A quite complex topic.

  • Voltage
    • Nominal
    • Open-circuit
  • Energy, in units (e.g.) mAh, Ah, kWh
  • Chemistry
  • Self-discharge rate
  • Shelf life
  • Rechargeable or Not
    • Coins/Buttons – never
    • Cylindrical (AA, AAA, …) – some, majority not
    • Larger – yes
  • Rechargeable
    • Charger complexity
    • Cycle times
    • Memory
  • Costs
    • Initial, purchase
    • Operational, during life time
    • Life-time expectancy
    • TCO
  • Temperature
    • Operating
    • Storage

Examples of batteries you may already have, or could contemplate, in order of smaller to larger (to the larger degree):

Button Batteries, Coin Batteries

Those small coins used in some remote controls, smaller flashlights, digital watches, computer motherboards to hold settings and real-time clock (RTC).

Not useful for any form of energy storage/backup power but your electronics may stop failing if run out of these small babies. Know which models you need, keep a stock, and know where those are.

Cylindrical Batteries

D1.25-1.52000-5000 mAh NiCd
2200-12000 mAh NiMH, rechargeable
12000 mAh Zinc-carbon
12000 mAh Alkaline
C1.5up to 3800 mAh Zinc-carbon
up to 6000 mAh NiMH, rechargeable
up to 8000 mAh Alkaline
AA1.2-1.8400-900 mAh Zinc-carbon
1000-1500 mAh Zinc-Chloride
1700-2850 mAh Alkaline
AAA1.2-1.5500 mAh NiZn
540 mAh Zinc-carbon
800-1000 mAh NiMH, rechargeable
1200 mAh Alkaline

Rectangular (smaller, household)

(Not the batteries in cars, boats, golf-carts etc)

9-Volt9400 mAh Zinc-carbon
175-300 mAh NiMH, rechargeable
550 mAh Alkaline
1200 mAh Lithium
12Many different sizes (physical and energy capacity), with common capacities in 5 to 10 Ah.

Cell Phone Power Banks

From a low 1,000s mA up to tens of Ah (10,000 mAh+). Capacity is most often given in mAh.

Connectors for charging using (e.g.) Micro USB, some also have USB C, and USB-A and even in some cases Lightning for connecting to cell phone/tablet.

Lead-Acid Batteries

  • Automobile starting, lightning, and ignition (SLI) – NOT designed for deep-discharge
    • High-current for shorter time, starting heaving engine
  • Traction (propulsion) batteries in golf carts, electrical vehicles
  • Valve-regulated lead-acid (VRLA) in UPSs, scooters, wheelchairs, bicycles, …
  • Wet cell stand-by (stationary), deep discharge, large backup supplies in telecom and data centers, grid energy storage, and off-grid household electric power system
  • AGM, Absorbed Glass Matte
  • GEL cell

Common capacities on automotive including marine/RV batteries are in areas ot 30 Ah to 100 Ah.

Automotive Batteries

Primary duty is starting (cranking) more or less heavy gasoline or diesel engine, secondary duty including lighter loads like some lights and ignition.

Marine Batteries, RV Batteries

More dual-purpose – both cranking and deep-cycle, latter for providing continuous power for more electronics over longer time (navigation aids, radios, refrigerator, trolling motor, …)

UPS Batteries

Keep this in mind: if you have UPSs for computers, multimedia components, et c, these can be great sources for electrical backup power. In case of electrical outage, safely shutdown computers/etc, disconnect components and use the UPS(s) for emergency-level use (charging cellular phones, source of emergency radio, et c).

Commonly 12V nominal voltage but be aware of chemistry as some batteries will require charger specifically made for certain chemistries!

Capacities varies between some 10 Ah up to 40-50 Ah, and even 100 Ah.

Home energy storage

A.k.a Battery Energy Storage System (“BESS”)

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Electrical Vehicles Batteries

Common topics, independent of sizes of batteries:


Discharge – including table with common self-discharge rates for different chemistries.

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