New battery type LFP or LiFePO4 Lithium Iron Phosphate Battery

[Krish]

2 days ago my olderson Took posecion of a new Tesla car, which uses a different battery, in talking with him he told me it is an LFP battery type which I researched and found it is actually a new technology battery and correctly is a
LiFePO4 Lithium Iron Phosphate Battery.

It has better performance than our regular LiPO cells and are avaialable on Amazon.ca. but are costly at this stage just as LiPO were, but I suspect they will reduce in time, they are based on Fe (Iron) which is 32% of our planets crust hence very common with Oxygen being the next in the Periodic Table.

Lets wach for them. Elon Musk is already shipping them in his new cars! I now know its benefits for our R/C planes!

[Andrew Fernie]

Some of the advantages of LFP of Li-Ion are cost, safety (flammability and thermal runaway), cycle life, can use more of the energy without damaging the cells, and avoiding the use of nickel and cobalt. The main downsides for us are the specific energy (stored energy per unit weight), and not available at very high discharge "C" ratings.

Also need to consider the voltage. They are generally around 3.2-3.3V vs. 3.7V for Li-Ion. Not a fundamental problem, but you do need to make sure that you consider this when configuring a pack.

[Krish]

Hey Andrew, as far as I know, the Li-Ion cells offer the most unstable of the litium cells, they were prone to explode or burn while in use in cell phones or even in our R/C use and would not tolerate any over charging and hence more dangerous than LiPo's!.
The new LFP are conserably more stable and has good dischare capacity else Elon would not use them in his new cars? I suspect?
But time will reveal all the negatives about them.lol!

I do not yet know about their voltage levels for our use as yet, although Amazon.ca are only listing units for 12 Volts at this time, I didnt see anything else as yet. I will seek more info on them now!

[Krish]

LFP Battery Cell Voltage
Due to the difference in various raw materials used by each manufacturer(including positive, negative electrode materials, and electrolytes), the performance and voltage of the batteries are not exactly the same. In general conditions, the nominal voltage of the LFP battery cell is 3.2V, the high-end voltage is 3.6V, and the low-end voltage is 2.0V.

The charging voltage of the LFP battery cell is recommended as 3.65V, 14.6V+-0.2V for a 12.8V battery. 3.65V per cell is proven to be a reasonable charging voltage after long-time practical use.

The relevant voltage of the LFP battery is different in different conditions. Mainly in 3 cases, open-circuit voltage (OCV), charging condition, and discharging condition. In applications, the charging and discharging voltage are more useful, involving a reasonable set of end voltages to ensure that the battery works in a good and stable situation.

[Andrew Fernie]

Hi Krish,

Should have read "LFP vs. Li-Ion" - where LFP is short for LiFePO4. LiPo is a class of Li-Ion with a polymer electrolyte. so whether Li-Ion or Li-Polymer, yes, these are the flammable/subject to thermal runaway batteries. The LFP are safer, and this is one of the reasons they are being used. The tradeoff is the reduced specific energy, so with LFP you need to carry more battery weight for the same flight time.

The standard test for behavior when damaged is a nail penetration test - here is one on YouTube https://www.youtube.com/watch?v=Bg_480HUheo that tries both NMC (one of the Li-Ion chemistries) and LiFePO4.

The nominal voltage of LFP is around 3.2V vs. about 3.7V for Li-Ion so on a 4S you get about 2V lower. Fully charged is about 3.65V vs 4.2V, so a bit more than 2V difference for 4S.

I am not ready to power an aircraft with them, but do have them in a TX pack.

Andrew

[MichaelLevy]

There appears to be new Li-ion batteries that are safer than the older ones and may eventually replace lipos.
https://www.youtube.com/watch?v=pgns5UD2jw4&feature=youtu.be