Glossary of batteries and portable power

The ampere is the unit of electric current, that is the flow of charge passing through a conductor. The higher the amperage, the larger the current delivered. On a battery or a charger, it governs both charging speed and available power, following the relation power equals voltage multiplied by current.

The amp-hour expresses the charge a battery can deliver for one hour at a current of one ampere. It is a capacity measure used mainly for lead-acid batteries and rechargeable cells. One amp-hour equals 1000 milliamp-hours. To compare batteries of different voltages, watt-hours are more reliable.

Runtime is how long a battery powers a device before running flat. It depends on the usable capacity (in watt-hours), the load's consumption and conversion efficiency. The same battery therefore offers very different runtimes depending on what you plug in, from a smartphone to a fridge.

Capacity is the amount of energy a battery can store, expressed in watt-hours (Wh) or amp-hours (Ah). It is the central figure for estimating how many times you can recharge a device. Note that the capacity quoted at cell level is always higher than the energy actually delivered at the output, because of losses.

Alternating current is a current whose direction reverses periodically. It is the current of the domestic mains, 230 volts at 50 hertz in Europe. Portable power stations produce it from their battery through an inverter, to run appliances that plug into a wall socket.

Direct current always flows in the same direction. It is the current supplied by batteries, solar panels and USB ports. Most portable devices run on DC, often at 5 volts (USB), 12 volts (car socket) or 20 volts. Converting DC to AC requires an inverter.

Power factor is the ratio between the real, useful power (in watts) and the apparent power (in volt-amperes) of an AC device. A factor close to 1 is ideal. Motor and pump appliances often have a lower factor, which puts more strain on a power station's inverter.

Impedance is the total opposition a circuit offers to alternating current, measured in ohms. Applied to a battery, low internal impedance lets it deliver high currents without a noticeable voltage drop or excessive heating, a sign of good health and quality.

The kilowatt is a unit of power equal to one thousand watts. It is used for hungry appliances such as heaters, hobs or power tools, and for the output power of large power stations and portable generators.

The kilowatt-hour is a unit of energy equal to a one thousand watt appliance running for one hour. It is the unit on your electricity bill. One kilowatt-hour equals one thousand watt-hours. Large home batteries and the highest-capacity power stations are measured in kilowatt-hours.

The milliamp-hour is a subunit of the amp-hour (one thousand mAh make one Ah). It is the capacity figure shown on power banks and small batteries. It only means something alongside a voltage: 10000 mAh at 3.7 volts equals about 37 watt-hours once converted.

Peak power is the maximum power a power station or inverter can deliver very briefly, typically when a device starts up (the inrush of a fridge or tool motor). It is well above the continuous power and is often listed separately in the specifications.

Continuous power is the power a station can supply indefinitely, with no time limit, expressed in watts. It determines which appliances you can run at the same time. It differs from peak power, which is only available for a few moments at start-up.

Rated power is the normal operating power quoted for a device or an output, in watts. It serves as a reference for sizing a battery or a station against the real consumption of the appliances you intend to run.

Energy efficiency is the share of stored energy actually delivered to the device, the rest being lost as heat during conversions. A power station typically shows 85 to 90 per cent. This efficiency explains much of the gap between quoted capacity and usable energy.

The volt is the unit of electrical voltage, the potential difference that sets charges in motion. It is often compared to pressure in a pipe. Common portable batteries deliver 3.7 volts at a lithium cell, 5 volts over USB, or 12 and 230 volts through an inverter.

The watt is the unit of power, the amount of energy consumed or supplied each second. It is found by multiplying voltage by current (power equals volts times amperes). It is the watt that tells you what a device can actually run, beyond capacity alone.

The watt-hour is a unit of energy equal to one watt sustained for one hour. It is the most reliable capacity measure for comparing batteries, because it factors in voltage. The 100 watt-hour threshold is also decisive for taking a battery into an aircraft cabin.

A rechargeable battery, or accumulator, can be charged again, unlike a disposable primary cell. It stores energy chemically and releases it electrically, over hundreds to thousands of cycles depending on the technology. The term covers both a lithium cell and a NiMH AA cell.

The anode is the negative electrode of a battery during discharge, the one that releases electrons into the circuit. In a lithium-ion cell it is most often made of graphite. Its makeup directly affects the cell's capacity, charging speed and lifespan.

Self-discharge is the slow loss of charge in a resting battery, with nothing plugged in. It varies by chemistry: very low for lithium (a few per cent per month), more pronounced for NiMH. A good backup battery therefore holds its charge for a long time between uses.

The BMS (Battery Management System) is the electronics that monitor and protect a lithium battery. It balances the cells, cuts off on overcharge, over-discharge, short circuit or abnormal temperature, and reports the state of charge. It is an essential safety component of power banks and power stations.

The C-rate expresses how fast a battery is charged or discharged relative to its capacity. At 1C, a 10 Ah battery delivers 10 A and empties in one hour; at 0.5C, in two hours. A high C-rate stresses the cell more and can heat it up.

The cathode is the positive electrode of a battery during discharge, the one that receives electrons. Its chemistry (NMC, NCA, LFP and so on) largely defines the cell's performance: energy density, safety, longevity and cost. It often gives the technology its name.

The cell is the basic unit of a battery, made of an anode, a cathode and an electrolyte. A battery or pack groups several cells in series and parallel to reach the wanted voltage and capacity. The 18650 and 21700 cylindrical formats are among the most common.

The 18650 and 21700 are two standard cylindrical lithium cell formats, whose names give their dimensions (18 by 65 mm, 21 by 70 mm). The newer 21700 offers more capacity. They are found in many rechargeable batteries, tools, e-bikes and power stations.

A charge cycle is one full charge and discharge of the battery, the equivalent of 100 per cent of energy renewed (two half-charges count as one cycle). Lifespan is often expressed in cycles: around 500 for a typical lithium-ion, over 3000 for LiFePO4.

A deep discharge means draining a battery very low, close to empty. It is harmful for most chemistries, especially lead, whose life it shortens sharply. LiFePO4 and deep-cycle batteries cope with it far better, which is why they are used for solar and motorhomes.

Energy density is the amount of energy stored per unit of mass or volume, in watt-hours per kilogram or per litre. The higher it is, the more compact and light the battery for a given capacity. Lithium-ion far outperforms lead, at the cost of more advanced safety electronics.

DoD (Depth of Discharge) is the percentage of capacity actually used before recharging. A DoD of 80 per cent means leaving a 20 per cent reserve. Limiting the DoD spares the battery and extends its life, a key trade-off in solar storage.

The memory effect is an apparent loss of capacity that mainly affected older NiCd batteries recharged without being emptied. The battery seemed to remember a usual discharge level. Today's lithium technologies do not suffer from it: there is no need to fully discharge them before recharging.

The electrolyte is the medium (liquid, gel or solid) that lets ions travel between anode and cathode. Its nature drives safety and performance: the liquid electrolytes of lithium cells are flammable, which is why solid-state batteries under development are so promising.

Cell balancing harmonises the charge across every cell in a pack, so none is over or under-stressed. Handled by the BMS, it maximises usable capacity and longevity. A poorly balanced pack ages prematurely, since its weakest cell limits the whole.

The state of charge, or SoC, is the energy remaining in a battery, expressed as a percentage, like a fuel gauge. It is estimated by the BMS from voltage and current. An accurate SoC readout is valuable on a power station.

The state of health, or SoH, measures a battery's ageing: the ratio of its current capacity to its original capacity. A SoH of 80 per cent indicates a 20 per cent loss, often seen as the end of useful life for a given application.

A battery pack is a set of cells assembled in series and parallel, with their BMS and enclosure. A series arrangement raises voltage, a parallel one raises capacity. Power banks, power stations and e-bike batteries are all packs, whose architecture sets voltage and capacity.

Passivation is the thin protective layer that forms on the electrode of some lithium primary cells stored for a long time. It preserves the cell but can cause a brief voltage drop on first use, until the layer clears. It is a normal phenomenon, not a fault.

Internal resistance is a battery's own opposition to current flow. Low on a fresh, quality cell, it rises with age and cold. High resistance causes voltage drops, heating and reduced output power.

Overcharge happens when current keeps being pushed into an already full battery. On a lithium cell it is dangerous (heating, risk of thermal runaway), which is why the BMS and smart chargers cut off automatically at the end of charge.

Over-discharge means draining a battery below its minimum voltage threshold. It can irreversibly damage a lithium cell and make it non-rechargeable. The BMS protects by cutting the output in time; it is also why a battery left flat for very long can become unusable.

Calendar aging is the degradation of a battery over time, regardless of use. It depends mainly on temperature and the state of charge in storage. Keeping a battery around 50 per cent charge, in a cool place, slows this natural ageing.

The lead-acid battery is the oldest and cheapest technology, used for car starting and stationary storage. Heavy and sensitive to deep discharge, it remains valued for its robustness and well-established recycling. Its AGM and EFB variants improve its endurance.

The lithium-ion battery dominates portable electronics thanks to its high energy density and low self-discharge. It covers several chemistries (NMC, NCA, LFP and so on) with different trade-offs between energy, safety and longevity. It requires a BMS to operate safely.

The lithium-polymer battery (Li-Po) is a lithium-ion variant with a gelled electrolyte, allowing thin and flexible shapes. It is found in smartphones, drones and slim power banks. It offers good energy density but remains sensitive to punctures and overcharge.

The NiCd (nickel-cadmium) battery is an old technology, rugged and cold-resistant, but penalised by the memory effect and the toxicity of cadmium. Largely replaced by NiMH and lithium, it survives only in a few specific industrial uses.

The NiMH (nickel-metal hydride) battery powers most rechargeable AA and AAA cells. Cadmium-free, more capacious than NiCd and with no real memory effect, it offers good value. Low self-discharge models keep their charge for several months.

The sodium-ion battery replaces lithium with sodium, which is abundant and cheap. Less energy-dense but very cold-tolerant and inherently safer, it is emerging for stationary storage and some power stations. It is a promising route to reduce reliance on lithium.

The solid-state battery replaces the flammable liquid electrolyte with a solid material. It promises more safety, higher energy density and faster charging. Still mostly at the development stage, it is expected to be a major breakthrough for electric mobility.

Graphene is sometimes highlighted in battery marketing. In practice there is no all-graphene consumer battery: the material is used as an additive to improve the conductivity or heat dissipation of conventional lithium cells. Treat exaggerated claims with caution.

LiFePO4 (lithium iron phosphate, or LFP) is a lithium chemistry known for its safety and very long life, often over 3000 cycles. Slightly less energy-dense, it has become the standard for power stations, solar storage and leisure batteries.

Lithium-metal uses pure lithium at the anode, which maximises energy density. It is found mostly in disposable cells (button cells, camera cells). As a rechargeable anode it remains tricky to master and is the subject of research, notably paired with solid electrolytes.

LTO (lithium titanate) replaces the graphite anode with lithium titanate. It offers very fast charging, an immense lifespan and excellent cold tolerance, but low energy density and a high cost. It targets demanding, intensive uses.

NCA (nickel-cobalt-aluminium) is a high energy density lithium chemistry, used notably in some electric vehicles. Powerful but pricier and demanding in thermal management, it favours range. It is close to NMC in its uses.

NMC (nickel-manganese-cobalt) is one of the most common lithium chemistries, offering a good balance of energy, power and cost. It is found in power tools, e-bikes and many power banks. It is slightly less durable and safe than LiFePO4.

The alkaline battery is the most common disposable cell (AA, AAA, 9V formats). Cheap and available everywhere, it suits low-drain devices. It is not rechargeable: for heavy use, NiMH cells are more economical and greener over time.

The button cell is a small round, flat cell powering watches, calculators, remotes and motherboards. Its lithium (CR2032 and so on) or silver-oxide variants differ in voltage and life. Beware: they pose a serious swallowing hazard for young children.

The zinc-air battery produces energy by reacting zinc with oxygen from the air. Very compact and long-lasting, it mainly powers hearing aids. It is activated by removing a tab that lets air in, then discharges gradually even without use.

A power bank is a portable battery that recharges smartphones, tablets and small devices over USB. Its capacity is stated in milliamp-hours, its true useful measure being watt-hours. Recent models feature USB-C Power Delivery for fast, bidirectional charging.

An e-marked cable contains a chip that declares its capabilities (current, voltage, data). It is essential to carry the high power of USB-C, beyond 60 W (100 W to 240 W). A non e-marked cable limits charging or risks overheating under high power.

Pass-through charging lets a power bank recharge a device while charging itself. Handy for a single charging station, it does stress the cells more (charging and discharging at once) and can generate heat. Not every model supports it.

Fast charging refers to the protocols that raise power to cut charging time, negotiating voltage and current between charger and device. Power Delivery and Quick Charge are the main ones. Their effect requires a charger, cable and device compatible with the same standard.

Wireless charging transfers energy by induction between a base and the device placed on it, with no connector. Convenient but slightly less efficient than a cable (conversion losses, heat), it mainly relies on the Qi standard and its Qi2 version. Power stays moderate compared with wired USB-C.

GaN (gallium nitride) is a semiconductor that replaces silicon in chargers. It runs cooler and switches faster, allowing much smaller and more powerful chargers for a given size. A 65 W GaN charger fits in the palm of your hand.

A power bank's stated mAh refer to the internal cells, at 3.7 volts. At the USB output (5 volts), after conversion and losses, the energy actually available is lower: a 10000 mAh bank often delivers the equivalent of 6000 to 7000 mAh at 5 volts. Thinking in watt-hours avoids this confusion.

MagSafe is Apple's magnetic technology that aligns and holds a wireless charger to the back of the iPhone, for more efficient Qi charging and snap-on accessories. MagSafe power banks stick to the back of the phone this way. The Qi2 standard draws heavily on it.

USB OTG (On-The-Go) lets a smartphone or tablet act as a USB host, to plug in a flash drive, a keyboard or read a card directly. It is also what allows a phone to charge another device. Almost all recent USB-C devices support it.

Conversion loss is the energy dissipated as heat each time voltage is changed: from the cells to USB, or from the battery to 230 volts through an inverter. It explains why you never recover 100 per cent of the quoted capacity, usually 80 to 90 per cent.

USB Power Delivery (PD) is the fast-charging standard of USB-C. It automatically negotiates voltage and current, up to 100 W, or 240 W with the PD 3.1 revision. It powers a phone as well as a laptop, and handles bidirectional charging.

PPS (Programmable Power Supply) is an extension of USB Power Delivery that fine-tunes voltage in small steps, in real time. This optimises fast charging and limits phone heating. You need a PPS-compatible charger and device to benefit from it.

Qi is the universal wireless inductive charging standard, adopted by nearly all compatible smartphones. Usual power ranges from 5 to 15 W. You simply place the device on a Qi base, with no cable or connector, at a small energy premium over wired.

Qi2 is the evolution of the Qi standard, with a magnetic alignment inspired by MagSafe. Better positioning improves the efficiency and power of wireless charging while making accessory attachment more reliable. It aims to unify the wireless experience across all smartphones.

Quick Charge is Qualcomm's fast-charging protocol, common on Android devices using its chips. It raises voltage to speed up charging. Its recent versions move closer to USB Power Delivery and become compatible with it, simplifying charger choice.

USB-A is the historic rectangular connector, still present on many chargers and computers. It handles only moderate power and only plugs in one way round. It is being replaced by USB-C, which is more powerful, reversible and versatile.

USB-C is the reversible connector that has become universal for charging and data. Compact, it handles high power through Power Delivery, video and high data rates. Since 2024 it has become the single charging port in the European Union for most devices.

USB-C PD 3.1 is the Power Delivery revision that raises maximum power from 100 to 240 W, introducing voltages up to 48 volts. It lets USB-C power hungry devices such as powerful laptops or some monitors, with a suitable e-marked cable.

A bidirectional USB-C port can both receive and supply power. It is what lets a power bank recharge itself and charge a device through the same connector, or a phone rescue another. This flexibility is made possible by USB Power Delivery.

Trickle charge is a low current kept flowing to offset the self-discharge of an already full battery, without overcharging it. It keeps a car, motorcycle or boat battery ready to use during winter storage. Smart chargers handle it automatically.

Slow charging uses a moderate current to fill a battery over several hours. Gentler, it heats the cells less and spares their life compared with fast charging. It is perfect for an overnight recharge, with no rush.

A cell charger recharges NiMH or lithium cells in common formats (AA, AAA, 18650 and so on). The best models handle each slot independently, show the state of charge and test capacity. A good charger clearly extends the life of rechargeable cells.

A smart charger automatically adapts current and voltage to the battery's state, then cuts off or switches to float once full. It protects against overcharge and detects faulty cells. It is the norm for safely charging modern lithium and lead batteries.

A USB-C charger delivers power through the USB-C connector, most often with Power Delivery for fast charging. GaN models combine high power and compactness, and power a phone as well as a laptop. A single multiport charger can thus replace several bricks.

The charging current is the current, in amperes, sent to a battery while recharging. The higher it is, the faster the charge, but the more the cell heats and ages. It must stay within the maker's recommended limits, often expressed as a C-rate.

Desulfation is a mode on some chargers that tries to dissolve the sulfate crystals built up on the plates of a lead-acid battery discharged for too long. It can restore some lost capacity. Its effectiveness depends on the battery's real condition.

A battery maintainer is a charger meant to stay connected permanently to a rarely used battery (classic car, motorcycle, boat). It alternates monitoring and small top-ups to offset self-discharge, without ever overcharging. Ideal for long storage.

Simultaneous charging is a charger's or station's ability to power several devices at once. The total power is then shared between the ports, so each device may charge more slowly when all are in use. Something to check on multiport chargers.

The charging voltage is the voltage applied to a battery to fill it, specific to each chemistry (for example about 4.2 volts per lithium-ion cell at end of charge). An unsuitable voltage charges poorly or damages the battery, hence the importance of a charger built for the right technology.

An expansion battery is a module you connect to a power station to increase its capacity, without replacing the main unit. It lets you tailor runtime to your needs and grow over time. Each ecosystem has its dedicated batteries, not interchangeable between brands.

Power-saving mode automatically cuts a station's outputs when they draw almost nothing, to stop the unit from draining on standby. Useful for small devices, it can wrongly cut off a very low draw load, which then has to be disabled.

The inverter turns the battery's direct current into 230 volt alternating current, to power appliances on a wall socket. Its power, in watts, sets what you can plug in. The quality of its signal (pure or modified sine wave) matters for sensitive devices.

A pure sine wave is a clean alternating signal, identical to the mains, essential for sensitive devices (electronics, motors, medical equipment). The modified wave, coarser and cheaper, may suffice for simple appliances but makes some equipment hum or overheat.

A power station, or portable power station, is a large battery with multiple outputs (230 volts through an inverter, USB, 12 volts) and often a solar input. It powers appliances while camping, working remotely or as backup power. Its capacity is measured in watt-hours, its power in watts. See our power stations.

The regulated 12 volt output delivers a stable DC voltage, whatever the battery's charge level. Useful for coolers, pumps and 12 volt accessories, the regulation avoids the swings that upset some devices, unlike a plain unregulated cigarette lighter socket.

A power station's 230 volt outlet reproduces a domestic wall socket, fed by the inverter from the battery. It lets you plug in everyday appliances directly, within the inverter's power limit. It is the key output for replacing a mains socket on the move.

Switchover time is the delay a station in backup (UPS) mode takes to take over during a power cut. Expressed in milliseconds, it must be short enough that sensitive devices (computer, router) do not switch off. Below 20 ms, most hold.

A UPS function lets a station switch instantly to its battery during a mains outage, protecting the connected devices. The deciding parameter is the switchover time. Not every station offers a fast enough transfer for this use.

Surge power boost refers to technologies that let a station briefly power appliances whose demand exceeds its rated power, by slightly lowering the voltage. Each brand has its own (X-Boost at EcoFlow, Power Lifting at Bluetti). It does not work with sensitive electronics.

Self-consumption means using on site the electricity produced by your own solar panels, rather than exporting it to the grid. Balcony solar kits and stations with a solar input are simple forms of it, which cut the bill by covering part of your needs.

The photovoltaic cell is the element that converts light into electricity, usually monocrystalline silicon for portable panels. A panel groups many cells in series. Their quality and technology set the efficiency, that is the share of light turned into current.

The temperature coefficient shows how much a solar panel loses in power when it heats up. Counter-intuitively, heat reduces efficiency: a panel performs better in cold, sunny weather than in a heatwave. A low coefficient means better heat tolerance.

The bypass diode protects a solar panel when part of it is shaded: it routes around the shaded cells to stop them blocking all the current and overheating. Thanks to it, partial shading reduces output without cancelling it entirely.

The MC4 is the standard solar panel connector, weatherproof and locking. It makes reliable links between panels and to the controller or station. Its standardisation eases series or parallel wiring, provided polarity is respected.

MPPT (Maximum Power Point Tracking) is a smart controller that constantly adjusts the panel's operating point to extract the most power. Far more efficient than a PWM controller, especially in low light, it equips most good power stations with a solar input.

PWM (Pulse Width Modulation) is a simpler, cheaper type of solar controller than MPPT. It links the panel directly to the battery by chopping the current, but without optimising yield, hence higher losses. It suits small, budget installations.

A bifacial solar panel captures light on both faces, the rear one gathering the radiation reflected by the ground. Well placed (above a light surface), it produces more than a conventional panel of the same size. An asset for balcony and garden installations.

A foldable solar panel folds into several sections for transport and unfolds in use. Compact and light, it is meant for camping, hiking and topping up a power station. Its unfolded surface stays modest compared with a rigid panel.

A portable solar panel is built to be carried and set up easily, often foldable and fitted with a kickstand. It recharges a power station or a battery off-grid, while camping or in a van. Its peak power, in watts, shows the potential in ideal conditions. See our solar panels.

Peak power (in watt-peak, Wp) is a panel's maximum power under standard test conditions. In reality (low sun, heat, imperfect angle), output is often well below, around 60 to 80 per cent. It is a comparison figure, not a guarantee of yield.

The solar charge controller manages energy between the panel and the battery, adapting voltage and preventing overcharge. There are two main families: PWM, simple and cheap, and MPPT, more efficient. On a power station it is built in.

Photovoltaic efficiency is the share of light energy a panel converts into electricity, often 20 to 23 per cent for good monocrystalline panels. High efficiency means more power for the same surface, a key criterion when space is tight.

STC (Standard Test Conditions) are the lab conditions used to rate solar panels: 1000 W/m² of sunlight, 25 degrees Celsius, a defined spectrum. Quoted powers refer to them. Rarely met in the field, they explain the gap between rated and real output.

The open-circuit voltage (Voc) is a solar panel's voltage when not connected, at its maximum. It must stay within the range accepted by the controller or the station's solar input, or damage may occur. It is essential data for wiring panels in series safely.

The XT60 is a rugged, often yellow connector used for the solar or DC input of many power stations. It handles high currents and plugs in with no polarity error. MC4 to XT60 adapters let you connect standard solar panels to it.

AGM (Absorbent Glass Mat) is a sealed lead-acid battery whose electrolyte is absorbed in a glass-fibre mat. Maintenance-free, vibration and discharge resistant, it equips start-stop cars, motorhomes and boats, with better performance than a conventional lead-acid battery.

The alternator is the generator driven by a vehicle's engine, which recharges the starter battery and powers the equipment while driving. In a conversion, a DC-DC charger draws from the alternator to properly recharge an auxiliary battery.

The auxiliary, or leisure, battery powers the living equipment of a motorhome, van or boat (fridge, lighting, USB), independently of the starter battery. Often LiFePO4 or AGM, it is built for repeated deep discharge, which a starter battery cannot handle.

The starter battery delivers a very high current for a few seconds to crank the engine, then is immediately recharged by the alternator. Optimised for instant power (see CCA) rather than deep discharge, it is usually lead-acid, AGM or EFB. See our car batteries.

A jump starter, or booster, is a portable battery able to deliver a strong current to start a vehicle whose battery is flat, without another car. Compact, it slips into the boot and often doubles as a power bank. Check the quoted peak current, matched to the engine size.

CCA (Cold Cranking Amps) measures the current a starter battery can supply when cold (minus 18 degrees Celsius) for 30 seconds while keeping enough voltage. The higher it is, the more assured cold-weather starting is. It is a key figure for choosing a car battery.

A DC-DC charger recharges an auxiliary battery from the vehicle's alternator, adapting the voltage for a full, safe charge, including lithium. It also protects the starter battery. It is the centrepiece of a well-designed leisure circuit.

Jumper cables connect a flat vehicle's battery to a donor vehicle's battery to crank the engine. Their cross-section (in mm²) and the quality of the clamps set the allowable current. Unlike a booster, they require a second vehicle.

EFB (Enhanced Flooded Battery) is a reinforced flooded lead-acid battery, sitting between conventional lead-acid and AGM. It handles cycling better and suits entry-level start-stop vehicles. More durable than a standard battery, it stays cheaper than an AGM.

The cigarette lighter socket is the historic 12 volt socket in vehicles, used to plug chargers, inflators and accessories. Unregulated, its voltage varies with the battery's state and the engine. Power stations often offer an equivalent output, sometimes regulated for more stability.

A battery tester assesses a battery's condition (voltage, capacity, sometimes CCA and internal resistance) to anticipate a failure. From a simple voltmeter to an electronic tester, it helps decide on a replacement. A voltage drop under load is a classic sign of a tired battery.

A resting car battery reads around 12.6 volts when full, and about 14 volts with the engine running (charging by the alternator). Below 12.4 volts it is partly discharged; under 12 volts, starting becomes uncertain. It is a simple indicator of its condition.

A short circuit is a direct contact between a battery's two poles, causing an intense, uncontrolled current. It generates strong heat and, on a lithium cell, a risk of thermal runaway. Fuses, the BMS and protected terminals exist precisely to prevent it.

The fuse and the circuit breaker cut the circuit on excessive current, protecting battery, cables and devices. The fuse destroys itself and is replaced; the breaker resets. In a solar or motorhome setup, they are essential between the battery and the loads.

Thermal runaway is a chain reaction where a lithium cell overheats, which raises its temperature further, up to smoke, fire or explosion. It can result from a short circuit, an overcharge or an impact. Cell quality, the BMS and protections limit this risk.

The IP rating grades a device's resistance to dust (first digit) and water (second). IP65 resists water jets, IP67 a temporary immersion, IP68 a prolonged immersion. It is a key figure for a solar panel, a battery or a lamp used outdoors.

The SDS (safety data sheet, formerly MSDS) is the document describing a product's hazards, composition and precautions, batteries included. It is often required for professional transport and storage, and accompanies shipments of lithium cells.

Overheat protection cuts off or limits a battery or charger when temperature leaves the safe range. Provided by the BMS and sensors, it prevents thermal runaway. It is why a station may reduce its power or shut down in high heat.

Surge protection shields devices and the battery from voltage spikes (lightning, outages, grid faults). On stations and inverters, it stops a surge from damaging the connected electronics. It complements protection against overcharge and short circuit.

The IATA regulations govern the air transport of dangerous goods, including lithium batteries. They set energy limits, state of charge and packaging depending on whether batteries travel alone, inside a device or with it. Airlines base their baggage rules on them.

Air transport of lithium batteries is regulated by their energy in watt-hours. Below 100 Wh, a battery travels in the cabin with no formality; from 100 to 160 Wh, with airline approval; beyond that, it is generally forbidden. Spare batteries always travel in the cabin, never in the hold.

The UN 38.3 standard is a series of tests (altitude, shock, short circuit, vibration and so on) that every lithium battery must pass to be transported legally. It certifies a minimum safety level. A compliant product is the baseline condition for shipping and sale.

A home battery stores a household's electricity, often paired with solar panels, to use later or as backup during outages. Its capacity is counted in kilowatt-hours. Balcony kits and some large power stations are accessible forms of it.

A replaceable battery can be removed and changed by the user, extending the device's life and easing recycling. European regulation is pushing to generalise this design by 2027, notably for smartphones, after years of devices with glued-in batteries.

Eco-design aims to reduce a product's environmental impact across its whole life cycle: materials, repairability, lifespan, recycling. For batteries, it means durable, replaceable and traceable cells. It is a major thrust of the new European regulations.

LCA (Life Cycle Assessment) evaluates a product's environmental impact from raw material extraction to end of life. For a battery, it sheds light on the real carbon footprint, beyond use alone, and guides eco-design and comparisons between technologies.

The battery passport is a digital identity card made mandatory by the European Union (from 2027 for certain batteries). It documents composition, origin, carbon footprint and battery health, to improve transparency, repair, reuse and recycling.

Recycling recovers the metals from used cells and batteries (lead, lithium, cobalt, nickel) to feed them back into manufacturing. Cells and batteries must never go in the bin: free collection points exist in shops. Lead is already recycled at a very high rate.

Reuse means using a battery or device again as is, or after repair, rather than discarding it. It extends life and avoids waste. For batteries, it comes before recycling in the hierarchy of good environmental practice.

Second life gives a new, less demanding use to batteries whose capacity no longer suits their original application (for example electric-car batteries repurposed into stationary storage). It extends their usefulness before recycling and improves their footprint.

Energy storage means holding electricity to release it later, to smooth production and consumption. Home batteries, portable stations and vehicle batteries are all links in it. It is central to making the most of solar and securing supply.

V2G (Vehicle-to-Grid) lets an electric vehicle send electricity back to the grid, turning its battery into a mobile reserve to balance supply and demand. It requires a compatible charge point and vehicle. It is a building block of smart energy management.

V2H (Vehicle-to-Home) uses an electric vehicle's battery to power a home, for self-consumption or as backup during an outage. A car's large capacity can cover several days of essential needs, provided you have the dedicated equipment.

V2L (Vehicle-to-Load) lets you plug appliances directly into an electric vehicle, which then behaves like a large portable socket. Handy while camping or on a worksite, it turns the car into a backup power station through an adapter supplied by the maker.

Theoretical runtime is found by dividing capacity by consumption; real runtime is always lower, because of efficiency, conversion losses, cold and ageing. Allowing a 20 to 30 per cent margin over the calculation avoids nasty surprises.

CE marking indicates that a product sold in the European Union meets the applicable safety, health and environmental requirements. Affixed by the maker, it is mandatory for chargers and batteries. Its absence on an electrical product should raise a flag about compliance.

Backward compatibility lets a newer device work with older hardware, at its performance: a recent USB-C PD charger will power an old phone, but at the speed that phone accepts. Fast charging only happens if charger, cable and device share the same standard.

The manufacturer warranty is the maker's commitment to repair or replace a faulty product for a set period. For a battery, it often also covers a minimum residual capacity after a certain number of cycles. It adds to the statutory warranty of conformity, without replacing it.