Charging Recommendations & Best Practices for the LFP battery in the Fathom

[onuiebvbevnulib]

LFP (Lithium Iron Phosphate) vehicle batteries typically last between 2,000 and 8,000 charge cycles—retaining 70% to 80% of their original capacity—which is roughly double the lifespan of traditional NMC (Nickel Manganese Cobalt) batteries.

What is a Charge Cycle?

• Definition: A full charge and discharge of the battery's usable energy range (0% to 100%).
• Partial Cycles: Using 50% of the battery today and 50% tomorrow counts as a single full cycle, not two separate ones.

LFP vs. NMC Cycle Life Comparison

• LFP Batteries: Rated for 2,000 to 8,000 cycles depending on depth-of-discharge and manufacturer engineering (e.g., often quoted around 3,000–4,000 cycles to 80% health, or up to 6,000–8,000 cycles under specific test parameters).
• NMC/NCA Batteries: Typically rated for 1,000 to 1,500 cycles before dropping to similar capacity thresholds.

Charging Recommendations & Best Practices
Automakers and battery researchers provide specific guidelines for maintaining LFP packs:

• Regular 100% Charges: Unlike NMC batteries (which prefer an 80% daily cap), LFP packs use a flat discharge curve, meaning they need a full 100% charge periodically—weekly (as recommended by Tesla) or monthly (as suggested for the Ford Mustang Mach-E)—to allow the Battery Management System (BMS) to accurately recalibrate state-of-charge estimates.
• High State-of-Charge Debate: While automakers recommend charging to 100% for calibration, recent battery studies (including research co-authored by Jeff Dahn) indicate that leaving LFP cells parked or continuously cycled near the very top (75%–100% SOC) for extended periods can accelerate minor electrolyte side-reactions.
• Daily Driving Window: Keeping daily usage flexible (such as between 20% and 80%) can minimize long-term voltage stress, provided you still top it up to 100% on your designated calibration schedule.
• Storage State: If storing an LFP-equipped vehicle for a long time, manufacturers like Ford recommend leaving the battery at a lower state of charge—around 50%—to reduce internal voltage stress.

Alan Clarke stated that Ford will highly recommend that the Fantom be charged to 100% every night so that the full range is available every morning. The analogy he used is for your cell phone to be charged overnight and in the morning you see 100% so you have no worries about it being unavailable during the day.

Since I am retired and drive such short trips (only 4,000 miles yearly) I will follow the Tesla practice and charge to 100% weekly. If I am having a long 100+ mile trip I will charge to 100% the night before.

The reason for weekly instead of daily is this study:

LFP Battery Health Degrades At Full Charge, Study Finds

 

[commadorebob]

Using my current driving habits, I will let it discharge to about 20% before plugging it into a 110V charger. As I work from home, I really don't care if it takes a day and a half to charge. If I'm planning to travel with it, then I'll let it get to 100% in advance. In principle, I tend not to keep batteries fully charged on my devices. I keep my Ryobi batteries at 50% until I actually need them.

 

[chl]

Numbers differ about charge cycles to 80% capacity.

For LFP, 8,000 is an outside number, usually more realistically 5,000-6,000.
And I've always heard at least 2,000 cycles as the number for NMC not 1500.

The empirical real-life studies I've have seen say up to as many as 3,000 cycles depending.

For LFP's the lifespan in cycles seems to be highly dependent on depth of discharge/charge the deeper the discharge/charge, the shorter the lifespan.

I think all things considered, keeping the Fathom LFP battery healthy will be a bit more complicated than the Lightning with an NMC battery. Needing to charge it to 100% periodically but not keeping it above 75% most of the time will take some getting used to for me anyway.

NMC's can do 2,000 cycles then LFP could easily do 3 times that or about 6,000 cycles before reaching the 80% capacity threshold provided all the recommendations about charging are followed.

Age alone is probably going to take between 1% and 4% capacity per year what ever Li battery type.
Some of the estimates have proven too pessimistic and in real life use they last longer than predicted.

Both NMC and LFP probably have an 80% lifetime of 10 to 20 years depending on other factors, like depth of discharge (DOD) and the number of times they are subjected to high charge rates (DC fast charging).

https://www.anernstore.com/blogs/diy-solar-guides/lifepo4-battery-lifespan-performance

One potential drawback for the LFP may be performance in cold weather, they do not perform as well as NMC. So we might expect the Fathom to be using quite a bit of energy to warm the battery in cold weather/climates.

I have read that LFP batteries absolutely require preconditioning before fast charging in cold weather to avoid battery damage (plating), so out on the road this means more energy will be used to warm the battery than with an NMC, which will take off a bit more off the range.

On the other hand, LFP batteries are a lot safer from thermal runaway and fires, etc., than NMC.

For the battery upgrade in the Fathom I would not be surprised if they use NMC batteries because they can pack in more energy in the same space and weigh less than LFP per unit volume. Also NMC will charge faster at a higher rate (DC current) than LFP, though they currently cost more per kWh capacity.