Lithium-Ion Batteries for Gadgets: Power Banks, Laptops & Drones

Quick answer

Gadget batteries are small, lightweight lithium-ion (NMC) or lithium-polymer (LiPo) packs built from 3.6–3.7V cells. Power banks usually use single-cell-voltage packs; laptops use 3-cell (11.1V) or 4-cell (14.8V) series packs; drones use high-discharge packs rated by C-rating. The right battery matches the device's voltage, capacity, discharge current and connector.

Gadget battery terms explained

mAh: Milliamp-hours: charge capacity at the pack's own voltage. Only comparable between packs of the same voltage.
Wh: Watt-hours: true energy. Wh = mAh × V ÷ 1000. A 20,000 mAh power bank at 3.7V holds about 74 Wh.
S (series): Number of cells in series. 3S = 3 × 3.7V = 11.1V nominal; 4S = 14.8V.
P (parallel): Cell groups in parallel to add capacity and current without changing voltage.
C-rating: Discharge current as a multiple of capacity. A 5,000 mAh pack at 20C can deliver about 100 A.
BMS / PCM: Protection circuit guarding against overcharge, over-discharge, over-current and short circuit.

Power bank batteries

A power bank is a lithium cell pack plus a charging and boost circuit that converts cell voltage to USB output. In Pakistan, power banks are widely used as personal backup for phones, routers and laptops during load shedding.

Portable power banks use case

Cells: typically 18650/21700 cylindrical Li-ion or flat Li-polymer pouches, at 3.6–3.7V nominal
Capacity is advertised in mAh at cell voltage; real output at 5V/9V/20V USB is lower because of conversion losses
Laptop charging needs USB-C Power Delivery at an adequate wattage, not just high mAh
Air travel: power banks up to 100 Wh are generally allowed in cabin baggage, subject to airline rules

Laptop batteries

Laptop batteries are series packs — most commonly 3S (11.1V nominal) or 4S (14.8V nominal) — with an integrated protection and fuel-gauge circuit that communicates with the laptop.

Batteries by voltage

Voltage and cell count must match the original pack; capacity (Wh) can vary
Many laptops need the pack's gauge chip to report correctly before they will charge
Heat is the main cause of capacity loss — keep vents clear and avoid charging in hot enclosures
Rebuilding or custom packs require matched cells of the same model and state of health

Drone batteries

Drones need high power in a light package. Packs are chosen for discharge rate (C-rating) as much as capacity, because take-off and manoeuvres draw peak current.

Custom & industrial batteries

LiPo packs give very high discharge rates for racing and FPV; Li-ion packs trade peak power for longer flight time
Common configurations run from 3S (11.1V) to 6S (22.2V) and above, matched to the motors and ESC
Pack weight directly reduces flight time and payload — more capacity is not always better
Store LiPo and Li-ion packs at storage voltage and never fly a swollen pack

Custom portable packs

Cameras, lighting, handheld instruments, robotics kits and other portable devices often need a pack in a specific shape, voltage or connector. AmpereX builds lithium-ion packs from standard cell configurations to match the device.

Battery services

Designed from the device's voltage, current draw, runtime and available space
Protection circuit (BMS) sized for the device's peak current
Connectors, leads and enclosure matched to the device

Cell chemistries used in gadget batteries

Lithium cell chemistries for gadgets compared
Chemistry / format	Nominal cell voltage	Typical devices	Characteristics
Li-ion (NMC) cylindrical — 18650 / 21700	3.6–3.7V	Power banks, laptops, long-range drones	Robust casing, good energy density
Li-polymer (LiPo) pouch	3.7V	Slim power banks, phones, racing drones	Thin shapes, very high discharge; needs physical protection
LiFePO4	3.2V	Portable power stations, larger portable packs	Long cycle life and stability; heavier for the same energy

11.1V lithium-ion packs & protection

3S lithium-ion packs, BMS and monitoring products from the AmpereX catalogue, used in laptops, drones and custom portable devices.

Gadget batteries: frequently asked questions

What battery is used in power banks?

Most power banks use lithium-ion 18650 or 21700 cylindrical cells or lithium-polymer pouch cells, at 3.6–3.7V nominal, with a circuit that boosts the voltage to USB output.

How do I convert mAh to Wh?

Multiply mAh by the nominal voltage and divide by 1,000. For example, a 20,000 mAh power bank with 3.7V cells stores about 74 Wh.

What voltage are laptop batteries?

Most laptop batteries are 3-cell series packs at 11.1V nominal (3S) or 4-cell packs at 14.8V nominal (4S). The replacement must match the original voltage and cell count.

What is C-rating in drone batteries?

C-rating is the maximum discharge current as a multiple of capacity. A 5,000 mAh (5 Ah) pack rated 20C can deliver about 100 A. Drones need enough C-rating for take-off and manoeuvring current.

LiPo or Li-ion for drones?

LiPo delivers higher peak current for racing and aggressive flying. Li-ion packs are usually lighter for the same energy at moderate current, giving longer flight times for cruising and mapping drones.

Can AmpereX make a custom lithium-ion pack for my device?

Yes. AmpereX builds custom lithium-ion packs from standard cell configurations, designed around the device's voltage, current draw, runtime, available space and connector.

Lithium-Ion Batteries for Gadgets: Power Banks, Laptops & Drones

Quick answer

Gadget battery terms explained

mAh

Milliamp-hours: charge capacity at the pack's own voltage. Only comparable between packs of the same voltage.

Watt-hours: true energy. Wh = mAh × V ÷ 1000. A 20,000 mAh power bank at 3.7V holds about 74 Wh.

S (series)

Number of cells in series. 3S = 3 × 3.7V = 11.1V nominal; 4S = 14.8V.

P (parallel)

Cell groups in parallel to add capacity and current without changing voltage.

C-rating

Discharge current as a multiple of capacity. A 5,000 mAh pack at 20C can deliver about 100 A.

BMS / PCM

Protection circuit guarding against overcharge, over-discharge, over-current and short circuit.

Cell chemistries used in gadget batteries

Lithium cell chemistries for gadgets compared
Chemistry / format	Nominal cell voltage	Typical devices	Characteristics
Li-ion (NMC) cylindrical — 18650 / 21700	3.6–3.7V	Power banks, laptops, long-range drones	Robust casing, good energy density
Li-polymer (LiPo) pouch	3.7V	Slim power banks, phones, racing drones	Thin shapes, very high discharge; needs physical protection
LiFePO4	3.2V	Portable power stations, larger portable packs	Long cycle life and stability; heavier for the same energy

Gadget batteries: frequently asked questions