is used 240V is generally used. 480V wouldn't give any measurable improvement assuming the usual rules for sizing the wiring.
As of 2023 it will be a requirement to use a heat-pump water heater. They can give about a three times improvement in efficiency.
Yeah, you still aren't grasping that no one cares about the small wire losses. NO ONE CARES because it is not significant in the scheme of operation.
Not sure what you are saying with that.
You don't think they can manage that? From what I've read, they are very efficient, more so than the cable it replaces, in fact.
Hydrogen has its problems, but I haven't heard any references to Hindenburg until now.
It has been proven that a wind powered car can sail upwind, so the world is your oyster it would seem. As long as you have wind. So you many need very tall cars.
On Thursday, 1 September 2022 at 04:30:11 UTC-7, Ricky wrote: ...
The HVAC system runs directly off the tract battery.
...
It was actually 42V (3 x 14v - the 12V system is actually about 14v) that was being promoted 15 years ago or so.
Some current cars do use 48V for relatively high power components such as active suspension, air conditioning and stop-start systems but as you say it is not at all as pervasive as being hyped.
I'm talking about the work required to keep the cells balanced. This is a bad idea, unless you want to add switches to move the loads around the battery pack. Very much overkill. Much easier to just use a down converter. In fact, having a good 12V system is so important, they add a 12V battery.
Perhaps if you learned to read you would understand the sarcasm.
But Larkin was injured by something I said a long time ago, and has been looking for a dig ever since. He has a good grasp of some parts of electronics, but otherwise is a very immature and little person.
The Tesla semi and other electric big rigs will need much larger power level. They may well be a much higher voltage, except I believe they are using the same motors as the model 3. So probably they will just use multiple cables. I believe that's what they do now. Someone showed a picture of an "octopus" cable for the Tesla semi.
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