Peak Amps

How we research

Peak amps is the maximum current a jump starter advertises it can deliver for a very short burst.

Last updated: 19 October 2026

What it means

A seller’s own blog, WOLFBOX, says peak amps is a very brief maximum burst, not the sustained current an engine needs to turn over, and that there is no industry-wide test standard for it, so makers can measure it under different conditions [1]. That is one seller’s view, but it matches why the figure is hard to compare.

Why it matters when you buy

The blog says two devices with very different peak amp claims can perform similarly in real starts, and advises choosing a pack with a published cranking-amp rating rather than peak amps alone [1]. Check the maker’s engine size rating for your fuel as well.

How you will see it

A UK seller lists the NOCO GB20 at 500 A peak, rated for petrol engines up to 4.0 litres with no diesel limit listed [2], and the NOCO GB50 at 1,500 A peak, rated for petrol up to 7.0 litres and diesel up to 4.5 litres [3]. The peak figure is three times larger, but the petrol limit is only 1.75 times larger, so you cannot read engine suitability from peak amps alone.

Sources

  1. Sizing a jump starter correctly: peak amps, CCA and the numbers sellers don’t explain, WOLFBOX (seller’s own blog). Dated 7 August 2026, wolfbox.com. Checked 19 October 2026.
  2. NOCO GB20 Boost Sport 500A jump starter, Tayna (UK seller listing), tayna.co.uk. Checked 19 October 2026.
  3. NOCO GB50 Boost XL 1500A jump starter, Tayna (UK seller listing), tayna.co.uk. Checked 19 October 2026.