# LFP Prismatic, Volt cells or Leaf cells??



## Semper Vivus (Apr 13, 2011)

Hello,

maybe a more generic view on that:

The alternatives, you mentioned, are both no LFP cells. By now I also don't know any OEM, that is using Lithium Iron Phosphate in a EV or HEV.
Both are oxide chemistries. That is, the cathode consists of nickel, manganese, cobalt or some mixture of them (NMC).
The main difference between them are:
1. Flat discharge curve with LFP vs. a steeper discharge curve with oxide chemistries.
2. A lower nominal operating level with LFP (about 3.2V).
The first point is one key issue, why you won't find a LFP cell in a OEM HEV, where the battery is only operated in a small SoC area: Determining the SoC based on the voltage is very hard.
The second point is why you won't find a LFP cell in a OEM EV: The energy densitiy is lower.

Regarding the pros and cons for a diy EV, I would say:
- Leaf, if you want a little more energy density.
- Volt, if you want higher continuous power because of the integrated water cooling.
- 18650 if you want the highest energy density.
- LFP prismatic if you just want to have the easiest way of build and installation.

In my opinion safety isn't a argument in the discussion LFP vs. oxide, if it is for a diy EV. Issues like installation and battery management do have much more influence here compared to the chemistry.

Regards,
Tom


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## Karter2 (Nov 17, 2011)

> ....I also don't know any OEM, that is using Lithium Iron Phosphate in a EV or HEV.


The Fisker Kama used A123 20Ahr pouch packs, which are a version of LiFepo4, and are very desire able cells for a high power pack.
I know it is currently out of production, but it is reported to be returning soon, and there may well be a supply of reclaimed cells from those initial production cars.
Those cells have also been used in several commercial EVs ( Bus's, trucks, Vans etc)
also the A123 cells are still available new via A123 authorised A123 retailers.


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## dougingraham (Jul 26, 2011)

Semper Vivus said:


> By now I also don't know any OEM, that is using Lithium Iron Phosphate in a EV or HEV.


The Chevy Spark was going to use LiFe cells from A123 but that changed when A123 went down with the Fiskar Karma issue.

I don't know what they ended up using in the Spark but probably the same as what is in the Volt.


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## Hollie Maea (Dec 9, 2009)

Karter2 said:


> The Fisker Kama used A123 20Ahr pouch packs, which are a version of LiFepo4, and are very desire able cells for a high power pack.


The best power 18650s can actually match these cells in terms of power density:

The Samsung 25R has just barely higher weighted DC resistance (1035 miliohm-grams for the 25R vs 992 milliohm-grams for the Amp20) while it has 1.5 times the energy density (200 Wh/kg vs 129Wh/kg).

The A123s have a higher C rating, but that's largely due to the lower energy density.


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## Karter2 (Nov 17, 2011)

Certainly there are better cells ( energy density, power density, value , etc etc), but i thought the OP was comparing salvaged pouch packs..Volt, Leaf , etc to large LiFP prismatic s ( Calb etc).
I dont know if the OP has interest in 18650 pack building, or of any sources for large quantity of recycled 25R cells to compare on a "value" basis, but i guess he could at least consider recycled Tesla modules for a comparison ?


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## puddleglum (Oct 22, 2008)

I appeciate everyones comments and it's all good information. Hopefully it could benefit others as well as me. I would probably not want to build a large pack from 18650 cells personally although I have considered doing an e-bike pack with laptop cells. I do admire those that have done it sucessfully though.
My own assesment of the pros and cons is as follows, Please feel free to correct me or ad something I've missed:
Good 18650's like the 25R's are as expensive or more expensive than prismatics, and while the energy density and low weight are their big advantage, the difficulty of assembly for the average DIY guy is a huge minus and cycle life is not as good as prismatics which makes the cost/charge cycle even higher. 
Prismatics are expensive to buy and the heaviest of the lithiums (cons), but they are the easiest to assemble and manage, have a long cycle life so cost per cycle is not too bad.
Leaf cells have a relatively low cycle life and life expectency of used ones might be limited, availability is limited, but the up front cost could be a lot less (if you can find good used ones) and they don't appear to be really hard to reconfigure and work with. They are lighter than prismatics.
Volt cells require water cooling which adds to the cost and complexity of reconfiguring the pack (any ideas of how much?) and availability is very limited (cons). Pack has good output for the weight and may have a good cycle life if they can be monitored properly. If you can find used packs, up front cost is lower and, if you could use complete modules, they might be manageable to reconfigure a pack. I found replacement packs being advertised for $3000 new, but I have no idea if it is for real. Does anyone know if battery management is more important on one chemistry than another? That would effect cost as well.
Is that about right? Am I missing something? Personally, I'm trying to decide what is the best battery choice for a low budget commuter car that I could drive trouble free for the next 10 years or more.


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## kennybobby (Aug 10, 2012)

Battery management (both thermal and electrical) is important for all of them-- whether that is automatic or manual determines the cost.

Obviously te$la is at the top of the food chain with their awesome thermal system and constant monitoring.

But diy packs without cooling or BMS do the job with just manual control by the owner.


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## piotrsko (Dec 9, 2007)

I don't understand why everybody is obsessive on using the water cooling jacket on the volt pack.

It is nice to have for piece of mind, but I haven't seen it useful for anything more than to provide mass stability and to warm up The pack below 80 degrees.

My average temperature rise on a trip is only 10 degrees.


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## Karter2 (Nov 17, 2011)

piotrsko said:


> I don't understand why everybody is obsessive on using the water cooling jacket on the volt pack.
> 
> It is nice to have for piece of mind, but I haven't seen it useful for anything more than to provide mass stability and to warm up The pack below 80 s.


^^+1
The more I read about these "pack thermal management systems" , the more I am convinced they are for compensating for ambient conditions.....IE,. Primarily warming the pack in cold regions , and cooling the pack in hot (Texas ? ) days. 
Regen (+ braking !) is especially affected by cold pack temps, and regen into cold packs is very bad for cell life.
On a Tesla, cooling during Supercharging may also be needed (in Texas !) ,....
...but I do not believe they were intended as cooling systems to deal with high rate discharge issues.


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## puddleglum (Oct 22, 2008)

I get that management of some kind is necessary and I would defintitely need a heating system (it's too cold for batteries here most of the year) whatever pack I may get but one may be easier to build than another. Trying to determine if one chemistry is more expensive to manage than another. It would seem like a 60 cell pack would be harder to keep in balance than a 600 cell pack but that may or may not be the case. Bms systems add substantial cost to a budget build where it is a small percentage of a large pack like a Tesla pack. Piotrsko, it's good to hear from personal experience. Are you happy with the volt cells? How did you find them to work with?


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## piotrsko (Dec 9, 2007)

I'm happy. They were plug and play for the equivalent FLA pack. No monitoring, no other issues, no balancing. Chevy did a monster job engineering these to be bullet proof (almost).

I originally Ran a FLA cycle on the elcon for charge, with an abrupt termination, got the elcon reprogrammed only to extract another KWH.

NOW I realize I didn't know anything about these and there was nothing for documentation that wasn't contradicted by "experts".

Still waiting for all these "experts" to reverse engineer the bms and other systems and publish working adapters, but IMHO, @ $0.15 a Wh I could afford to destroy the pack back then with experiments.

Had I known then what I know now, I would have gotten the harnesses and the Volt battery manager/charger unit but only to use the commercial stations for recharge.


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## puddleglum (Oct 22, 2008)

It's great to hear that the volt packs can be run without active management and not have balance issues. Being able to charge them using a lead acid charger and have it work fine is quite interesting as well.


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## piotrsko (Dec 9, 2007)

Caveat on FLA charger: you either need cell counts that tolerate the 14.50 v per battery the charger outputs, or you externally switch it off when your cells get to 4.1


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## JCC (Mar 19, 2015)

The prices of Volt, Leaf, Prius, etc batteries seem too good to be true. With them being used, I would imagine that the cells are worn out. For those who currently use them, are you satisfied or disappointed?


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## Karter2 (Nov 17, 2011)

JCC said:


> The prices of Volt, Leaf, Prius, etc batteries seem too good to be true. With them being used, I would imagine that the cells are worn out. For those who currently use them, are you satisfied or disappointed?


 Cannot answer from personal experience, but there are plenty of posts from folks using these cells with few problems.
Why would they be "worn out" ?
These are cells/packs from collision damaged vehicles ( +some flood damaged Leafs ), and I doubt there are many of those with high mileage as they have not been on the market long !
It will be a few years before you have to seriously consider the calendar age of the older packs when they come up for sale.


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## JCC (Mar 19, 2015)

Karter2 said:


> Cannot answer from personal experience, but there are plenty of posts from folks using these cells with few problems.
> Why would they be "worn out" ?
> These are cells/packs from collision damaged vehicles ( +some flood damaged Leafs ), and I doubt there are many of those with high mileage as they have not been on the market long !
> It will be a few years before you have to seriously consider the calendar age of the older packs when they come up for sale.


When I refer to "worn out", I mean to refer to noticeable performance loss. I know with enough cycles, the cells will degrade, but I don't know how quickly these batteries will degrade. I've seen how quickly laptop and phone batteries degrade; however, I don't know how many more cycles these vehicle batteries can do versus normal laptop batteries. I do know that these batteries are usually over-engineered for better protection.


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## Kevin Sharpe (Jul 4, 2011)

JCC said:


> For those who currently use them, are you satisfied or disappointed?


We're picking up our second salvaged 2015 "Gen 2" Leaf today and this is the third Leaf battery pack we'll be using. None of the cars had been driven more than 6,000 miles and as far as I can tell the cells are in excellent condition.

I will investigate whether battery cooling/heating will be beneficial but given the temperate climate in the UK I doubt it's worth the hassle because we have "Gen 1" Leaf drivers who've driven more than 1000km in 24 hours using rapid charging.

If you can cope with the module format then I think these are excellent cells with a simple upgrade path from 60-62-64Ah. With the launch of the 2016 Leaf I expect "Gen 1" and "Gen 2" modules and car prices to fall dramatically.


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## puddleglum (Oct 22, 2008)

JCC said:


> When I refer to "worn out", I mean to refer to noticeable performance loss. I know with enough cycles, the cells will degrade, but I don't know how quickly these batteries will degrade. I've seen how quickly laptop and phone batteries degrade; however, I don't know how many more cycles these vehicle batteries can do versus normal laptop batteries. I do know that these batteries are usually over-engineered for better protection.


Cycle life is one of my questions as well. I have read of a few Leaf owners that have noticed reduced range. Haven't seen anything about Volt cells. In fairness that may or may not be the fault of the cells, there are other factors Like temperature, DOD and such. I don't think it is fair to compare Leaf and Volt cells to laptop cells though. I think they are a lot better cells than those. 
I don't know if anyone would have the opportunity would be able to find out the condition of the cells from a wrecked pack but you could at least find out the mileage on the car.


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## dcb (Dec 5, 2009)

puddleglum said:


> Personally, I'm trying to decide what is the best battery choice for a low budget commuter car that I could drive trouble free for the next 10 years or more.


Sounds about right, the leaf/volt cells seem to be the best bargain per kwh, and it is like tilting up walls vs laying bricks when compared to a 18650 build.

60ah is a bit much for my bike project though in leaf cells, so I'm looking at the calb ca40fi, which are still about 40% less expensive than the 18650 (best I've seen is about $6.50/cell, PLEASE someone post a link if they know better), or I should reconsider my motor selection, but it is a great fit for the 40ah'ers in terms of peak and continuous operation and ease of assembly, though it would probably be less expensive at this point to go with the leaf modules and shop for a better suited motor or something now that I think about it.

Edit, if it is just a commuter, do be sure to price a used leaf (or imev, or??) in your area too. It may be a bit like heresy here, but if is gonna cost about the same to convert something vs buy something with all the creature comforts (ac, battery heaters, reverse camera, gps with charging station finder, chademo and built in charger, etc etc) then you should definitely consider it.


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## puddleglum (Oct 22, 2008)

dcb said:


> Edit, if it is just a commuter, do be sure to price a used leaf (or imev, or??) in your area too. It may be a bit like heresy here, but if is gonna cost about the same to convert something vs buy something with all the creature comforts (ac, battery heaters, reverse camera, gps with charging station finder, chademo and built in charger, etc etc) then you should definitely consider it.


I agree with you except they don't exist around here, used or even new. This is oil country. There are a few Volts but very few and they are still way out of my price range. Even if I could find a used pack it would need to be from back east. I'm in no hurry though. I've been dreaming of this for a long time and it will likely be a dream for some time yet. At least I should be prepared, haha.


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## riba2233 (Apr 29, 2015)

dcb said:


> 60ah is a bit much for my bike project though in leaf cells, so I'm looking at the calb ca40fi, which are still about 40% less expensive than the 18650 (best I've seen is about $6.50/cell, PLEASE someone post a link if they know better), or I should reconsider my motor selection,



18650 cells are much cheaper than lifpo4 prismatics these days. Of course, you need to assemble tham, but only thing cheaper then them are leaf or volt cells.

Same C rate as winstons:


http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html

http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-29e.html

High C rate:

http://eu.nkon.nl/rechargeable/18650-size/samsung-18650-inr18650-25r.html

There are also cells that have larger capacity for same C rate, but are still more expensive. They cost about same as lifepo4, but have even better energy density:

http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-35e.html


Capacities are getting bigger, and prices are getting even lower each year. Last year I bought Samsung 29E for my moped for 3.9€ per piece, and now I can buy them for 2.4€. And for 3.85€ I can buy Samsung 35E, which have 20% more capacity in same volume.

There are also some super cheap cells, with bit lower energy density, but bit better C rate (and older chemistry):

http://eu.nkon.nl/rechargeable/18650-size/samsung-icr18650-22p.html

http://eu.nkon.nl/rechargeable/18650-size/sony-us18650v3.html

But I recommend newer cells with NCA chemistry (all of the above).


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## rwaudio (May 22, 2008)

puddleglum said:


> I agree with you except they don't exist around here, used or even new. This is oil country. There are a few Volts but very few and they are still way out of my price range. Even if I could find a used pack it would need to be from back east. I'm in no hurry though. I've been dreaming of this for a long time and it will likely be a dream for some time yet. At least I should be prepared, haha.


There are used leaf's popping up in the Calgary area for 15-20k depending on year/model, not the sub 10k they are seeing in the US, but still a good deal. Of course I'd opt for a conversion (since I can't afford a Model S P85D... or any of them).
I bought a Volt pack in Edmonton for 1200CAD, got another one from a wrecker in Lumby BC for $1600CAD shipped, they come up from time to time, I'm looking for a couple more myself. I've never seen a leaf/tesla pack but there have been some that sold quite quickly.


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## puddleglum (Oct 22, 2008)

rwaudio said:


> There are used leaf's popping up in the Calgary area for 15-20k depending on year/model, not the sub 10k they are seeing in the US, but still a good deal. Of course I'd opt for a conversion (since I can't afford a Model S P85D... or any of them).
> I bought a Volt pack in Edmonton for 1200CAD, got another one from a wrecker in Lumby BC for $1600CAD shipped, they come up from time to time, I'm looking for a couple more myself. I've never seen a leaf/tesla pack but there have been some that sold quite quickly.


That is interesting that there are some Leafs in Calgary but considering my moto is "as cheap as possible and free is better" I want to go the conversion route. 
if I could find a pack for that price, I could probably do a conversion for under $4000. I'm hijacking my own thread though and getting off topic, haha


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