Every 12V lithium 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. Batteries are ranked within their size: small (under 100 Ah), the 100 Ah class (100 to 199 Ah) and large (200 Ah and up).
| Factor | Measures | Weight |
|---|---|---|
| Value | price per rated watt-hour | 35% |
| Tested capacity | independently measured capacity versus rated | 15% |
| Output | continuous BMS current | 15% |
| Warranty | warranty length | 15% |
| Cycle life | rated cycles | 10% |
| Cold weather | self-heating or low-temperature charge protection | 10% |
Where the numbers come from
Rated capacity, BMS current limits, cycle life, cold-weather protection, size, weight and warranty come from the maker’s spec page, datasheet, manual or warranty terms, linked on every product page. Where a maker gives only amp-hours, watt-hours are amp-hours times the nominal 12.8 V.
Tested capacity comes only from independent reviewers who discharged the battery from full to its BMS cutoff and published the result. A maker’s own figure never counts as a test.
Reference points by size
| Size | Price per rated Wh, scoring 0 → 100 | Continuous current, scoring 0 → 100 |
|---|---|---|
| Small (under 100 Ah) | $1.00 → $0.15 | 20 A → 100 A |
| 100 Ah class (100 to 199 Ah) | $0.70 → $0.10 | 50 A → 150 A |
| Large (200 Ah and up) | $0.60 → $0.09 | 100 A → 300 A |
The factors
Value is the lowest checked price divided by the rated capacity in watt-hours. Prices are checked by hand and dated on every page. Small batteries always cost more per watt-hour, so each size has its own scale. A battery with no current price gets the neutral middle score.
Tested capacity is the capacity independent reviewers measured, as a share of the rated capacity, averaged across tests: 90% scores zero and 100% or more full marks. Most LiFePO4 batteries deliver at least their rating when new, so a shortfall is a warning sign about the cells inside. An untested battery gets the neutral middle score and is marked estimated.
Output is the continuous discharge current the BMS allows, which sets the biggest inverter or trolling motor the battery can run on its own. Each size has its own scale; a 100 A BMS supports about a 1,000 W inverter at full load, and 200 A about 2,000 W. The usual 100 A for a 100 Ah battery, and 200 A for a larger one, land in the middle of the scale.
Warranty is the length of the maker’s warranty, from 1 year (zero) to 9 years or more (full marks). The common 5-year term lands in the middle.
Cycle life is the maker’s rated number of charge cycles, from 1,000 (zero) to 7,000 (full marks), with the common 4,000 in the middle. Makers rate cycles at different depths of discharge and end-of-life capacities, and no one checks the claims, so this factor counts for little and is always marked estimated.
Cold weather scores whether the battery can be charged safely below freezing. Charging LiFePO4 cells below 32 °F damages them. A built-in heater that warms the cells before charging scores full marks; a BMS that only blocks charging in the cold scores 60%, since it protects the battery but leaves it unable to charge from solar or an alternator on a cold morning; a battery with neither scores zero. Where the maker doesn’t say, the factor gets the neutral middle score and is marked estimated.
What isn’t scored
Bluetooth monitoring, case size and weight are shown and can be filtered, but aren’t scored. Bluetooth is worth having when the battery has no separate monitor. The self-heating and Bluetooth lists show only those. Peak current, maximum charge current and series or parallel limits are listed where published.
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 size. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.