Every jump starter 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. Jump starters are grouped by the largest gas engine the maker rates them for, and each group has its own scale.
| Factor | Measures | Weight |
|---|---|---|
| Value | price for its engine size | 40% |
| Features | manual override, cold rating, USB-C charging, water resistance | 35% |
| Capacity | battery size for phones and repeat jumps | 15% |
| Warranty | warranty length | 10% |
Where the numbers come from
Engine ratings, capacity, features and warranty come from the maker’s product page, manual or warranty page. Peak amps are the maker’s own figure with no agreed test behind them, so we list them but don’t score them. Cranking current measured by independent testers is shown on product pages where it has been published.
The groups
| Group | Rated gas engine |
|---|---|
| Cars and SUVs | up to 7 L |
| Trucks and V8s | over 7 L, up to 9 L |
| Heavy duty | over 9 L, or “all gas engines” |
A few makers, mostly of lead-acid boosters, give no liter figure and rate a pack for, say, “any gas engine up to V8”. Those are grouped by the maker’s wording, which the product page shows.
The factors
Value is the current price, scored on a scale for each group:
| Group | Scores 0 | Full marks |
|---|---|---|
| Cars and SUVs | $150 | $40 |
| Trucks and V8s | $250 | $60 |
| Heavy duty | $450 | $100 |
Features adds up the things that make a jump starter work when you need it:
| Feature | Share of the factor |
|---|---|
| A manual override that can start a battery reading near 0 V | 40% |
| Lowest operating temperature, from 32 °F (none) to −22 °F (full) | 30% |
| Recharges over USB-C, scaled up to 30 W | 20% |
| A water-resistance (IP) rating | 10% |
Most jump starters refuse to fire into a battery that reads almost no voltage, as a safety check; an override lets you start a car whose battery is completely flat. Lithium cells lose power in the cold, so a pack rated to work well below freezing is the one that starts a car on a winter morning. A feature the maker doesn’t state either way gets half credit.
Capacity is the battery’s stated energy in watt-hours, which decides how many jump attempts and phone charges you get between recharges:
| Group | Scores 0 | Full marks |
|---|---|---|
| Cars and SUVs | 20 Wh | 60 Wh |
| Trucks and V8s | 30 Wh | 90 Wh |
| Heavy duty | 40 Wh | 120 Wh |
Packs that only state milliamp-hours get the neutral score, because mAh figures are quoted at different cell voltages and can’t be compared reliably.
Warranty: 1 year scores zero and 3 years full marks.
What isn’t scored
Peak amps, flashlights, air compressors, USB output power, size and weight are listed but not scored. Independent 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 group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.