[libre-riscv-dev] travelling

[Jacob Lifshay]

On Tue, Oct 29, 2019, 16:03 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
wrote:

> On Tuesday, October 29, 2019, Jacob Lifshay <programmerjake at gmail.com>
> wrote:
>
> > On Mon, Oct 28, 2019, 22:08 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
> > wrote:
> >
> > > Apologies I am currently travelling and also getting set up to go to
> > Costa
> > > Rica to meet TEC University, there are a couple other really critical
> eco
> > > conscious projects other that the processor and the EOMA68 one that
> need
> > to
> > > get kicked into high gear.
> > >
> >
> > No problem. just don't fall for the trap of doing too many things to do
> any
> > of them effectively. :)
>
>
> Got really nice team this time. Been planning for about 12 years.
>
>
>
> >
> > Safe travels.
> >
> > These involve transportation: both the vehicles themselves, as well as
> the
> > > powertrain.  I am presently working hard to do the CAD Model on a
> > variable
> > > compression ratio multifuel SIMPLE and libre engine with extremely high
> > > efficiency, as well as kickstart an ebike conversion project that will
> > > dovetail into a "mobile battery and distributed internet franchise".
> > >
> >
> > Neat!
>
>
> And (surpriise) the processor will end up in the lithium battery packs, and
> so will an EOMA68 Card
>
>
> > The multifuel engine is intended for a TRIBRID drivetrain, involving
> > > electrolysis during braking instead of damaging batteries (yes, regen
> > > damages batteries) then injecting the mixed hydrogen and oxygen into
> the
> > > engine.
> > >
> >
> > I think you may run into issues with needing a massive electrolysis cell
> to
> > absorb the full braking power, since electrolysis needs low current/area
> in
> > order to not waste a lot of power on overpotential or damage the
> > electrodes.
>
>
> Correct! Bill Ross is the inventor of exactly that. He uses Potassium
> Hydroxide as a catalyst, and nickel plates with 0.004 in clearance, 2.5v @
> 50 A and you get enough hydrogen to add to a family sized car.
>

I don't think that's nearly enough power (unless your using a whole bunch
of those cells in series and parallel): if a car slows down at the same
rate at which it accelerates, then the braking system has to absorb as much
energy as is produced when it accelerates: for a puny 10hp engine that's
about 7.5kW -- much more than the 125W absorbed by 2.5V 50A. a decent car
would have to deal with 5 to 20 times more power than even the 7.5kW
(though mechanical brakes can deal with dissipating the extra power --
those are needed for backup anyway).

braking from 100km/h to 99km/h in a 1000kg car in 1s produces an average
power of 7.677kW. most people brake much faster than that.

>
>
> > You may want to check out using supercapacitors instead, as a temporary
> > energy storage mechanism,
>
>
> No, because the voltage varies with current, naking it extremely difficult,
> electronically, to deliver the power back.
>

that's not that hard to deal with, all you need is a high-power
bidirectional buck-boost switching regulator and a controller to manage
which voltage the caps should be at.
here's a lower power design i found on google (about 1kW):
https://pdfs.semanticscholar.org/c8ce/2e345a70c23cd722770bb182cb49cc886b4f.pdf

by using some decent SiC mosfets or igbts and good passive components you
should be able to handle a few hundred A at 200-300V, which is sufficient.

one of the problems you would have with supercapacitors is the cost of the
capacitors, though.

>
> What the supercapacitors *are* good for is fronting on the batteey packs,
> directly at the controller.
>
> The decreased resistance results in power being first delivered *from the
> capacitor* which protects the battery from high load.
>

they are not used very effectively there due to not being able to
charge/discharge very much due to the relatively fixed battery voltage.

>
>
> > since they have a very high power rating (in the
> > range of 1000x batteries) due to not being based on a chemical reaction.
> > additionally, supercapacitors don't need additional plumbing and don't
> need
> > water refills. they also can skip the big energy loss of
> > internal-combustion engines which are usually less than 50% efficient.
>
>
> Funny you should mention that. Google 6 stroke engine wikipedia
>
> https://www.youtube.com/watch?v=IovhYvKpFRQ
>
> Patents from 1880 and 1921 show that water flashing to steam when injected
> at TDC will not only cool the cylinder but will actually do "work".
>

neat!

My personal favorite is the sterling engine, which in a hybrid car can
overcome it's disadvantage of needing a long time to start due to being
able to operate from the batteries while the engine is warming up.
additionally, it's much quieter due to not discharging the cylinders to the
exhaust.

>
> As efficiency is a direct product of temperature differentials, the 2 extra
> strokes can result in a whopping FORTY PERCENT efficiency improvement.