A home battery datasheet is the closest thing to a contract you will see before an order. It is where a supplier states what a product stores, delivers, survives — and, if you read the footnotes, the conditions under which those numbers are true. This guide walks through the lines that matter most for residential installers and distributors, and the questions to ask whenever a figure has no test condition attached.
Start with usable capacity, then check the conditions behind it
The headline figure on a home battery is almost always energy capacity in kilowatt-hours (kWh). For a LiFePO4 pack, the two inputs behind that figure are nominal voltage and amp-hour rating: multiply the two and you get nominal energy. The Woolii Storage Wall series is a straightforward example.
| Model | Nominal energy | Nominal voltage | Capacity | Notes |
|---|---|---|---|---|
| SEN-W48050 | 2.56 kWh | 48 V | 50 Ah | IP65 outdoor capable |
| SEN-W51100 | 5.12 kWh | 51.2 V | 100 Ah | Wall-mounted |
| SEN-W51200 | 10.24 kWh | 51.2 V | 200 Ah | Wall-mounted |
| SEN-W51280 | 14.34 kWh | 51.2 V | 280 Ah | Wall-mounted |
The arithmetic is simple. What the datasheet does not always make obvious is that usable energy depends on how fast you discharge and at what temperature. A capacity stated at a gentle C/20 discharge is not the same as the energy you can pull at a 0.5 C continuous load, and most suppliers rate cells at 25 °C. When a number appears with no charge or discharge rate and no temperature, ask for the test condition. That single question is the fastest way to tell a datasheet written for engineers from one written for marketing.
Voltage: nominal vs operating window
The nominal voltage (48 V or 51.2 V in the table above) is the average during discharge, not the full operating range. LiFePO4 packs work across a band of voltages, and the inverter has to track that window correctly. Voltage architecture also drives compatibility: a 51.2 V low-voltage pack belongs to a different class of hybrid inverter than a high-voltage system. For residential retrofits, 48–51.2 V low-voltage architectures remain the most common because they pair cleanly with mainstream hybrid inverters and keep DC cabling within familiar limits. Before you assume a pack will talk to an inverter you already stock, check the same questions installers should ask about any LiFePO4 storage supplier.
Cycle life means nothing without its test conditions
Cycle life is the number suppliers quote most and readers trust least — for good reason. A cycle is one discharge and recharge to a defined depth of discharge (DoD), and the figure only means something when DoD, temperature, and the end-of-life definition are stated. "6000 cycles" tells you little; "6000 cycles to 80% capacity retention at 80% DoD and 25 °C" tells you a lot. Our guide to LiFePO4 cycle life explains what the standard claim does and does not cover. When you compare two suppliers, put the cycle-life figures side by side with their conditions. If the conditions are missing, treat the number as unverified rather than superior.
Power and C-rate: what the battery can actually deliver
Energy tells you how long a load can run; power tells you whether the battery can start it. Datasheets list continuous discharge power and often a peak figure for surges, and the relationship is expressed as a C-rate. A 5.12 kWh pack at 0.5 C delivers about 2.56 kW continuous. Check that the continuous rating covers the household base load plus the appliances you expect to run, and that the peak rating lasts long enough to start inductive loads such as pumps and compressors, which draw several times their running current for a few seconds.
Round-trip efficiency and standby consumption
Round-trip efficiency describes how much of the energy put into a battery comes back out. It matters for payback calculations, and it is one of the most test-dependent numbers on the sheet: charge and discharge rates, temperature, and the DC/AC boundary all change it. Standby consumption — the power the battery and its BMS draw while idle — matters for a different reason. A system sized for backup can sit for days, and idle draw quietly erodes the energy you stored.
Operating temperature: charging and discharging have different limits
Most residential batteries discharge across a wider temperature range than they can charge. Charging a LiFePO4 pack at low temperature is where damage risk concentrates, so a datasheet that separates charge and discharge temperature limits is a sign of an engineering-first supplier. This is also where the datasheet meets the install site: a battery rated for a garage is not automatically rated for an unheated outdoor wall. If the site has no conditioned space, look for an IP-rated outdoor variant and read its temperature range instead of assuming. Our guide to IP65 outdoor batteries covers when that matters.
Certifications: read the compliance section, not the marketing paragraph
Certifications decide whether you can legally and safely install a product in your market. Look for the standard name and a certificate or report reference tied to a specific model — not a general sentence about international standards. A datasheet line that says "engineered to meet" is not the same as "listed to", and an installer who relies on the first can discover the difference at inspection. Our explainer on what a UL 1973 listing actually covers is worth reading before you evaluate any supplier claim.
A short checklist before you quote
- Capacity: is nominal or usable energy stated, and at what discharge rate and temperature?
- Voltage: does the operating window match the inverter and the site DC cabling?
- Cycle life: are DoD, temperature, and the end-of-life definition all present?
- Power: does continuous output cover the base load, and is the peak long enough for motor starts?
- Efficiency: what is the round-trip figure, and under what test conditions?
- Temperature: are charge and discharge limits separate, and do they fit the actual install location?
- Certifications: standard name plus a model-specific certificate reference, not a marketing sentence.
- Supplier behaviour: does the supplier send the full datasheet with test conditions before you quote? That willingness is itself a signal, as our supplier evaluation framework explains.
Where to get the full picture
The table above is drawn from the Woolii Storage Wall series. The detailed datasheets — including cycle-life test conditions, full temperature limits, and the verified inverter compatibility list — are available on request, and we publish specifications with their test conditions rather than a bare headline. If you are planning a quote this week, start with the Storage Wall series and the hybrid inverter range. For an independent walk-through of the full set of spec-sheet terms, Solar Choice's battery specification guide explains them in plain language.