LiPoly evolves while LiFePO4 is stagnant?

[liveforphysics]

I recently had a friend get one of the new thunder power 40/80c 5,000mAh LiPo packs for his RC car. This battery shows zero performance fade during operation. From the time you start using it, it feels like a fresh battery right up to the point the cell reaches full discharge and LVC kicks-in. These cells are rated for continous 40c, which is semi-impressive, but 50c continous has been done before by polyquest. What is shocking is that at 40c discharge the cell maintains over 90% of it's capacity!!! We did all manor of terrible things to this battery, and it always stayed cold to the touch. You can charge them at 10c too! That's just 6 minutes to charge (if you have a charger with enough power of course).

Here is a discharge graph to give you an idea of the cell performance:

I remember a couple years ago when A123's released the 2300mAh cell that swept the RC world. Everybody had a garbage can full of dewalt battery plastic casings at home. We were so wow'd by the power density that we forgave the worse energy density and additional weight. Most all top level guys were running A123 cells.

Now, fast forward time to the present. In competition RC, only grandma's and people with lipo-phobia use A123. All top level RC is completly dominated by high C lipoly.

What changed?

LiPoly design has managed to roughly tripple the C value in it's cells, and increase energy density at the same time. It has done this in just a few years, and continues to grow and improve rapidly.

So, that brings the big question, what has the development of LiFePO4 chemistry stone-walled? Unless I'm mistaken, the best performing cell you find is still the A123 2300mAh cell, which weighs the same as a 5000mAh LiPo cell, and has lower power density, and half the energy density.

I would think that due to the inherent safe properties that large amounts of RnD funds are being applied towards further improvement, but why has lipoly zoomed ahead while LiFePO4 takes a seat?

 

[stew007]

i'm a huge fan of lipos, and now with the combination of the current modern balance chargers, high c charge/discharge and anti puff packs they seem to be safer than ever. For raw power to weight ratio,energy efficiency and bike handling, lipos win by a country mile. The cost appears to be dropping now too, those 4ah cells on the other thread were dirt cheap. I would not want to take a step back to heavy batteries again. having charged these cells many hundreds of times with not a hint of drama, but I admit I do use my outdoor charging station for peace of mind :lol:

 

[thomas]

How many cycles do you get from a good lipo battery compared to lifepo4?

 

[Ypedal]

I'd like to find someone that can tell me and show proof that they put 2000 cycles ( deep cycles too.. ) on an EV app. using LiFePo4.. the years are ticking and we should start to see stories about it pretty soon.. ( The RC guys with multiple deep cycles per day are likely the 1st to report on that .. )

For winterbound people like us maritimers, 100 cycles per year is about the max.. so even lipo at 300 cycles is 3 years of use.. Unless this LFP tech can stay in shape for 10 year service life lipo is just as good if it was Safe..

In my younger days i've played enough with things that go BOOM to learn that a cap full of gun powder makes a bad enough " Woops, Whoa.. that sucked... " .. and a 2 Liter pail of it kills you.. similar thing happen with battery packs.. a cell phone pack goes Pop.. a 72v 40ah Lipo pack.. well do the math.

 

[TylerDurden]

Lotsa patent wars raging in the LFP world.

 

[jondoh]

prices are high but specs are impressive. for $1600, you can have a 36v/16ah pack that weighs around 10 lbs-- but that's if the bms can handle being connected in series. Actually, it would be better if you could put three in series but then you're talking about a lot of money.

My good old emoli milwaukee packs are chugging along. I still use one pack that's like 3 years old. Works fine but it's a little slow to charge. I'm going to post an update on my rides and battery packs soon. It will give me a chance to rant about how batteries aren't just all about cell technology, but rather bms, connector quality and general construction quality too. If i had the money, i *might* take a chance on a lipo battery pack build if the bms was ok.

 

[liveforphysics]

I can absolutely understand why many folks would want a safe chemistry for E-bikes and lots of other things. Safe chemistries are awesome and certainly have there place in the world.

I'm not trying to start a one battery type vs another thread.

I'm simply puzzled as to why one battery technology is improving by leaps and bounds every year, while the other has apparently made no improvements for a few years (at least nothing I've been aware of).

It makes me more puzzled when I assume that the big corporate money has gotta be mostly all going into the safe chemistry designs, yet where are the improvements?

Is there some inherent chemical storage plateau limitation with the safe chemistries? Can the cells reach a point where high C discharge doesn't result in a large drop in amp hours?

TD- Are these lawsuits preventing companies from researching battery improvements? Or perhaps limiting them from announcing them?

 

[liveforphysics]

Jondoh- For $1600, you could make a staggering 55Ah 36v LiPoly pack capable of a constant 1,100amps!
Or, you could make a more reasonable 36v 19.6aAh pack for just $560, and be capable of a sustained 392amps.

Maybe it's just because of the 10k+ platinum hobby city member discount prices, but LiPolys are really not very expensive anymore.


I agree though, BMS is crucial for any pack. It seems Lipoly is getting left in the mud for packs over 12s getting decent BMS, while the safe chemistries have lots of options.

 

[pgt400]

PSI / Lifebatt is introducing a 14 AH cell.....same size as their and Headways 10 AH units now available...... I'd call 40% more capacity a major improvement!

 

[Doctorbass]

Jondoh- For $1600, you could make a staggering 55Ah 36v LiPoly pack capable of a constant 1,100amps!
Or, you could make a more reasonable 36v 19.6aAh pack for just $560, and be capable of a sustained 392amps.

Maybe it's just because of the 10k+ platinum hobby city member discount prices, but LiPolys are really not very expensive anymore.


I agree though, BMS is crucial for any pack. It seems Lipoly is getting left in the mud for packs over 12s getting decent BMS, while the safe chemistries have lots of options.

I agree that Lipoly are growing in popularity. Their cycle life is half the LiFePo4 and that's why EV development is not so intersted in

Electric car need a cell that can handle high current with minimal life loss.. so i would consider a cell in:

how many kWh this cellcan exchage in energy in it's entire life... ex 30Wh at 2000cycle at 1C = 60kWh of stored energy in the entire life of a cell...

One big advantage of teh Lipoly as my lithium manganese have too is that they have a higher voltage! so that mean for a given pack voltage you have less chance to get bad cell problem, les ch in a bms mean less potential problem.. cheaper bms price etc..

To get 88.8V nominal out of my lithium manganese pack (same V as Lipoly) i need 24s and you would need 28 cell of LiFePO4 to get the same voltage.. thats 11% more risk and $ with LiFePO4..

The only negative points about Lipoly is that their form factor make them less robust to mecanical endurance and the fact that they are pouch closely stacked together make the center cells more vulnerable of overheating or creating bad thermal management .. that affect cycle life and performance too!

Cylindrical cells help air to circulate between them equalizing overal heat between cells.

I admit that 200A out of these pouch tabs seems incredible!.. I would be curious to know their temp at the end of 40C discharge and also their nominal internal resistance!

Doc

 

[MitchJi]

Hi,

PSI / Lifebatt is introducing a 14 AH cell.....same size as their and Headways 10 AH units now available...... I'd call 40% more capacity a major improvement!

Same weight or heavier?

Anyone know what the price will be (about the same or about 40% more)?

 

[recumbent]

When Justin went across Canada last summer he also used Lipoly cells for the majority of cells if i remember correctly.

I was tempted often to purchace these cells because of the weight and size advantage which is a big deal for me because i mount my batteries behind my seat which is only 5 inches wide at the narrowest point. There is no better compliment when I hear someone say "Oh, your bikes electric, i didn't know that, where's the battery ? " And this happened often.

Who is the best supplier of Lipoly batteries for ebike power range of 48 volts?

 

[liveforphysics]

PGT400- Hey! Now that's what I was looking for! 40% energy density (at least with respect to volume) improvement! Fantastic news! I'm very glad to hear that!

Now I'm not quite as puzzled. Very good to hear that the technology is improving in the safe chemistries batteries.


As far as life-cycles with LiPoly batteries, I know of some RC helicopter guys who have packs cycled into the 4-digit range. You rarely ever see LiPoly cell capacity drop below 80-85% of new capacity unless you do something to damage the cell.

Best Wishes,
-Luke

Be

 

[pgt400]

Hi,

PSI / Lifebatt is introducing a 14 AH cell.....same size as their and Headways 10 AH units now available...... I'd call 40% more capacity a major improvement!

Same weight or heavier?

Anyone know what the price will be (about the same or about 40% more)?

Well since their from Lifebatt, you can bet they will be priced too high to actually buy! Our best bet will be when Headway follows suit. The other possibility is that this will cause the 10 AH PSI cells will come down in price.

 

[liveforphysics]

Do you happen to have any idea of the discharge rates of the new cells?

 

[methods]

Who is the best supplier of Lipoly batteries for ebike power range of 48 volts?

Zippy.
They have at least 10 different sub brands:

Rhino:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=7657
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=7300

Zippy H:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=6415
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=6353

Zippy R:
http://www.hobbycity.com/hobbycity/store/uh_message.asp?message=Cannot+get+product+details.+Please+contact+us+to+request+more+information+about+item

Zippy:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=7638
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=7639

This is the best value for a high power 6S charger on the market in my opinion
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=6792

This is the best value for balancing in my opinion
You balance with these by overlapping the 6th channel of the first box with the 1st channel of the next (for long series packs)
This thing will also shut the power off if you go over 4.25V and beep like hell if you go under 3.0V or have any two cells out of balance
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7443&Product_Name=CY-_B6_plus_balancer_(2-6S_series)

You can get cool toys like this:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idproduct=6748

There are companies like Chargery who make AWESOME stuff at AMAZING prices
http://www.chargery.com/

Chargery even makes a 1A balancer. Look at all this gear. Accurate to 0.005mV !!!
http://www.chargery.com/doc/Chargery%20charger%20list%20v3.3.pdf

The place where you shop is Hobby City
http://www.hobbycity.com/hobbycity/store/uh_index.asp
The more you buy the bigger the discounts you get.
Every item has a "true review" ignore the stars, read the reviews
Reviews with 1-2 stars get deleted. If you want to make a poor review
then give it at lest 4 stars. People know. . .

The way you hook up all these batteries is in true parallel
If you want to make a 48V pack you buy 4 of those packs above

That makes a 2S 2P battery that is actually a 12S 2P
44.4V @ 10Ah

On the parallel packs hook all the balance taps together in parallel
This will cause the batteries to self balance to a degree.
Also cuts down on bms costs

You can use the 24Channel BMS that we have here on this board.
I have already done it
You only have to change R101 and the TC54
Same price.


Does that answer your question :wink:

-methods

 

[MitchJi]

Hi,

Hi,

PSI / Lifebatt is introducing a 14 AH cell.....same size as their and Headways 10 AH units now available...... I'd call 40% more capacity a major improvement!

Same weight or heavier?

Anyone know what the price will be (about the same or about 40% more)?

Well since their from Lifebatt, you can bet they will be priced too high to actually buy!

There are other sources than Lifebatt. Here for example:
http://endless-sphere.com/forums/viewtopic.php?f=9&t=7390

 

[Jozzer]

Other places to buy 14AH cells? As far as I am aware these are a LifeBatt only product, developed by people employed by LifeBatt. They spent a lot of cash to develop these, I for one will understand if they come at a premium until they have paid for themselves. I don't mind paying a company that continues to improve its products.
Same weight/size as the 10AH, making them about the highest wh/kg available in LifePo4 (and very close to Lipo's too)

 

[recumbent]

Does that answer your question

Oh yeah, and each 22volt brick is less than 800 grams, over 20-C, and wired for plug & play, 8) now that is sweet.

The charger has a USB plug, and a drain to-test also, nice.

I could also put together a small (5A/hr)bundle for back-up to carry me home when i run out of juice.

 

[MitchJi]

Hi,

Other places to buy 14AH cells? As far as I am aware these are a LifeBatt only product, developed by people employed by LifeBatt.

They spent a lot of cash to develop these, I for one will understand if they come at a premium until they have paid for themselves. I don't mind paying a company that continues to improve its products.
Same weight/size as the 10AH, making them about the highest wh/kg available in LifePo4 (and very close to Lipo's too)

Thanks for the clarification.

I thought LifeBatt Cells were made by PSI. Who makes the 14ah cells?

Any idea of the price?

Thanks!

Mitch

 

[AndyH]

Other places to buy 14AH cells? As far as I am aware these are a LifeBatt only product, developed by people employed by LifeBatt. They spent a lot of cash to develop these, I for one will understand if they come at a premium until they have paid for themselves. I don't mind paying a company that continues to improve its products.
Same weight/size as the 10AH, making them about the highest wh/kg available in LifePo4 (and very close to Lipo's too)

Jozzer, I got a head-up from PSI months ago that 14AH were the cells under development and testing. Sorry, mate - marketing speak aside - these are PSI cells.

 

[methods]

I could also put together a small (5A/hr)bundle for back-up to carry me home when i run out of juice.

Dude, that is an awesome idea. . .
I have carried a 12S2P 44V 10Ah pack as backup before but (that killed me) and it never ocured to me to just bring a "spare air" pack
A pack just big enough to say. . . Drag the weight of the bike
22.2V 5Ah. . . Just enough to make it so that I can pedal with my riding gear and not die.
Or even enough to make it so that I can walk the bike up hill (my bike is like a motorcycle)

I really like that. I am doing that for sure!

hrm. . .
Would need to turn off the LVC on the Kelly permanently and turn off the LVC on the CA on the fly
All the other functions of the CA would work so the battery could be protected.

Yea, that is bad arse.

-methods

 

[safe]

Let's not forget that LiPoly is still the equivalent of a nuclear power plant... it can meltdown on you.

LiFePO4 came on the scene primarily to provide safety, so they have not had any incentive to push the limits of performance.

LiPoly would have died off if it didn't find a new "niche" to fill.

If you want:

Low Weight
High Power (High Discharge Rates)
Fast Charging
Low Prices

....then you choose LiPoly.

If you want:

Safety

...then you choose LiFePO4.

If you want to have a low entry price you use SLA's or NiCads or NiMh.

However... these prices are getting so good that even I (the cheapest man on endless-sphere) am starting to pay attention to it. :lol:

 

[voicecoils]

Jozzer, I got a head-up from PSI months ago that 14AH were the cells under development and testing. Sorry, mate - marketing speak aside - these are PSI cells.

Could the difference in 10Ah vs 14Ah be the percentage of Phostech cathode powder? Have the relative power density / energy densities changed from the specs of the 10Ah cells?

P.s. I'm told my package from you has arrived, I should be seeing it downunder in the next 2 weeks 8)

 

[AndyH]

Jozzer, I got a head-up from PSI months ago that 14AH were the cells under development and testing. Sorry, mate - marketing speak aside - these are PSI cells.

Could the difference in 10Ah vs 14Ah be the percentage of Phostech cathode powder? Have the relative power density / energy densities changed from the specs of the 10Ah cells?

P.s. I'm told my package from you has arrived, I should be seeing it downunder in the next 2 weeks 8)

I'm glad the package made it! Enjoy the new toys!

I really don't know about the effects of Phostech powder. Marketing BS seems to cloud the real value of the stuff. We have plenty of reports from cells that we KNOW do not have Phostech, but we don't have results for cells that we know for sure HAS the stuff...and then we have no idea how much they used. And that huge 'grey area' gives marketers the ability to say what they want - and actually mean it. I suspect Phostech has more to do with C rating than capacity, but I'm not a chemist and that's nothing more than a guess.