The CE-1865 is a 3.2V 18650 LiFePO4 cell, 1.8 amp-hours, 5.76 watt-hours. It shares the 18mm by 65mm size of the common lithium cylindrical cell, but runs the phosphate chemistry rather than NMC. That choice trades energy density for safety and cycle life, which is the right trade for the jobs this cell is built for.
LFP vs NMC
The 18650 choice, in numbers
An 18650 comes in two main chemistries and the difference is measurable. An NMC cell runs 3.6 to 3.7 volts nominal and packs more energy; an LFP 18650 runs 3.2 volts and holds less. What LFP gives back is a thermal runaway threshold near 280°C against about 150°C for NMC, less than a third of the heat released if it does fail, and a cycle life above 2,500 charges against roughly 1,000 for NMC. For a device that must sit charged for years and stay safe, those are the figures that decide it.
The flat discharge is the second reason. An LFP cell holds close to 3.2 volts across most of its charge, where an NMC cell swings from 4.2 down to 2.8. Instruments and lighting drivers designed around a steady rail run cleaner on the flatter curve.
Where It Fits
The jobs that want LFP small
Emergency lighting is the clearest case. A luminaire holds its battery charged for years and must light on demand without a fire risk in a ceiling void, which is exactly the safety-and-longevity profile LFP wins. The same logic covers instrument backup, metering, alarm panels, small solar lamps and any pack that sits charged more than it cycles. Four cells in series make a 12.8V pack that a standard charger handles.
Data
Datasheet
| Model | CE-1865 (18650) |
|---|---|
| Nominal voltage | 3.2V |
| Rated capacity | 1.8Ah |
| Energy | 5.76Wh |
| Charge voltage | 3.65V |
| Discharge cutoff | 2.0V |
| Continuous discharge | 5.4A (3C) |
| Peak discharge | 9A (5C) |
| Cycle life | ≥2,000 cycles |
| Weight | ≈45 g |
| Size | 18 × 65 mm |
| Operating temperature | Discharge -20~60°C / Charge 0~45°C |
| Certification | UN38.3 / CE / RoHS |
Pack notes
| 4S | 12.8V · 23Wh: instrument and lamp packs |
|---|---|
| 4S2P | 12.8V · 46Wh: longer-runtime backup |
| High-rate | 3C continuous for pulse loads |
Reading a small LFP spec
Two numbers on the datasheet decide whether an 18650 LFP suits a job. The first is the discharge rate: a high-rate 18650 delivers several C, which for a 1.8-amp-hour cell is a handful of amps continuous, enough for the small motors and drivers these packs run. The second is the temperature window, minus twenty to sixty on discharge and above freezing on charge, which covers a lit corridor or a sealed instrument box but calls for a heater on an outdoor unit that sees frost. Beyond those, the flat voltage and the long cycle life are what make the cell worth its lower energy density in a standby role. A device that cycles once a day for a decade, or sits charged and waiting, gets more life from LFP than from a higher-energy NMC cell that wears out in a third the cycles.
Build
Assembling a small pack
Small cylindrical cells are usually spot-welded into a pack with a nickel strip and a matching BMS, not bolted. Match cells on capacity and internal resistance before welding, which the factory batch already does for cells from one lot. Charge to 3.65 volts per cell and stop discharge near 2.5. A pack that sits on standby holds at 30 to 50 percent charge and loses only a few percent a month. Every cell traces to its factory test record.
Storage and handling follow the small-cell rules. These cells ship at a partial charge for transport, rest at 30 to 50 percent on standby, and lose only a few percent a month while they wait. Because a welded pack cannot be opened to swap one cell, the matching that happens at the factory batch is what keeps a multi-cell pack even over its life, and it is why an emergency-lighting or metering pack built from one lot ages as a unit rather than failing a cell at a time. Delivered capacity meets the 1.8-amp-hour rating on a standard-rate test.
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