Two LR2170SZ cells sit side by side inside a flat, PVC-wrapped body, making this a 7.2V battery pack for compact devices with roughly 36Wh of energy in a shape that slips into shallow equipment bays. It was built for the product where the battery compartment comes last — a handset, a lamp handle, a control box with the board stacked above the power section — rather than for a device with room for a cylindrical tube.
Capacity is rated at 5Ah on a C5 discharge, with every unit carrying a 4.5Ah minimum, so runtime planning can be done against the conservative figure. The 2S1P arrangement keeps the build simple: two cells in series, one parallel string, one protection board and a single lead exit.
That single 8-pin plug carries everything the device needs — positive and negative power leads, a voltage-sensing wire and an NTC thermistor. One cable assembly to route and strain-relieve instead of two, and the controller can watch pack voltage and cell temperature while the product is running.
Every order is a custom lithium battery pack rather than a catalogue item, so the values here are a starting configuration. Wire length, connector type, protection thresholds, wrapping and even the cell count are revisited once your compartment drawing and load profile are on the table.
| Parameter | Specification |
|---|---|
| Nominal voltage | 7.2V |
| Rated capacity | 5Ah (C5) |
| Minimum capacity | 4.5Ah (C5) |
| Rated energy | Approx. 36Wh |
| Cell configuration | LR2170SZ-2S1P |
| AC internal resistance | ≤100mΩ |
| Charging voltage | 8.3-8.4V |
| Standard charging current | 1A |
| Maximum charging current | 2.5A |
| Charge cut-off current | 50-100mA |
| Standard discharge current | 1A |
| Maximum continuous discharge current | 1.5A |
| End-of-discharge voltage | Approx. 5.6V |
| Charge retention | ≥85% after 28 days |
| Cycle life | ≥700 cycles, with ≥70% capacity retention |
Charge the 7.2V 5Ah compact NCM battery from a dedicated lithium-ion CC/CV charger set to the pack's charging voltage. The standard 1A rate is the comfortable default for overnight charging or a break between shifts; the higher maximum allows a faster charger to work, but only when it holds the profile correctly and the enclosure has somewhere for the heat to go.
Termination matters as much as current. The pack stops accepting charge at the cut-off current in the table, which is how a CC/CV charger knows the cells are full. A plain constant-voltage supply with no termination window keeps trickling current in and shortens the pack's life, and chargers built for another chemistry are a frequent cause of early failure in sealed products.
On discharge, treat the maximum continuous rating as the working limit and the standard rating as the point where the pack runs most comfortably. Sensing, lighting and control electronics sit inside the standard rating without stress. Anything with a motor, solenoid or heater pulls a start-up pulse well above its running current, and that pulse is what has to be checked against the pack before the design is fixed; low internal resistance keeps voltage sag modest on short bursts, but average current is what drives heat and cycle life.
End of discharge is a device decision too. The pack's voltage falls away quickly once it passes the end-of-discharge point, and a product that keeps pulling power past it will trip the protection cut-out without warning. Set the low-voltage warning a little above the protection threshold so the user sees the warning before the device stops.
Temperature settles the rest. Charging is only allowed inside the narrow window in the specification, while discharge is permitted across a much wider range — sensible for equipment that works outdoors but is charged indoors. A pack that has spent the night in a cold vehicle should be allowed to reach room temperature before charging starts.
| Item | Specification |
|---|---|
| Packaging | PVC |
| Dimensions | Approx. 71 × 25 × 15mm |
| Weight | 150±20g |
| Series wire length | 40±5mm |
| Connector | DF51K-8DS-2C (800) plug wire |
| Wire specification | 24AWG, 115±5mm |
| Wire definition | Red: positive; black: negative; yellow: voltage sensing; white: NTC |
| Charging temperature | 5°C to 45°C |
| Discharging temperature | -20°C to 55°C |
This pack sits inside a family of NCM lithium-ion packs that runs from single-cell 3.6V builds through 10.8V designs up to multi-cell packs in the 25.2V class. NCM chemistry is chosen when energy has to fit a small volume: it stores more watt-hours per litre than lithium iron phosphate, which is why a 36Wh pack can be this thin.
Within that range, a two-cell series string is a common rail for handheld instruments, lighting drivers and control electronics, and it is the simplest way to reach that intermediate voltage. When a project needs more runtime at the same voltage, the parallel count goes up rather than the series count, so the rail stays exactly where the device expects it.
Buyers usually arrive with three questions: does the shape fit, does the connector match, and is the current rating enough. The range answers all three by treating the listed build as a reference — the chemistry class and voltage stay, while the mechanical and electrical interface is set for the device.
LiFePO4 versions exist where cycle life and thermal stability matter more than volume, so a project that starts on NCM can be re-examined on the other chemistry if the runtime requirement grows. The fair comparison is always at the same load, the same charger and the same compartment.
Because every order is a custom lithium battery pack, the build is agreed rather than picked off a shelf. On the electrical side the variables are cell count, capacity and protection thresholds: a 2S1P build can move to a parallel pair for more runtime at the same 7.2V, and the overcharge, over-discharge and temperature limits are set to your device's own cut-offs instead of a generic default.
Mechanically, the pack can be built to different dimensions within what the cell format allows, with a different PVC wrap colour or structure, a mounting or fixing structure, and labels carrying your part number and your own warning text.
The interface is where most projects actually differ. The DF51K plug is the standard fit, but it can be changed for the connector already on your board, and the cable length, wire gauge, and the way the NTC and voltage-sensing leads are terminated all follow your drawing.
Protection design belongs in the same conversation: which functions the board must include, at what thresholds, and how it should behave when the product sits idle for weeks. All of it is settled before a sample is built, so the unit you test reflects the configuration you will order.
Sample builds follow an approved drawing. Once the configuration, the drawing and the specification revision are agreed, ask your sales contact about sample availability and the current schedule for the build you need.
Lead time depends on the cell batch, the connector and the protection board, so confirm the present figure for samples and for production quantities rather than working from an earlier estimate. If the project has a launch date, share it at the enquiry stage so the schedule can be planned around it.
Lithium packs are dangerous goods for transport. Ask which documents are available for the exact configuration you order — transport paperwork, test reports and any market-specific requirements your customers raise — and check that they cover the revision you are buying, since a report issued for a different pack does not cover yours.
Packing follows the lead and connector arrangement of the build so the terminals arrive protected. Confirm the carton quantity, labelling and any pallet or shipping marks you need when the order is placed, and settle payment terms, packing configuration and delivery arrangements with your sales contact alongside the quotation.
Technical questions reach the people who build the packs. Our engineering group in Shenzhen reviews your device's voltage window, load profile, enclosure space and charger before proposing a configuration; our sample group then builds units so you can validate fit and runtime before production. Cell selection, BMS design and pack assembly stay in-house, with quality checks in process and at final inspection, and a documentation team handling certificates, test reports and shipping papers. When a unit behaves unexpectedly in the field, our engineers help trace the fault and advise on installation and commissioning.
Only after the electrical and mechanical fit has been checked. A replacement is rarely a straight swap on voltage alone: compare the compartment drawing, the connector type and pinout, the charger profile and the actual load current first. Because the connector, wiring and protection can be changed, a replacement build usually starts from the existing cable assembly you already have rather than from the plug we fit as standard.
Rated capacity is what the pack delivers in the standard C5 test; the minimum is the floor every unit must reach before it leaves the line. Plan runtime against the minimum figure and let the rated value be the typical result — that way a device that just meets its target on paper still meets it in the field. This 7.2V 5Ah compact NCM battery is rated at 5Ah with a 4.5Ah minimum for exactly that reason.
Red is positive, black is negative, yellow carries voltage sensing and white connects the NTC thermistor. The sensing pair lets the device read pack voltage and cell temperature directly instead of inferring them from the supply rail. If your board has no use for them, the sensing leads can be left out of a custom build — tell us at the brief stage so the connector and pin count match your design.
It depends on the motor's start-up behaviour rather than its running current. The pack's continuous rating suits steady sensing, lighting and control loads. Motors, pumps, solenoids and heaters pull a pulse several times their running current for a short time, so send the start-up curve and pulse duration with your enquiry and we will tell you whether this configuration holds it or whether a different parallel count is needed.
Through a proper CC/CV charger at the pack's charging voltage, ending at the specified cut-off current. If the device charges the pack from its own circuit, review that circuit's voltage accuracy, current limit and termination with our engineers before release — a supply that never terminates is the most common way a sealed pack loses capacity early. Charging outside the temperature window in the specification should be blocked by the device.
The standard build uses a DF51K-8DS-2C (800) plug wire on 24AWG leads, with the four-wire definition above. To change it, send the mating half's part number or drawing, the pinout, the polarity order you expect and the cable length you need. That is enough for this custom lithium battery pack to be built around the connector you already use.
Charge retention is at least 85% after 28 days, so a pack stored for a month still arrives with useful energy. For longer stock periods, confirm the storage state of charge and the recharge interval for your build with us, and keep storage inside the temperature limits — a pack that has been stored cold should be allowed to warm before charging.
