The Ultimate Prius Battery Mod for 44% better Mileage

No, that's not the case. "Ohm/cm3" is shorthand for "ohms per cubic centimeter". Therefore, as you get more cubic centimeters you get more ohms. One way to read this is each cubic centimeter has "x" ohms in it.

10 cm3 x 1ohm/cm3 = 10 ohm (note that the cm3 in numerator of the first term cancels out the cm3 in the denominator of the second term, leaving you with just ohms).

100 cm3 x 1ohm/cm3 = 100 ohm

If you get 55 miles per gallon in your Prius, and you increase the number of gallons you used to 10 gallons, then you ended up with 550 miles.

10 gallons x 55 m/g = 550 miles

While we're on the subject, what about the claim of 5-10 times greater storage capacity. A battery (by definition) is a device used to store and discharge electrical energy by means of a chemical reaction. In a battery this chemical storage comes in two parts, the electrolyte and electrodes. Once you have used up all of one or the other, there is no more ability to store/discharge energy regardless of how much extra electrolyte (or electrode) you have.

In practice, a battery does not use up all of either it's electrodes or electrolyte during its charge/discharge cycle. So, it is possible to get additional capacity from a battery by causing the root chemical reaction to go further and to a different equilibrium condition. For a moderately complete dissertation on the subject, check out:

Nickel-metal hydride battery - Wikipedia, the free encyclopedia

from that, note the following charge/discharge equation pair:

The negative electrode reaction occurring in a NiMH battery is

The electrode is charged in the right direction of this equation and discharged in the left direction. On the positive electrode, nickel oxyhydroxide (NiOOH) is formed,

Since you can see in both of these equations that the reaction of one nickle complex and/or on metal hydride complex produces one electron, then, in order to get a 5-10 times increase in the storage capacity of the battery, one would need to effectively use 5-10 times more of the nickle/metal hydride contained in the battery. Assuming that the new method somehow uses 100% of the material contained in the battery, then the current battery uses 100/5 = 20% to 100/10 = 10% of the NiMH material in the battery.

So, the claim here is that some lone inventor with bad data has somehow managed to get a 5 to 10-fold increase in the amount of available (useable) nickle/metal hydride in the battery. Even a 5-10% increase in the use of the electrode material would have the major battery companies beating down his door.

Count me a skeptic until you can show me the data.

 

And hoist by my own petard, since I mis-spelled "nickel" as "nickle" and didn't catch it until after the post. Can't seem to edit it, so apologies to all.

 

Bleh!

Reading about the ideas is interesting. What the idea will do to battery performance seems completely unknown at this point.

Why he would go straight to testing the batteries in a Prius instead of doing straight performance tests on a battery is really strange. Really, Really strange.

I am betting the guy is smart, but kind of an oddball inventor type. Not a real scientific type of guy.

 

In an effort to separate the apples from the oranges, let's just
take the car out of the equation entirely. MPG and range of
the Prius has everything to do with how it's driven, NOT with how
capacious or current-capable its batteries are UNLESS you're
talking about charging from an external source to add energy.
In the stock system you're getting all your energy from the
gas and what you do with your foot dictates how well the driver
utilizes the available battery capacity in and out.
.
So now we're reduced to talking about battery efficiency through
this "electrolyte convection" stuff, if I'm not mistaken, which
can be discussed on its own as a topic. Now, let's consider
the structure of the NiMH cell -- interleaved thin plates with
a pourous separator, right? The many holes are presumably to
increase surface area of each electrode. Would I be right in
saying that battery current arises from ion and electron exchange
between the plates? Such that the most benefit would come from
taking the *shortest* possible path through the electrolytic
medium? How, then, would altering the flow path via this
"convection" stuff lower internal resistance when it seems to
me that the object is to LENGTHEN the exchange path??
.
It seems to me that you should get the good Doctor in here to
catch up on this thread and start explaining things directly,
because I'd like to think that the people around here could give
him a good run for his money. [and no, I'm not referring to
efusco here..]
.
But don't base any sort of "proof" on the MPG of a Prius, base
it on data about the *batteries* themselves and only then see
if any provable improvement would be worth HEV utilization.
.
_H*

 

Therein lies the problem in my mind with using the Prius as a testbed. To my knowledge, no amount of battery capacity increase will result in significantly improved mileage in an unmodified Prius. The battery controller just does not allow it to make use of the extra capacity. Cal-cars gets around this by adding capacity and significantly overdriving the voltage to trigger "SOC drift" corrections. The nominal voltage of a cal-cars phev pack is 240V, while the oem pack is nominally 201V. Commercial phev converters mostly replace the battery controller with a custom designed/programmed one. Even once you get past this issue, just increasing capacity and lowering resistivity also doesn't significantly increase mileage. You can clearly see this in any number of the phev conversions around that have much larger capacity and lower resistance batteries than stock. They get great mileage when charged up off the grid, but once the battery is run down they are considered to be doing well if they can make up enough efficiency to offset their 200-300 lbs of added weight (ie 1-2 mpg). This is because ultimately all the power still has to come from the gas engine, whether its driven directly from the generator, or recaptured in slowing down the car.

Reduced resistance will decrease voltage sag under load (which can improve acceleration), but nothing in any of this information has implied that the nominal voltage of the cells has been increased. The test data supplied is consistent with reduced resistance, but does not indicate a change in nominal voltage or necessarily in capacity. To my (admittedly limited) knowledge, battery SOC can not generally be determined accurately by voltage under load. This is in part because a lower resistance battery will have a higher loaded voltage at the same SOC as a higher resistance one under the same load. SOC is normally determined by the resting voltage that the battery returns to after a discharge event. That data is not shown, only the voltage profile of the discharge. This is why most EVs run a "fuel" gauge based on a coulomb counting algorithm. The real time voltage meter is just not a reliable indicator of SOC, even when your batteries are well know. With nimh, its even worse, as even resting voltage is not necessarily a very accurate predictor of SOC. You basically have to charge them up with a peak detecting charger that also counts coulombs and see how much "gas" you have to put back in the "tank" to figure out how much you took out. The large run to run variation in the test data is worrying, and calls the test conditions a validity of the data somewhat into question. Any time your measurement reproducibility is less than or similar to the difference between the article under test and the control you have to be very careful about what you can claim based on the results.

Lastly, google popularity aside, there is a problem with the resistance units. Resistance is a calculated value for a specific geometry of a given material measured in Ohms. Resistivity is a physical property of materials, normally given in Ohm*m or Ohm*cm. Resistance is defined as resistivity, divided by the cross sectional area, and multiplied by lenth. Ohm*m*m/m^2 = ohms. Simplifications are sometimes made for specific cases. Sheet resistance is often given in Ohms per Square for materials of fixed thickness. The actual resistance is the Sheet resistance multiplied be the ratio of Length to Width. For a known cross sectional geometry, such as a piece of wire, resistance is sometimes specified per unit length, in Ohm/m or Ohm/cm. There does seem to be a quantity referred to as "specific resistance" which is the resistance of a 1 cm cube amount of something. The correct units for this quantity would be Ohms, as this truly is the resistance of a specific geometry as mentioned above. The temptation is there to call this Ohms/cm^3 since it is the resistance of a unit cube, but this is not correct. For a quantity to be expressed as per unit volume it must have the same value for any manifestation of that volume. The specific resistance is only valid for a cube 1cm on each side. Any other shape or aspect ratio also having volume of 1cm^3 will result in a different calculated resistance.

Ultimately I'm not really sure what we are trying to accomplish here. If he can convince Toyota that he's on to something, maybe we'll all be driving magnetized phev Prii in a few years. Given all the battery development going on out there, this isn't where I personally would put my money, but what do I know? I guess maybe its time to wish Dr. O'brien the best of luck and move on...

Rob

 

That sounds a lot more reasonable. The units are still wrong in my opinion, but as I suspected it appears this is just a difference between Chemistry speak and Electrical Engineer speak.

Adding more free electrolyte and keeping it stirred up will probably do good things for the battery in terms of resistance and capacity. My main concern would be crash safety. A big part of the reason why the batteries are "dry" is so in the case of an accident you don't have acid or in this case drano (KOH) splashing around the passenger compartment. Other concerns would be effects on battery life, temperature performance, and various other parameters. I had thought that at least in the case of lead batteries, one of the reasons to run somewhat electrolyte starved was to protect and prolong the life of the electrodes. Anyway, as I said before, battery design space is a very complex trade of many performance variables. Its not that hard to optimize one of them to be really impressive, but this is usually at the expense of others. Starter batteries are a good example of this. They are optimized to provide a lot of current for a very short duration. A big trade off is that in general they have very little tolerance for being deeply discharged. They may fail in 10 or even fewer cycles if you attempt to do so. Conversely a deep cycle battery will have generally much lower current/capacity rating for the same size/weight, but is able to be cycled hundreds of times.

At this point there is no real evidence to show whether this is an overall improvement, or just an optimization trade within the same space at the expense of other parameters. To be fair there really hasn't been any data to show an improvement at all, but thats just my interpretation of the initial data. We'll have to wait and see what the data says. Unfortunately in this regard, any data gathered from use in a Prius will in my opinion be highly subjective and not really admissible in a scientific court of law It will be interesting, but highly subject to interpretation.

rob

 

But the Panasonic modules aren't "shipped dry". They come with
their full complement of presumably well-mixed and well-
distributed electrolyte already inside.
.
The measured internal resistance as measured by the ECU is on
the order of a couple of hundredths of an ohm per block, i.e.
12 cells. At fifty or a hundred amps you'll get a little
heating from that, sure, but not a whole lot. You would get
significantly *more* heating by trying to overcharge, since
now all that energy needs someplace else to go.
.
I think we can just stop here.
.
_H*

 

Thanks for the lengthy reply Fibb. It still leaves a lot of questions, but what he says does make more sense that all of the general claims. (5-10 times capacity) Please post any additional data that you receive from your friend. Hobbit may not be interested ("I think we can just stop here.") but others of us are interested.

Clearly, the main thing he is shooting for is a passive way to mix the electrolyte, which will lower the internal resistance of the battery. How a lower internal resistance affects the overall performance of the battery, has not been clearly explained.

Thanks.

 

i never expected the explanation to be complete, but it does very well considering the expert to novice translation issues.

there are a lot of questions imm as well, but i think it be a combination of my ignorance, misconceptions, and his interpretation of our intelligence. the post as long as it was, would have to be much longer to even scratch the surface of what we are dealing with...

also, i would be hesitant to provide too much detail as this is a public forum and revolutionary ideas like these have a tendency to be intercepted and buried if the wrong people get wind of this.

the OP suggests real world trials currently in progress. i guess what we need is someone in the Vancouver area to independently verify the results these changes are causing

Jonathan??? you live in the area dont you?

 

i dont think this is true, you would have to do a huge modification to the management system.

classic prius for the win!

 

lol damn but nice try, at least you now know toyota preferred reliability rather than short term performance.

 

How do you magnetize none ferrous metals? Or are they particles from space?