LiFePO4 vs NMC batteries in power stations: cycles, weight and heat

Buy a station with a LiFePO4 battery. The current 1kWh stations from EcoFlow, Jackery and Bluetti all use it and are rated for around 4,000 cycles, while Jackery's older NMC Explorer 1000 was rated for 500. The weight penalty LiFePO4 used to carry has mostly gone at this size, and fire researchers rate it as the more stable chemistry when something goes wrong.

The figures below come from the makers' Australian pages and manuals, and the safety material from Fire and Rescue NSW and the Queensland Fire Department. All are linked at the bottom. We haven't run cycle tests ourselves, so treat the cycle numbers as the makers' ratings.

What the two names mean

Both are lithium-ion. The difference is the material in the positive electrode. LiFePO4 is lithium iron phosphate, often shortened to LFP; EcoFlow calls it LFP and Jackery and Bluetti call it LiFePO4, but it's the same thing. NMC is nickel manganese cobalt (Jackery's own spec page writes it NCM).

NMC packs more energy into each cell, which is why phones, laptops and most early power stations used it. LiFePO4 stores a bit less per cell but puts up with far more charging cycles, and it doesn't contain nickel or cobalt. Nearly every new power station sold here now uses it, so NMC mostly turns up on older models and second-hand listings.

Cycle ratings, side by side

A cycle is one full charge and discharge, or two half ones. Makers quote how many cycles it takes before the battery drops to a stated share of its original capacity. Watch that end point, because it isn't the same everywhere.

EcoFlow's 4,000 cycles to 80% is a tougher promise than Jackery's 4,000 cycles to 70%, even though the headline number matches. Bluetti's Australian page says over 4,000 cycles without giving an end point. The EcoFlow vs Bluetti vs Anker SOLIX comparison has the rest of the specs for these three, plus the Anker SOLIX C1000.

What that means in years

How long the battery lasts depends on how often you cycle it. For blackout backup you might run it flat once a week through storm season and barely touch it the rest of the year. Living in a caravan, you could cycle it every day.

Say you cycle it every day. 500 cycles / 365 = about 1.4 years before an NMC Explorer 1000 reaches 80% of its capacity. 4,000 cycles / 365 = about 11 years for a LiFePO4 station. Once a week, the NMC unit would take 500 / 52 = about 9.6 years to use up its rating, and other ageing would probably catch it first.

It also helps to know what's left at the end. A new Explorer 1000 v2 gives roughly 1,070 x 0.85 = 910Wh after inverter losses, which runs a fridge averaging 60W for about 910 / 60 = 15 hours. At 70% capacity that becomes 1,070 x 0.7 x 0.85 = 637Wh, or about 10.6 hours. The 0.85 is our allowance for conversion losses and the 60W fridge is an example, so plug in your own numbers with the runtime calculator.

The weight gap has closed

LiFePO4's reputation for being heavy comes from the cells. At the whole-station level, at around 1kWh, it barely shows any more. Jackery lists the original NMC Explorer 1000 at 1,002Wh and about 10.6kg on its support site (its older spec sheet says 10kg). The LiFePO4 Explorer 1000 v2 is 1,070Wh and 10.8kg.

Work it per kilo and the new one comes out slightly ahead: 1,070 / 10.8 = about 99Wh per kg, against 1,002 / 10.6 = about 95Wh per kg. The case, inverter and cooling make up a lot of a power station's weight, and those have improved too. The EcoFlow DELTA 3 Plus is heavier, at up to 12.5kg, but it carries a bigger inverter and takes extra batteries. If you're lugging it to a campsite, the caravan and camper sizing guide goes through how much battery you actually need.

Heat and what happens in a fault

A Fire and Rescue NSW research review of lithium-ion safety says chemistries with more nickel hold more energy but are less thermally stable, and that LiFePO4 shows the reverse. Studies it summarises found NMC cells in thermal runaway peaking at 555 to 1,066°C, against 357 to 525°C for LiFePO4, and heating much faster.

The same review adds two caveats. LiFePO4 cells tend to release more hydrogen when they fail, and their gases can be more toxic. So a LiFePO4 station is less likely to go up violently, not safe to treat carelessly. The Queensland Fire Department's advice applies to both: charge on a hard, non-combustible surface in a ventilated spot, don't leave it charging unattended, don't use a battery that's hot, swollen or damaged, and keep stored batteries away from heat and direct sun.

Day to day, the station's limits matter more than the chemistry. Jackery's Australian manual gives 0 to 45°C for charging the Explorer 1000 v2, while its support site lists 0 to 40°C for the original NMC Explorer 1000. Either way, a closed car in a Queensland summer can go well past that, so don't leave any station in one.

When NMC still makes sense

If you already own a working NMC station, keep using it. Ten years of light blackout duty is well within 500 cycles. Just store it the way the maker says, check it before storm season, and replace it if it swells, gets hot or the run time drops away.

We wouldn't buy one now, new or second-hand. A used NMC unit has an unknown number of cycles behind it and a short rating to start with. If a listing doesn't say the chemistry, look up the model on the maker's site before you pay. When it's time to get rid of an old one, the Queensland Fire Department says to tape the terminals, keep it out of household bins and ask your council or a battery recycling scheme like B-cycle where to take it. For what a home kit should look like, see the blackout and cyclone season guide.

Where to buy in Australia

Buying from the brand's Australian store means 230V AU outlets, the local warranty and local support. Prices move around a lot, so check on the day.

• EcoFlow DELTA 3 Plus (1,024Wh LFP)EcoFlow AustraliaSee it at EcoFlow Australia
• Jackery Explorer 1000 v2 (1,070Wh LiFePO4)Jackery AustraliaSee it at Jackery Australia
• Bluetti Elite 100 V2 (1,024Wh LiFePO4)Bluetti AustraliaSee it at Bluetti Australia