Rick's Free Auto Repair Advice

How to buy a car battery jump starter

What to look for when buying a jump starter pack

First, understand the jump starter ratings

Many jump starter pack manufacturers use industry

jump starter pack

Jump-N-Carry JNC770R 1,700 Peak Amps; 425 Cranking Amps

recognized rating terms while others jump starter manufacturers use marketing terms. If you really want to compare apples to apples, you must use compare ratings based on industry standard terms. Here’s what the terms mean:

Peak amps— Peak amps is a marketing term. There is no industry standard that defines how peak amps are measured. So you CANNOT compare a peak amp rating between jumper pack manufacturers. You can only compare peak amp ratings among a single jump starter manufacturers’ different products. Peak amps is NOT an indication of whether it will start your engine.

Cranking Amps (CA)— CA is an industry standard that defines a strict testing routine. The CA rating refers to how many amps a battery can discharge continuously for 30-seconds when the battery is at 32°F (0°C). Some jump starter manufacturers list only a CA rating, while others list both a CA and CCA rating. If you compare just the CA rating between different models and manufacturers, the higher rated model will perform better in normal temperatures.

Cold Cranking Amps (CCA)— CCA is an industry standard that

Schumacher PSJ-4424 DSR ProSeries 4400 peak amps, 500 cranking amps and 415 cold cranking amps

defines a strict testing routine. The CCA rating refers to how many amps a battery can discharge continuously for 30-seconds without falling below 7.2-volts when the battery is at 0°F (-17.77°C). The testing routine requires a new battery that’s chilled to 0°F. The higher the CCA rating, the more powerful the battery. Since a cold engine requires more power to crank and reach minimum RPMS to start, CCA is far more important than either CA or Peak amps.

How much power do you need in a jump starter?

If you’ve properly maintained your engine and are using the proper oil viscosity, here are some guidelines for how many amps you need to start a cold engine.

Commercial truck — More than 500 CCA

Car or truck with a V-8 engine More than 225 CCA

Car or SUV with a V-6 or 4-cylinder engine 150-225 CCA

What convenience and safety features should you look for in a jumper pack?

Jumper pack with Pre-heat

Batteries don’t work well when cold. A jumper pack with pre-heat will use some of the battery’s energy to run a heater. That extra heat more than makes up for the power lost to run the heater.

  • Short circuit protection — This one is pretty simple. The battery pack shut off if you accidentally touch the positive clamp to the negative clamp.
  • Cable length — Manufacturers try to keep cable length as short as possible so they can use a thinner wire gauge. If they make a longer cable, they must use a heavier gauge wire and copper costs money. Yet, you need enough length to attach the cables and set the jumper pack in a safe location while you leave to start the engine. You don’t want the pack to fall down into the engine compartment.
  • Reverse polarity shutdown — The best battery packs prevent current flow if you’ve attached the cables to the wrong posts. This is a critical feature and you’d shouldn’t buy a starter pack without it.
  • Over-voltage — Once the engine starts, its alternator will immediately start charging the battery and your jump starter. Alternator output can be as high as 15.5 volts. That voltage isn’t a problem for jumper packs equipped with lead-acid batteries, but it IS a MAJOR problem for battery packs fitted with a Lithium battery. That high voltage can cause a lithium battery to start on fire or even explode. If you’re buying a Lithium battery jumper pack, over-voltage protection is a MUST.
  • Over-current protection — Over current protection is similar to over-voltage protection. It prevents the jumper battery from overheating based on a high amperage output from the car’s alternator. Here’s why that’s important. These starter packs are designed to recharge at home with a low current (amps) power supply. Recharging at low current prevents damage and ensures long battery life. The power supplies are designed to charge at around 2-5-amps maximum.

But once you start the engine, a car’s alternator can easily output 30-60-amps depending on the engine’s RPM. No jump starter can handle that kind of recharging amperage for long without damaging the battery or starting a fire. That’s why many jumper pack companies state that you must remove the pack IMMEDIATELY after the engine starts. The better packs still say that in their instructions, but they also limit the possible damage by shutting down the pack if alternator amps are too high.

  • Over-temperature protection — When you attach a starter pack unit to a dead battery, you’re instantly draining the starter pack battery. Since lead-acid and lithium batteries produce electricity though a chemical reaction, rapid production of power creates heat—lots of it. High heat can permanently damage a lead acid battery. But high heat in a lithium battery can cause it to explode. The best jumper packs prevent that possibility buy automatically shutting off the pack if internal temperatures exceed a set value.
  • Over-charge protection — This feature allows you to leave your jumper pack connected to the recharging power supply without the worry of battery damage due to over charging. The power supply/charger circuit monitors the battery’s state of charge and shuts off the charger when it’s full.

Lead-acid versus Lithium starter pack — which is best

Lead-acid jumper packs have been the industry standard. They generally pack more CCA than any lithium battery. The downside is that they self discharge at 1-2% per day at room temperatures. They discharge at a slower rate in cold temperatures, but they also output less at those same cold temperatures. Bottom line, you’ll get more power out of a lead-acid jumper pack than any lithium pack. But you’ll have to recharge it more often to keep it full—as often as once a month.

Lithium battery jump starters hold a charge much longer than a lead-acid battery. They’re also smaller and lighter. They do self discharge, but at a much lower rate. In fact, lithium batteries can hold a charge for 60-90 days. However, just like lead-acid batteries, they output less when cold. What’s the downside to Lithium?

  • They’re far more sensitive to heat, so you really shouldn’t store them in the passenger compartment in hot weather.
  • CCA per CCA, they’re more expensive than lead-acid starter packs.
  • They’re not rebuild able. If you own a lead-acid jumper pack and the battery fails, you can order a new battery. That’s not an option for most lithium style starter packs. When they fail, you recycle the old unit and buy a new one.

Here are some examples of popular lithium jumper packs:

NOCO Genius Boost Plus GB40 1000 Amp 12V UltraSafe Lithium Jump Starter NO CA Rating
DBPOWER 600A 18000mAh Portable Car Jump Starter
Antigravity XP-10-HD HEAVY DUTY MICRO-START Massive “actual” 18000 mAh

Lithium jump starter reviews

Be careful when shopping for lithium jump starters! They’re still fairly new and from what I’m seeing, they don’t have a long life. Don’t go by word of mouth. These batteries may work out of the box but fail when you need them most. Read the 1 star reviews before you buy. Here are some examples from Amazon:

“Had high hopes. I had the unit for a few months and kept the battery charged then it hit, dead battery. I tried to jump my Silverado for it’s first use hooked it up I hit the key and nothing! I let the unit charge the battery for a few and still nothing! I checked the XXXXX unit and it’s indicating that the battery on the XXXxxxx is dead!”

“This product does not work in cold weather when a boost is most needed.”

“…..within a year’s ownership I see many customers with the same problem of the battery inside heating up bulging to the point where it breaks the case very dangerous the company should take responsibility and replace them for free.”

Plug in versus clamp jump starters

Plug-in jump starters claim they can start your engine simply by plugging them into the power port or cigarette lighter in the cabin. That way you don’t even have to pop the hood. Do they work? Not really. Here’s why:

Power ports and cigarette lighter sockets are fused to a maximum of 8-12 amps. In other words, your plug in jump starter can only transfer a very small amount of power to your dead battery. You CANNOT JUMP start your engine with a plug-in jump starter. You can ONLY use it to recharge your battery. Even then, a small plug-in jumper battery is simply too small to be any help for a dead battery.

In short, plug in jumper packs are toys. Don’t waste your money on them.

What accessories do you want in a jump starter?

Keep in mind that jumper pack manufacturers want to keep the unit as small and as lightweight as possible while still allowing enough room for the battery. If you buy a jumper pack with a compressor and AC inverter, that’s just less room for the battery. In other words, there’s no free lunch here. If you want all the bells, like an air compressor, AC inverter, flashlight and USB ports, you’re either going to pay a fortune, or you’re going to get a toy. It’s really that simple—there is no one-size-fits-all when it comes to a reliable jump starter that actually works.

What does Rick recommend?

Forget about the compressor and AC inverter. But a jumper pack with the highest CCA rating and the longest cables with all the safety features mentioned above. NOTE: If you plan on spending less than $100, you’ll be getting a toy. You’ve been warned.

Which brand jumper pack is best?

Buy a jumper pack from a company that specializes in

jumper pack

This Schumacher PSJ-2212 jumper pack is rated at 275 cold cranking amps

manufacturing jumper packs. Clore, Solar and Shumacher are the top brands in professional jump starters. They’ve been making them for decades. They’re large enough to have the batteries made to their own specifications, rather than simply buying motorcycle batteries off the shelve and shoving them into a case.

jumper pack

Jumper pack

When it comes to lithium jump starter batteries, be VERY careful. Many of the off-shore import brands are nothing more than cell phone power banks. They have poor safety features, short life spans, and often don’t perform to their specifications.

Lithium jumper pack

CHARGEIT! PP15 lithium jump starter pack

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat



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