Before You Buy an Inverter, Battery or Power Station: Checklist (Printable)
A printable checklist of the specs and questions that matter before buying a home inverter, a battery or a power station, and the sales claims to ignore.
Backup equipment is sold on big numbers that are easy to compare and often mean less than they seem. This checklist covers what actually decides whether a system works for you. Print it and take it to the shop, or keep it open beside the product page.
1. Know your needs first
- List the appliances that must run during an outage, with their watts
- Mark which have motors: fridge, freezer, pump, fans, AC
- Note your longest outage, and the shortest gap between outages
- Work out continuous watts, surge and watt-hours with the inverter size calculator
- Decide fixed system or portable, using power station vs home UPS
2. The inverter (or the inverter inside a power station)
- Continuous rating in watts covers your running load with 20–25% spare
- Surge rating covers your biggest motor starting on top of that load
- Pure sine wave output
- Switchover time, if computers are on backup (ideally under 20 ms)
- Input voltage range, and whether it has a wide "appliance" and a narrow "UPS" mode
- Charging current is adjustable and suits your battery size
- Charging profiles for your battery type: flooded, AGM/gel, lithium
- Standby (idle) consumption, which matters if it runs all day
- Cooling fan and overload, short-circuit and over-temperature protection
- Solar input, if you may add panels later: MPPT, voltage window, maximum watts
- Local service and spare parts, not just a warranty card
3. The battery
- Chemistry: tubular lead-acid, AGM/gel or LiFePO4
- Capacity in Ah at a stated rate (C10 or C20), and the voltage
- Usable capacity: about 50% for lead-acid, 80–90% for LiFePO4
- Cycle life at a stated depth of discharge, not just a number
- For lithium: the BMS continuous and peak current, and low-temperature charge protection
- For lithium: communication with your inverter, or at least the correct charge voltages
- Warranty conditions: pro-rata or full replacement, and what counts as failure
- Manufacture date; batteries age on the shelf too
- Weight and space: floor loading, ventilation for lead-acid
4. A power station specifically
- Capacity (Wh) and chemistry (LiFePO4 preferred for frequent use)
- Continuous and surge AC output
- AC charging watts and time to full
- Solar input voltage range, current limit and maximum watts
- Pass-through / UPS mode and its switchover time
- AC eco mode can be turned off, so low loads like a fridge are not cut
- Expansion batteries available, if you may need more later
- Safety certification for your country
5. Installation
- Battery cable sized for the inverter's full current, with the cable size calculator
- DC fuse or breaker on the positive lead, near the battery
- Ventilated location, out of direct sun, away from gas appliances
- Heavy loads (heaters, irons, kettles, AC) kept off the backup circuit
- Earthing done properly by a qualified electrician
- Charge settings set for your battery before first use
Claims to ignore
- "Runs your whole house": check the watts, not the words
- VA quoted without watts
- Backup hours with no stated load
- Cycle life with no depth of discharge
- "Maintenance-free" on a flooded battery that needs water
For the reasons behind each item, see common UPS installation mistakes and lithium vs lead-acid.
Work it out for your own setup
Common questions
What is the most important spec when buying an inverter?
Its continuous rating in watts, checked against your real load with headroom, followed closely by the surge rating if you will run anything with a motor. VA figures are larger and easily misread; a 1000 VA inverter is typically good for about 800 W.
How do I compare battery warranties?
Read the conditions, not the headline years. A long warranty that is pro-rata after the first year, or that depends on cycle counts, charge settings or installation by an approved dealer, is worth less than it looks. Ask what capacity counts as failed and how a claim is tested.
Is a pure sine wave inverter worth the extra cost?
For most homes, yes. Fans run quieter and at full speed, fridges and motors run cooler, and modern electronics with active-PFC power supplies work reliably. Modified sine wave units are cheaper but cause buzzing, heat and occasional failures in sensitive devices.
