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Battery tech

Hello all.

Just read from autobloggreen about some new battery manufacturer called "Planar Energy". (

They seem to have tech for pretty good Wh/kg batteries. From one of their pdf (

"One of them combines lithium manganese oxide with other ions, and operates at about three to five volts with a charge capacity of 200 milliamp hours per gram."

Calculating that as 3.5V * 200mAh/g you get 700mWh/g or 700Wh/kg. to put that in right context: Roadster battery: 450kg. Drop 30% off as supporting structure: 315kg battery * 700 = 220.500kWh battery. Nearly four times as much as current tech is. That would allow roadster to go 200 * 4 = 800 miles with one charge.

Take a look in the Model S Manufacturing blog Bubba2000, a lot of that information can be found there.

Here's some new tech that looks like it will find its first application in batteries:

Essentially, yarn made out of nanotubes can carry up to about 100X its own weight in superconducting powders, etc. So it could be used for electrodes, more easily than sintered powders now being developed and used for anodes etc.

we are undergraduate electrical engg students we are trying to make a low cost solar car(4 persons carrying capcity) for public transport.
we are having trouble choosing the right battery for our car (4hp powered by hub motors)

can u tell us which is the most energy effient economical battery that is available in the market.

Are you sure that 4hp is enough for moving four people? You need to have very low weight and low rolling resistance vehicle to get anywhere with that little power. Four people alone weights around 320kg, add the weight of the panels, interior and structure and you are in vicinity of 700kg easily. Add batteries and that's ~800kg. I don't think 4HP is enough for that weight. First hill and you wont be going anywhere.

For batteries, I haven't any clue what is the cheapest lightweight battery. Usual lead-acid is probably cheapest, but it is far from being lightweight.

@timo we are trying for net weight including ppl as 450 kgs as for interior structure we are keeping it open golf car me abt various batteries avalable

That's very low weight. 450-320 is just 130 kg. You said you make a solar car with 4HP. That's about 3kW. To get that amount of solar you'd need about 15m^2 solar panels assuming they face directly to Sun. That alone weights quite a lot, probably more than what you have left after ppl. It doesn't leave anything for structure and interior not to mention batteries. And they are expensive: 3kW amount of relatively high efficiency solar costs around $20000 - $24000. I don't think that counts as "low cost" anymore. 15m^2 is also quite large area: 2m x 7.5m. Better panels just cost more. Weaker and you need more space and weight increases.

I think you need to think your project goals again, I don't think they are realistic. Solar is weak, expensive and panels are unreliable source of power in a car.

Pure BEV with some small solar panel to charge it while it is parked could work better, but then the cost is in the batteries.

@TIMO the car is mostly electric we are plaaning to very less percentage of solar ...the problem now is batteries .so wat is the cheapest li ion battery.

What are your requirements for kWh and weight? If these don't matter answer is lead-acid.

as a told u before the total weight of the car is 450 kgs and 3kw is enough for tht i u hav any gud ebooks on design of electric vehicles it would really help us

Timo means, what weight are you allocating for the batteries? Do you have a target weight in mind for them?

kw is NOT kwH. Kw is a measure of power, KWh is a measure of capacity. What Timo's asking is "how far do you want to go before your batteries are drained?"

i'm new, so maybe this has been discussed, but i thought constantly topping off batteries (the tesla model) hurt their longevity, and that it was better to let them run out completely. i know that's true in basic tech devices like phones, laptops, etc. any news coming from current owners on how the roadster batteries are performing years out, with hundreds of charges? sorry in french anyone know about batteries made by hydro-quebec nanotitanate li-ion faster charge 50 years expected life. this public company got long experience on electric car biggest hydraulic power producer in the world. old science tv show in french that show hydro quebec destroyed technology

Bobaffair, Li-ion battery life is optimized by avoiding the top and bottom 10% of the cell. Standard mode charging in the Roadster does this automatically, and I'm sure the Model S will be the same.

NiCads and NiNMH's benefited from the total drain before recharge, LiIons are not susceptable to the "battery memory" that those other two are, thus total discharge does them no favors.

From what I've read, it's the heat/cold from the charge discharge cycles that "age" a LiIon battery. Keep them temperature controlled, and they don't wear out as fast.

@timo we haven't decided on the battery weight ..and duration of running upto 8hrs max..
i am a beginner so i am very bad at deciding stuff can anyone give me info regarding design of car(links or pdfs)

3kW * 8h is 24kWh. That amount of Li-ion batteries cost somewhere between $4800 (very low, might not be available to you) - $12000 and weights between 80kg - 120kg, so that's doable, but not very cheap.

My main concern about your project is low power of the vehicle. Roadster uses 15kW just to maintain 60mph and it doesn't have very big air resistance (low, small frontal area). Even that you might get the car moving with just fifth of the power, it wont go fast anywhere.

If I calculate this correctly (need to be in meeting in two minutes) you can go about 8m/s = 30km/h max with that weight and rough estimation of drag with that little power in use.

Timo, perhaps a match with the Planar article you started the thread with, this research reports on using Lithium-Manganese on one electrode, and Tin-Carbon on the other!

Also reports charge densities in the range of 170 Kwh/kg so far. Combined with Planar's solid electrolyte system, could be a multiplier effect?

170kWh/kg would be 1000 times the current densities. I think you mean 170Wh/kg, which is about same range as current cheap Li-ion batteries.

Reading the article, they drop the specific energy density a lot more than planar energy batteries do. From 500 to 170, when planar did go from 700 to 400.

Yeah, I think that allowance for casing etc. is very conservative. Probably do a lot better than that with some decent engineering.

Holy Smoke! Aerogel Batteries and Capacitors?

But what kind of volume per unit charge would they require? Energy per kg. is irrelevant if it takes 1000 cu. m. to get a 1 kg. battery.

Why do I get a memory from Demolition Man "but, but, that's pure capacitance gel" BOOM!

If someone invents liquid batteries we get just that. On-road fast "charging" by "changing" batteries using liquids like gas & recharge at home when you can do it slowly.

Timo, Sorry to break in on this technical and pertinent discussion but I will try to be brief. First I agree the 'battery tech" seems the most important aspect right now. Now my question is, with your knowledge of batteries, do you see any developments in battery tech where the owner of EV could do things with any type battery{as yet not developed probably} that would promote the life of the battery with normal usage involved. Things along the line of maintenance procedures. Be nice if could buy battery and keep it going indefinititely with as yet unknown procedures. Hope you see my point here. Get longevity determined by the owner,of course range would be in the hands of the maker most likely.

You Finns get busy on this, bet you can come up with something.

I think this has been discussed before and a 500 mile range battery was mentioned as the magic mark as it was mentioned who wants to drive over 500 miles in one day.

There are already self-healing nanopolymers in testing for batteries. I don't think this kind of battery longevity enchantment techs are something Joe Average could ever understand, and even with those polymers it still isn't going to last forever, just a lot longer than we are used to.

Nanotechs are future techs. We have only scraped the surface of the possibilities yet, there are things visible only sci-fi writers could have dreamed of just few years ago (and then dump them as too unbelievable to write about).

Just in case you are talking about energies, physics laws still apply, there is nothing you can do that could extract more energy out of the battery than you put in.

That said, in theory silicon nanowire -based batteries could have way over 1kWh/kg energy densities, which is about four - five times more than any current tech. If you can get 300 miles out of current 3.1Ah batteries you could get around 1200 miles out of that same battery just few year later. Or twice the range with half the price.

No,no, timo not talking about energy. Think I have got this principle down now,ha.

Your talking my language now, not bound by what hasn't been done. Little train that could,yada, yada, yada. For somebody that all he knows about batteries is they have a positive and negative think I will give myself pretty good grade on conceptulazaton.

Thanks much for taking time to run through a little of this with me.

How about this?

It's an electrode design on the nano scale that dramatically increases current density for essentially any battery chemistry, readily scalable manufacturing.

1000C? That's, like, fast dude. Roadster battery is capable of something like 5C, that would be 200 times higher. Instead of 200kW you get 40000kW. Dragsters, beware.

I wonder if it is possible to break sound barrier in quartermile...


That would be fun!

I hope that technology is more promising than many other research successes that seem to fall off the face of the Earth shortly after publication. You'd think that something, somewhere along the line would be more or less readily applicable to EVs.

The glitch I see in the article I cited is that these are new electrode structures. On the good side, that may open doors to new and more effective geometries and form factors of cell design. But, it may also close doors on existing form factors, such as the 18650 form factor that Tesla currently works with. Maybe not.

Thin films I get - but I've never taken the time to find out exactly how Li-ion and NiMH cells work, nor to find out what configurations are currently in use.

As I understand, Tesla is pretty much the only ones that made a commercial success of the brute-force approach of stringing together thousands of individually packaged, off-the-shelf cells that were never intended for EV applications.

By comparison, General Motors, for example, designed a completely different cell geometry specifically for automobile loads. It seems as though others, like Ford partnering with LG Chem, are taking that general approach, as well.

Tesla supposedly has a relationship with Panasonic, from whom those new 3.1Ah cells for the 300-mile pack were sourced. Do you know if those were developed for EV applications specifically?

I guess, what I'm trying to find out, is whether Tesla is in a position that would be flexible enough to incorporate goodies like these new electrodes into new or existing form factors.

Elon said in one of the interviews (opening the factory I think) that those will be 18650 form factor cells, but modified heavily for Tesla. I don't know exactly what that means, but I'm guessing extra fuses, maybe lighter packaging than off the shelf batteries, things like that.

Panasonic has some skin in Tesla, now, and is probably working closely with TM to work up new technologies. The TM production runs are comparatively small, so it's a way to prove things out without a wholesale commitment to a new process.

well, single car equals around 1000 laptops, 20000 cars equals 20 million laptops. Not a small piece of production at that point anymore.

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