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What size jump starter do you need?
Updated
Enter your engine size and your winter weather. The picker gives you the maker engine rating to look for and shows which of our picks cover it.
What engine rating should you look for?
We multiply your engine size by 1.25 for mild weather, 1.5 for cold and 2.0 for severe cold. This headroom is our rule of thumb, not a maker figure. Engine ratings are the makers' claims from their Amazon listings. Always follow your vehicle manual.
Why add headroom
- The maker's rating is a best case. It assumes a full pack and good clamp contact. Yours may have sat in the trunk for months.
- Cold makes everything harder. Cold oil is thick, so the engine is harder to turn. A cold lithium pack also gives less power. Both hit on the same morning.
- Diesels need more. Diesel engines have higher compression. That is why every listing gives a smaller diesel number than gas number. Always use the diesel rating for a diesel.
Worked examples
| Vehicle | Climate | Rating to look for | Our picks that cover it |
|---|---|---|---|
| 2.5L gas sedan | Cold | 3.8L gas | NOCO Boost GB20, NOCO Boost GB40, NOCO Boost GBX75, GOOLOO A3 with air compressor, GOOLOO GP4000 |
| 3.5L gas minivan | Cold | 5.3L gas | NOCO Boost GB40, NOCO Boost GBX75, GOOLOO A3 with air compressor, GOOLOO GP4000 |
| 5.7L gas pickup | Cold | 8.6L gas | GOOLOO A3 with air compressor, GOOLOO GP4000 |
| 3.0L diesel SUV | Cold | 4.5L diesel | NOCO Boost GBX75, GOOLOO A3 with air compressor, GOOLOO GP4000 |
| 6.7L diesel pickup | Mild | 8.4L diesel | GOOLOO GP4000 |
| 6.7L diesel pickup | Cold | 10.1L diesel | none of our picks |
The last row matters. A big diesel in a cold place is past what the small lithium packs on our list claim. Many big diesel trucks also use two batteries. Check your vehicle manual for the jump starting steps, and ask a mechanic if you are not sure.
Ready to compare? See the five picks.