The SK ON E777 is a 77.7 Ah NMC pouch cell built to automotive standards, and in our range it is the power-focused option rather than the capacity-at-any-cost one. Nominal voltage is 3.65 V, and the cell is engineered for sustained current rather than for a headline capacity figure alone.
The soft-pack body is what makes the format usable inside a real enclosure. There is no steel or aluminium can taking up volume, cells sit directly against one another in a stack, and heat has a short path out of the electrode stack instead of being trapped behind a rigid shell. When the enclosure is thin and the load is heavy, that is the combination that counts.
The cathode is nickel manganese cobalt, and catalogues do not agree on how to write it. We list the product as an NMC pouch cell. Some specification sheets and purchase systems call the same chemistry an NCM pouch cell, and if your documents use the second form the cell itself is unchanged.
We quote this model next to a comparable Farasis battery pouch cell and other branded options, so a project can be compared cell for cell on one quotation instead of across three suppliers' PDFs. Send the pack voltage, the continuous current you need and the depth available in your enclosure, and the answer will be specific to your build.
| Battery model | SK-77.7 (E777) |
| Cell type | NMC pouch cell |
| Nominal voltage | 3.65 V |
| Nominal capacity | 77.7 Ah |
| Working voltage range | 2.0–4.3 V |
| Max charge current | 0.5C |
| Max continuous discharge current | 1C |
| Peak discharge current | 5.15C |
| Internal resistance | ≤1.06 mΩ |
| Charge, discharge and storage temperature | -30 to 60 °C |
| Cycle life | ≥1000 cycles |
| Dimensions (length × thickness × width) | 530 × 8.6 × 99.7 mm |
| Weight | 1.07 kg |
| Warranty | 2 years |
Against LiFePO4. An NMC cell stores more energy per kilogram, so a pack built on this chemistry is lighter and smaller for the same usable capacity; an LFP pack of equal capacity is bulkier and heavier. LFP still wins on cycle life, where its chemistry is good for several thousand deep cycles against a rating a good deal lower here, and it carries more thermal and structural safety margin, because iron phosphate is harder to drive into runaway. NMC gives back cold-weather performance: the cell keeps a useful share of its output below freezing, where an LFP pack loses a large part of its own. That split is why an NMC pouch cell tends to land in consumer products, light EVs and traction packs, while LFP dominates stationary storage and heavy cycling.
Against prismatic NMC. The cathode is the same; the packaging is not. A prismatic cell sits in a metal can with a fixed shape — it shrugs off impact and generally delivers a longer cycle life, but it handles internal pressure less gracefully. A pouch cell is a soft laminate: thinner, lighter, able to take a shape that follows your enclosure, and better at relieving pressure if a cell does vent. Prismatic suits racks and structural packs where the can is part of the frame; pouch suits portable products, light mobility and any design where depth is the constraint.
Why builders pick this format. Energy density comes first: more capacity in a smaller, lighter body means longer runtime at the same pack weight. The flexible form factor comes second — the cell is thin enough to be stacked and shaped around a slim product. Space utilisation is third: soft-pack cells fill a module with almost no dead volume between them. Fit is fourth: lightweight portable equipment and light mobility are exactly where the format pays off.
What that means when you buy. The NMC battery manufacturers who supply this class of cell work to tighter process tolerances than LFP producers, because the chemistry is less forgiving of contamination and moisture. We quote this cell beside a Farasis battery pouch model and other branded options, and we will say plainly when a different chemistry is the better answer for a stationary job — a specification that fits the duty cycle is worth more than a cell that merely wins on paper.
A pack is only as tolerant as the cell inside it, and this one is rated across the same temperature range for charging, discharging and storage — one envelope to configure rather than three. That simplifies the BMS considerably: the limits you set for protection are the same limits you set for the charger.
Cold is mostly a charging problem. Discharge is the forgiving direction; putting current back into a cold cell is not, and it is the single most common cause of the failures that reach us as a lithium battery supplier. Most pack designs inhibit charge while the cells are cold, or bring a heater on first and wait, rather than pushing current into a frozen cell. If your product parks outdoors in winter, plan that heater into the pack from the beginning rather than adding it after the first field complaint.
At the top of the range the cell still works, but cycle life shortens as average temperature climbs, so a pack that lives under a hot roof or beside an inverter should be derated or actively cooled. Sensor placement matters as much as cooling: put NTCs against the faces of cells in the middle of a stack, not on the end plates, because the centre runs hottest while the ends read a comfortable number.
Thermal interface material and even spacing do the rest. A pouch cell battery has a large flat face, which is an advantage — it gives you somewhere to conduct heat out — provided the module actually presses the cell against that surface instead of leaving an air gap.
Repeat orders are the clearest feedback we get, and the reasons buyers come back are practical rather than dramatic. Pack builders tell us they stop re-measuring thickness after the first delivery — a soft-pack that varies in thickness throws out the stack height of a whole module, so once a batch stacks predictably the incoming check gets shorter. Others mention that voltage and resistance readings on arrival land inside the band they set for series assembly, which is the part that decides how many cells can be grouped before balancing becomes a chore.
Paperwork is the third theme. Test reports and transport documents that arrive with the cells, rather than weeks after the container is booked, save a surprising amount of chasing. When a buyer compares one NMC pouch cell supplier with another, this is usually where the difference shows up — not in the headline capacity figure.
We also hear from engineers who want to change a module design mid-project. That is a conversation worth having early: send the new stack height or terminal layout and we will check whether this cell or a different pouch format suits it better. If your other product lines already run a Farasis battery model, we can put both on one quotation so the comparison is at least like for like.
How long it lasts in your duty cycle
The ≥1000-cycle figure is a standard-condition rating — a floor measured at a steady temperature and a defined depth of discharge, not a prediction for your pack. What moves the number in service is depth of discharge, average temperature and charge rate. Shallow cycles at moderate temperature go further than a full daily swing inside a hot enclosure, and heat is the accelerant that matters most: a pack that lives under a hot roof or beside an inverter reaches its cycle limit sooner in calendar terms than one that runs cool.
Turn the rating into a replacement interval. One full cycle a day is about 365 cycles a year, so the ≥1000-cycle floor corresponds to roughly three years of daily full cycles before the cell reaches its rated end. Most packs are retired at a percentage of original capacity rather than at hard failure, so fix that end-of-life figure before you build, then size the reserve behind it: the two-year warranty is a calendar commitment, and the replacement budget should come from cycles per year multiplied by the duty you actually run, not from the headline on the datasheet. Tell us cycles per day, depth of discharge and average ambient, and we will say whether this cell is working inside its comfort zone or whether a longer-life chemistry suits the job better.
Storing cells between builds
Keep cells in the original packaging, in a dry ventilated space inside the storage range shown in the specifications, out of direct sun and away from heat sources. That range is a limit, not a target — stock held at the top of it ages faster than stock kept near room temperature. After cold transport, let sealed cartons come back to room temperature before you open them, so condensation does not form on the tabs. If stock will sit for months rather than weeks, ask us for the storage voltage we recommend for this model before you top anything up, and check open-circuit voltage on a sample at intervals. Rotate stock so the oldest batch is built first, write the batch and receipt date on the carton, and never stack heavy cartons on cells or store them where loose metal can bridge the tabs.
Every order is checked before it leaves us. In-depth partnerships with CATL, CALB, EVE, Farasis and other leading manufacturers give us traceable, original-brand cells, and our team runs a full inspection pass on every shipment, with sampling checks on packaging and labels. Anything that fails is held back, replaced and reported to you before dispatch. You are welcome to send your own inspector or appoint a third-party agency; we arrange access, samples and the documents they need, and the same paperwork travels with the goods.
Only when the model, chemistry and capacity match. Within the same model, mixing batches is common in pack building, but match the groups on measured voltage and internal resistance before you assemble a series string so the BMS starts from a consistent baseline. Never put this cell in series with a different chemistry or a different capacity — the weaker group sets the limit for the whole string, and the mismatch shows up as heat rather than as an obvious fault.
The cycle-life figure in the specifications is a floor measured under standard test conditions, not a prediction for your pack. Real life depends on depth of discharge, average temperature and charge rate: shallow cycles at moderate temperature go considerably further than a full daily swing in a hot enclosure. Decide early what end-of-life means for your application — most packs are retired at a percentage of original capacity rather than at a hard failure — and size the pack so the cell is not working at its limit every day.
Yes. Both names describe a cathode of nickel, manganese and cobalt; the letter order follows different conventions in different markets and data systems. We use NMC on our own documents, and if your specification or purchase order says ncm pouch cell, it refers to the same chemistry in the same soft-pack format. Check that the other parameters still match — capacity, voltage and dimensions are what actually decide whether a cell fits your design.
Keep them in the original packaging in a dry, ventilated space inside the storage range shown in the specifications, out of direct sun and away from heat sources. If cells move from a cold truck into a warm room, let them reach room temperature while still sealed before opening, so condensation does not form on the tabs. Check open-circuit voltage on a sample if stock sits for a long period, and rotate stock so the oldest batch is built first.
The cell is a soft pack, so thickness is the dimension that decides whether a stack fits: compare the nominal figure against your frame with the clamping your design uses, not against a bare cell on a bench. Tab position, terminal orientation and the allowance you leave for swelling over life matter as much as length and width. Send us the module drawing and we will check it against the cell drawing before you commit to a batch.
