Every 48 V battery gets a score from 0 to 100% built from six factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Server-rack modules and wall- or floor-mount batteries are ranked separately.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per rated kWh | 35% |
| Output | continuous discharge power for its capacity | 15% |
| Warranty | warranty length | 15% |
| Safety listing | UL 1973 and UL 9540 / 9540A | 15% |
| Cycle life | rated cycles | 10% |
| Features | inverter communication, self-heating and app | 10% |
Where the numbers come from
Capacity, current ratings, cycle life, certifications, features and warranty come from the maker’s datasheet, manual, certificate or warranty page. A UL standard counts only where the maker states the battery is certified, listed or tested to it, not merely “compliant” or “pending”, and cell-level reports don’t count for the whole battery.
The factors
Value is the price divided by the rated capacity: dollars per kWh. $600 per kWh scores zero and $150 per kWh full marks. Rated capacity is the maker’s watt-hour figure, or amp-hours times the nominal voltage.
Output is the continuous discharge power as a share of capacity, so big and small batteries are judged alike. A battery that can deliver 30% of its capacity per hour (0.3C) scores zero, and one that can deliver all of it in an hour (1C) gets full marks. More output means fewer modules to run a big inverter at full power: a 5 kWh module rated 100 A gives about 5 kW.
Warranty: 3 years scores zero and 10 years full marks. Many 10-year warranties also end at a set number of cycles or a set amount of energy delivered; the product page notes those conditions.
Safety listing is half for a UL 1973 listing, the safety standard for the battery itself, and half for UL 9540A fire testing or a UL 9540 system listing, which most US inspectors ask for before a battery goes inside a home or garage.
Cycle life is the maker’s rated number of full cycles: 3,000 scores zero and 8,000 full marks. Makers rate cycles at different depths of discharge and end-of-life capacities, so this is the maker’s claim, not a measured figure; it’s marked as modeled.
Features adds up the things that make a battery easier to live with:
| Feature | Share of the factor |
|---|---|
| Closed-loop communication with named inverter brands (half credit for CAN or RS485 ports with no list) | 40% |
| Self-heating, so it can charge below freezing | 30% |
| A Bluetooth or Wi-Fi app built in | 30% |
A feature the maker doesn’t state either way gets half credit.
What isn’t scored
Peak current, charge current, parallel limits, display, built-in breaker, enclosure rating, size and weight are listed but not scored. Independent capacity tests are listed where they exist, but there are too few to score.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated.
Ties and discontinued models
Products are ranked by score within each case type. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.