Every charger gets a score from 0 to 100% built from four 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. Chargers are grouped by bank count, 1 and 2 banks and 3 and 4 banks.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per amp of total charge current | 30% |
| Charge current | total charge current across all banks | 15% |
| Features | lithium mode, waterproofing, temperature compensation and a display | 25% |
| Warranty | warranty length | 30% |
Where the numbers come from
Banks, current, charge profiles, water rating and warranty come from the maker’s spec sheet, manual or product page. Prices are checked at Amazon, the maker’s own store and marine retailers, and the lowest is used.
The factors
Value is the current price divided by the total charge current across all banks, on a log scale, so halving the price per amp always counts the same. $40 per amp scores zero and $8 full marks.
Charge current is the total across all banks. For 1 and 2 bank chargers 6 A scores zero and 30 A full marks; for 3 and 4 bank chargers 15 A scores zero and 60 A full marks.
Features counts four things equally: a lithium (LiFePO4) charge profile, a water rating of IP67 or better, temperature compensation, and a display or app that shows each bank’s charge level.
Warranty is the maker’s warranty: 1 year scores zero and 5 years full marks.
What isn’t scored
An AGM profile, full potting, ignition protection and weight are listed but not scored.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. The exception is warranty: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero, the same as the shortest warranty on the scale, and is marked estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.