Dead batteries are par for the course in automotive sales, service, and repairs, whether in an independent service shop, a collision repair center, or on the showroom floor. For some, it’s an old battery that’s due for replacement such as for a vehicle in used inventory, but in many cases, it’s that the battery has been allowed to discharge for an extended period between starts or in storage.
Key Takeaways
- Jump starters (portable power packs) let you revive a dead battery without another vehicle — ideal for roadside situations.
- Booster cables require a second vehicle with a good battery; they’re lower cost but dependent on having help nearby.
- Modern lithium-ion jump starters are compact, powerful, and can jump most passenger vehicles dozens of times per charge.
- Neither option replaces a failed battery — both only provide enough energy to start the vehicle so it can be driven to a shop.
- After any jump start, the battery should be tested: a weak battery that needed jumping is likely near the end of its service life.
- A Midtronics battery tester confirms within seconds whether a jumped battery is serviceable or needs immediate replacement.
You might need to move the car for clearing snow on the lot, or you may have a prospective purchaser who wants a test drive. There’s an option to track down a jump starter or battery booster pack that’s around the store somewhere or use a set of booster cables. Is there a difference between the two in how it affects battery health? Learn the best option for jump-starting a car to keep the battery healthy.
The Effects on a Battery from Boosting
It’s a common procedure, especially in cold weather when engines need more power to overcome friction and resistance inside, and boosting a battery is typically seen as safe. An external power source, whether a vehicle attached with booster cables or a jump starter pack, is connected to the dead battery. Current flows through large-gauge cables essentially adding an auxiliary capacity to the depleted device. It can generate heat, and it accelerates kinetic energy inside both the dead battery and the donor.
The potential difference between the good battery and the dead one causes a flow of electrons to the dead battery. A sudden voltage spike can occur, and as the potential difference slowly reduces, the energy flow begins to slow.
Seldom do you hear about damage that occurs from boosting a battery, but the potential is present. Primarily, the danger is from the buildup of hydrogen gas from the dead battery that can ignite and explode if a spark is present. Aside from that prospect, heat generated by the fast transfer of electrons can increase the battery’s temperature rapidly, evaporating the electrolyte.
Done correctly and infrequently, boosting a battery can be completed safely, but there’s always a small possibility of ill effects.
Are Booster Cables Safe to Use?
For decades, booster cables, sometimes known as jumper cables, have been used by car owners and repair shops to get dead cars started. And when they’re used properly, it’s generally as safe as any other method. If they’re used once or twice to jump-start a battery until the root cause can be determined and repaired, it’s unlikely that it will cause any damage.
However, the potential for an issue is present with booster cables. It is incredibly simple for even the most experienced technician to mistakenly reverse the polarity on the battery, and should that happen:
- One of many computer modules in a modern car could short out.
- Wiring or fuses could burn.
- A spark could ignite hydrogen gases around the battery.
- And in very rare cases, the battery could explode.
Even if polarity isn’t reversed, connecting the negative clamp to the negative terminal on the dead battery could also cause a spark, sending hydrogen gases alight.
While it’s a common process, due care should always be taken when using booster cables.
Why Jump Starters or Booster Packs Are Popular
Jump starter packs, sometimes called portable battery packs, booster packs, or power packs, are an incredibly popular option for businesses in the automotive industry. First, it mitigates instances where a particular vehicle is frequently used as a donor vehicle, constantly straining both the alternator and the battery. Secondly, it’s extremely portable and can be used in all instances such as when a dead vehicle is parked with the battery impossibly difficult to reach with booster cables.
And while they’re popular, automotive businesses can relate to a couple of deterrents. Jump starter packs are more expensive than a typical car battery, and they find legs more frequently than anyone would like to admit. Replacing them is cost-prohibitive, and it’s a hassle in many cases to administer when they’re going out and coming in. Plus, where there’s always a vehicle nearby that can be used for a boost, limited numbers of jump starters can mean it’s frustrating to wait for one to come available.
Jump Starter Offers Some Protection
When comparing jump starters vs booster cables, there is a clear leader in terms of safety and battery health. Used properly, they might function the same, but a jump starter has safeties built in that help prevent damage to a battery. An integral battery management system can regulate the current delivered to a battery, ensuring a modest thermal response.
Most importantly, the battery’s health is protected against reversing the polarity. Most battery jump starters detect reverse polarity automatically and prevent a connection with the internal battery. Since the largest risks are related to reverse polarity, this is where jump starters excel over booster cables.
The Best Option? A Slow Charge
However, there’s a better option rather than either booster cables or jump starter packs. When it’s possible to connect a battery charger at a low amperage rate, it protects the battery’s health and not just gets the car running, but fully replenishes the charge.
One of the most challenging issues with jump starts is that, often, the car being boosted doesn’t run long enough to top up the battery’s energy stores. They get moved, parked, and shut off, and another boost will be required in short order. Even if a car gets jump-started, future problems can be avoided if they’re placed in a queue to charge the battery fully.
Not only will it avoid aggravation for staff and customers when batteries are fully charged, but it prevents instances of replacements that could’ve been avoided. A good practice is to train all staff – service, parts, and sales – in the proper use of jump starters, booster cables, and battery chargers, and maintain diagnostic battery chargers that can be used.
Frequently Asked Questions
What is the difference between a jump starter and booster cables?
Booster cables (jumper cables) transfer power from a running vehicle’s battery to a dead one. A jump starter is a self-contained portable battery pack that delivers starting power without needing a second vehicle. Jump starters are more convenient for solo drivers; booster cables are cheaper and never need charging.
Is a jump starter better than booster cables?
For most drivers, a portable jump starter is more practical — you’re not dependent on another driver stopping to help. Modern lithium-ion jump starters are compact enough to fit in a glove compartment and can start most vehicles multiple times. However, booster cables are inexpensive, never run out of charge, and are ideal as a backup in a shop environment.
Can jump starting damage a modern car’s electronics?
Done correctly, jump starting is safe for modern vehicles. The risk comes from connecting cables in the wrong order or polarity. Always connect positive to positive and negative to a chassis ground (not the dead battery’s negative terminal). Some vehicles with sensitive electronics benefit from using a jump starter with a controlled current output rather than a direct vehicle-to-vehicle connection.
How many times can a portable jump starter be used?
It depends on the unit’s battery capacity. Most quality lithium jump starters can deliver 20–40 jump starts on a full charge. They should be recharged every 3–6 months when stored, as lithium batteries lose charge slowly over time. Check the charge indicator before relying on one during an emergency.
Should I replace my battery after a jump start?
Not necessarily — but you should test it. A battery that went completely dead due to accidentally leaving lights on may be fine once recharged. A battery that died during normal use likely has an underlying problem. Bring the vehicle to a shop for a conductance-based battery test to determine whether replacement is warranted.
Can jump starters work on EVs?
Conventional jump starters work on the 12V auxiliary battery in hybrid and electric vehicles — the one that controls system startup. They cannot charge or jump the high-voltage traction battery. If an EV’s 12V auxiliary battery fails, it can prevent the HV system from powering on, so keeping that battery in good health is critical.