Buy the right battery once
Battery shopping is mostly guesswork, and the guesses are expensive. This site works in the units that matter — amp-hours, depth of discharge, cold cranking amps — and tells you what each chemistry is actually good at.
Start with the application
Golf cart batteries
Six 8V flooded cells or a 48V lithium pack — what each costs, how the ranges differ, and why heat kills lead-acid in the south.
Lithium & solar storage
LiFePO4 in practice: depth of discharge, cycle life, cold-weather charging limits and what a usable kWh really costs.
Portable power stations
Watt-hours, inverter surge, solar input and recharge time. How to size one for outage length rather than marketing claims.
RV & marine batteries
House bank vs starting battery, why marine dual-purpose compromises, and sizing a bank around real daily loads.
Tools that do the arithmetic
Runtime calculator
Enter load watts, battery amp-hours and voltage, get real runtime after inverter losses and a safe depth of discharge.
BCI group size chart
The physical sizes that decide whether a battery fits the tray: dimensions and terminal layout for common groups.
CCA, Ah and reserve capacity
The three numbers on every label, what each one actually measures, and which one your application cares about.
Where the money actually goes
A replacement golf cart pack runs roughly $600-1,100 in flooded lead-acid, or $1,500-2,600 for a 48V lithium conversion that lasts three to four times longer. A power station sized for a fridge plus a few lights for two days starts around $700 and climbs past $3,000. The right answer depends on cycle count and how long you plan to keep the equipment, which is why we compare on cost per usable kilowatt-hour over life rather than sticker price.
Everything on this site is written to be useful before you buy and after the box arrives. If a number here disagrees with your owner's manual, the manual wins.