building my first Battery pack and got some questions

[Bigbikebob]

After completing couple of e-bike builds and a lot of troubleshooting I feel it's a good time to start looking into building my own battery pack drive the cost down. I feel I read enough to start asking questions

from what I understand there are variations of lithium battery chemistry.

Lithium Cobalt Oxide(LiCoO2) marked as ICR, LCO, Li-cobalt
Very energy dense. Can provide amps very fast due to low internal resistance which can be bad if things go wrong (they go wrong quickly). And has a short lifespan.

Lithium manganese oxide(LiMn2O4) marked as IMR, LMO, Li-manganese
High power and safety but less capacity then LiCoO2

Lithium manganese nickel(LiNiMnCoO2) marked as INR, NMC,
Which is more stable then the LiCoO2 and more energy dense then the LiFePO4
Used by some electrical cars and the zero motorcycle. This chemistry balances the pros and cons of LiCoO2 & LiCoO2

LiFePO4 marked as IFR, LFP, Li-phosphate
Is a very stable chemistry medium electrical density and has a long lifespan.

What is interesting is that Tesla uses:
Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) marked as NCA,Li-aluminum and NCR (for Tesla blend) for its cars and home battery, it is less energy dense then the LiCoO2 and safer but not as safe as the LiFePO4. So why go with LiNiCoAlO2?

So far so good?

For the more practical part of this post I would like to know:
1.Are there any other cells I should consider?
2.What I a reliable place to purchase battery cells?
3. I came a cross the Headway LiFePO4 and like the idea that you don't have to solder them but how is the conductivity when using such solution?

 

[Nobuo]

1. Based on Lithium you did a very good compilation, those are the most used ones. Then you also have LiPo/LiCo, the ones most used on RC stuff, also ebikes for experimented users. the most dangerous of all of them, good price, good energy density and lightweight. Now less used because safer chemistries are going cheaper, safer and increasing energy density.

2. check this: http://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

3. Do you mean using cooper tabs? is excellent, no differences with spot welded ones if they are right secured.

What is interesting is that Tesla uses:
Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) marked as NCA,Li-aluminum and NCR (for Tesla blend) for its cars and home battery, it is less energy dense then the LiCoO2 and safer but not as safe as the LiFePO4. So why go with LiNiCoAlO2?

Nowadays has very similar energy density than NMC.

It is also very safe, indeed the most of all lithium-ion cells. It resist better than the rest the self short circuit, and not virtually vulnerable for punctures, etc.

Also has any other unique characteristics as they can reach 2.5V while 3V is the common. Also can be completely discharged to 0V and far away harmed the same way other lithium-ion cells would be (Panasonic PF has amazing feedbacks as being discharged to 0V and stored for a couple of weeks, and then recharged and revived working normally (almost).

NCA chemistry has a very stable máx capacity reduction over cycles, when it reaches ~80% it keeps very close that máx capacity for the rest of its life.(there are some graphs of that on the sphere)

And the last one and not less important reason, because Tesla used massively that kind of cells, they are being manufacturated massively also and reached soon a very low price and that's why they become famous and used everywhere.

Panasonic NCR18650PF and samsung INR18650-29E are maybe NCA flagship cells today.

 

[Bigbikebob]

Nobuo,
Thanks for the detailed reply.

you also have LiPo/LiCo, the ones most used on RC stuff

If am not mistaken LiPo stands for lithium-polymer.

"Lithium-polymer differs from other battery systems in the type of electrolyte used. The original polymer design dating back to the 1970s used a solid (dry) polymer electrolyte that resembles a plastic-like film. This insulator allows the exchange of ions (electrically charged atoms) and replaces the traditional porous separator that is soaked with electrolyte

lithium polymer is essentially the same as lithium-ion. Both systems use identical cathode and anode material and contain a similar amount of electrolyte. Li-polymer is unique in that a micro porous electrolyte replaces the traditional porous separator. Li-polymer offers slightly higher specific energy and can be made thinner than conventional Li-ion

So it is not exactly battery type but rather a electrolyte that is used.and from my understanding it is mostly used with the LiCoO2 chemistry.

*LiCo is just another name for LiCoO2

2. check this: http://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

Pure good! Thanks

Do you mean using cooper tabs?

The Headway cells are connected with screws and Connectors such as this.
https://goo.gl/qkWbNS

NCA chemistry has a very stable máx capacity reduction over cycles, when it reaches ~80% it keeps very close that máx capacity for the rest of its life.

How does it compare to LiFePO4 in charge cycle number / lifespan?

Regarding safety:

"Lithium Nickel Cobalt Aluminum Oxide battery, or NCA, has been around since 1999 for special application and shares similarity with NMC by offering high specific energy and reasonably good specific power and a long life span. These attribute made Elon Musk choose NCA for the Tesla EV’s. Less flattering are safety and cost.

"NMC has good overall performance and excels on specific energy. This battery is the preferred candidate for the electric vehicle and has the lowest self-heating rate."

Li-phosphate has excellent safety and long life span but moderate specific energy and a lower voltage than other lithium-based batteries

So I am not sure that NCA is the safest option.

 

[Nobuo]

So about the headway is just the same conductivity you can get spot soldering on 18650 cells, nickel or copper(tinned) tabs works perfectly, the conductivity is perfect if the tabs are anti-corrosion tinned, or made of pure nickel. You just lose some space because the screws system.

besides from the unbelievable LiFePo4 safety --->https://www.youtube.com/watch?v=nMf6scF13lI

NCA are the next in safety, although is not as extreme, you can look for self-short circuit on NMC cells and NCA, and there is a difference. Panasonic NCR18650PF cells are really fool proof cell, but you are getting 3x energy density and x2 specific energy for the same price as LiFePo4 cells.

The greater difference in LiFePo4 is x2 - x3 cycles life. between 2000 - 5000, of course it depends from different manufacturers . So there are perfect cells for batteries that need to do various completes cycles a day.

Also LiFePo4 has a very stable 3.2V output between 3C and 10C discharges. So that's also unique.

 

[wesnewell]

After researching all the other chemistries over 4 years ago, I decided on rc lipo (LCO, lico or whatever else they call it these days) and I've never regretted it. I've never had a problem with it. The reason for choosing rc lipo was the energy density, weight, size, easy configurabilty, and cost. I haven't found anything better yet. I keep seeing promises, but nothing yet has hit the market that comes close to the bang for the buck.

 

[Bigbikebob]

unbelievable LiFePo4 safety --->https://www.youtube.com/watch?v=nMf6scF13lI

Very impressive.

NCA are the next in safety, although is not as extreme, you can look for self-short circuit on NMC cells and NCA, and there is a difference. Panasonic NCR18650PF cells are really fool proof cell, but you are getting 3x energy density and x2 specific energy for the same price as LiFePo4 cells.

The greater difference in LiFePo4 is x2 - x3 cycles life. between 2000 - 5000, of course it depends from different manufacturers . So there are perfect cells for batteries that need to do various completes cycles a day.

So both of this chemistry type are safe. The NCA is more energy dens for a fact while the statement that LiFePo4 has more life-cycles is an assumption that can be tested only after you use your specific cells.

And as I previously stated, Tesla went with the NCA chemistry and I am sure they considered life cycles

I decided on rc lipo (LCO, lico or whatever else they call it these days) and I've never regretted it. I've never had a problem with i

Good to hear.

I keep seeing promises, but nothing yet has hit the market that comes close to the bang for the buck.

IMO I think that the only party that are rely interested in this is Tesla and if some breakthrough will happen it will come from them.