Retail packaging is heavy on glossy pictures and bold claims. What’s more, it isn’t limited to groceries and department stores. You will find it in the auto store, too. Take the simple portable jump starter. Manufacturers are not afraid to print bold statements like ‘3,000 peak amps’ in the largest possible font in order to catch wandering eyes as customers browse.
Here’s the problem: as any experienced auto mechanic or towing contractor can testify, retail packaging does not start a dead delivery truck on a cold winter morning. What manufacturers often claim as selling points have only minimal impact in real-world scenarios. As for pro mechanics and tow operators, they need to know the metrics that really matter.
Peak Amps Are an Illusion
Anyone looking to buy a portable jump starter needs to understand peak amps and what they represent. An amp is a measurement of the amount of current being produced. So in terms of a jump starter, peak amperage represents the absolute maximum amount of current the unit can deliver in a fraction of a second. It represents the initial, instantaneous spike of energy that flows from the unit as it’s turned on. But it is an illusion as far as turning over a cold engine.
A high peak amp rating is impressive on paper because people appreciate big numbers. But it’s largely a marketing metric. Why? Because engines don’t turn over and start in the one millisecond a jump starter is producing peak amps. Under the right conditions, it takes at least a second or two. When you are talking about a large-displacement diesel engine on a cold winter morning, you could be looking at five seconds or more. Peak amperage doesn’t last that long.
Starting a cold engine with a dead battery typically requires a sustained, heavy flow of electrical current over many seconds. The jump starter has to help the engine overcome dead weight to build compression. A unit that delivers only a massive burst of current for a millisecond before falling flat limits its ability to do its job.
Cold Cranking Amps Are More Important
An auto mechanic invests in a portable jump starter so that he can start cars with dead batteries. So instead of obsessing over peak amps, mechanics should be looking at cold cranking amps (CCA) instead. CCA is the measurement of how much power a unit can continuously deliver for a minimum of 30 seconds at 0 °F without dropping below the critical voltage threshold.
CCA is a better metric than peak amps. But it does have an inherent flaw: industry-standard CCA ratings are based on a highly specific, rigorous laboratory testing environment. Most portable jump starters cannot be accurately measured under lab conditions because their battery packs are too small. But Clore Automotive experts say there is another metric mechanics can look at: cranking amps (CA).
The Best Metric for Pros
The best metric for pros looking for a portable jump starter is CA. It is a measurement of the amount of sustained current a jump starter can deliver for a full 30 seconds at 32°F. CA bridges the gap between the marketing department’s peak amperage and the lab’s CCA. If a portable jump starter offers a high CA rating, the internal battery chemistry is capable of getting the job done.
The only other thing the pro needs to look at is the unit’s construction. Ideally, he wants heavy-gauge cabling and rugged terminal clamps. He wants a tough case that will stand up to the punishment of daily work in the trenches.