Tesla fans criticized cars like the BYD e6, yes. I thought it was too heavy, but I had no issue with the batteries. Others found fault with the batteries, but not those with experience with LFP like me, for instance. In fact, I did not at first understand what Tesla was doing with a clearly volatile, and fire-prone battery chemistry. Then I found out they were using special fire suppressant materials in their packs, and they used fusible links in series with each cell so that if a cell shorted out, it would blow the link. They also worked on their cell caps to reduce pressure in the event of outgassing. None of that could stop the greater volatility and susceptibility to thermal runaway and pack fire. It only reduced the spread speed, and gave time for occupants to exit. They armored the pack against puncture with a thick aluminum pan and gave it strong side supports. Every NMC and NCA pack will catch fire if punctured. Winston showed movies of LFP punctured by nails and bullets. Those are standard tests. There is a flame test, a bake test, and a full short test. (Don’t try this at home.)
Done right, LFP can be punctured with no fire. Tesla just went ahead and used NMC and NCA anyway, and dealt with it with clever countermeasures. As NMC went to more energy density with higher nickel content, it became even more volatile.
On top of the safety benefits, LFP has much higher cycle life, a minimum of 4,000 cycles, a stiff discharge profile, and very low internal resistance. It is a really good power source. Those of you with LFP Teslas or other vehicles, hang on to them. Their battery packs could last a lifetime.
In the recreational marine market, where fire is a beyond catastrophic event, everyone seems to have standardized on LFP for its safety characteristics. We’re replacing lead-acid (mostly AGM or sealed deep-discharge variants) batteries anyway, so just going to anything lithium-based is already a huge improvement in terms of weight, volume and storage performance.
LFP in Marine applications is mostly a cost driven choice, because the cost per kWh is 10-20% lower for LFP compared to NCA and NMC. NCA and NMC batteries are absolutely available for marine applications, and they store around 33% more energy for the same volume as LFP which makes them a good choice in space constrained applications. But, as you pointed out most marine applications are converting from AGM which is so huge that any Lithium based battery is a win.
If fire safety was the determining factor, LTO would be the battery choice rather than LFP. But nobody’s going to make that choice because LTO sucks compared to LFP.
