Pretty much every car owner will face the dreaded dead car battery at some point. It’s an almost inevitable part of vehicle ownership, as certain as needing to refuel or change your oil. But what if your battery is beyond just a simple jump start? What if it’s so dead that even days on a charger seem to have no effect? You might think it’s time for a costly replacement, but there’s a cheap car tool available that could bring your battery back from the brink. It might sound too good to be true, like some kind of automotive myth, but I decided to put one of these affordable devices to the test, and the results were genuinely surprising.
Last month, I shared the story of how the compact 12V battery from my wife’s old Toyota Prius, which was residing in my 2008 Smart Fortwo, finally gave up the ghost. This little battery had a long and useful life. Originally in my wife’s Prius, enduring significant mileage each year, it was later repurposed as a robust tool battery. This resilient battery has been incredibly versatile, from jump-starting large trucks to providing power for my project cars when moving them around.
Alt text: Video thumbnail showing a close up of a car battery terminal with jump leads attached, highlighting the topic of battery revival using cheap car tools.
Recently, I had been experimenting with using this Prius battery in my Smart car, aiming to overcome the challenge of its unusually small battery compartment. The experiment was largely successful, until a recent cold snap seemed to finally kill the battery. Initially, I was ready to concede defeat and replace it. However, encouragement from Stephen Walter Gossin and suggestions from readers inspired me to attempt a revival. Not only did I succeed in bringing this battery back to life, but I also managed to resuscitate another battery that had been dead for over a year, proving the effectiveness of this cheap car tool.
Alt text: Image showing a Yonhan cheap car battery charger connected to a car battery, illustrating the battery desulfation process discussed in the article about cheap car tools.
Understanding Battery Death and the Role of Cheap Car Tools
In my past writing for the German Lighting Site, I had a segment called Cool Tool, spotlighting interesting and perhaps lesser-known automotive tools. At that time, my access and resources for hands-on testing were limited, so the features were mainly based on others’ reviews.
Now, my passion for acquiring older vehicles and, admittedly, sometimes neglecting their upkeep, has led me to actually use many of the tools I once only wrote about. I’ve utilized a professional-grade diagnostic scanner to diagnose problems across various cars, employed a borescope camera to aid in reviving classic vehicles, experimented with different electrical connectors, and now, I finally get to experience firsthand how a battery desulfator works. This cheap car tool has truly opened my eyes to affordable automotive solutions.
Alt text: Close up of a car battery with red and black terminals, emphasizing the importance of battery maintenance and the use of cheap car tools for battery repair.
But first, why would you even need a desulfator, one of these Cheap Car Tools? Batteries produce electricity through a chemical process. A typical lead-acid battery contains lead alloy plates and sulfuric acid, acting as an electrolyte. These lead plates function as the anode and cathode. RS Components Ltd., a battery expert, explains this process:
The lead plates act as an anode and cathode, while the sulphuric acid is an electrolyte that contains hydrogen and sulphate ions. Negatively-charged sulphate and positively-charged hydrogen are attracted to the lead cathode and anode respectively. When the appliance or device attached to the battery is turned on, a reaction occurs on the cathode as sulphate ions give up their negative ions and lead sulphate is created. As levels of lead sulphate increase, the electrolyte becomes weaker and resistance on the plates increases. This triggers the flow of negative electrons into the attached device or appliance.
As these electrons flow back into the battery’s cathode, a chemical reaction occurs between hydrogen in the battery and the lead dioxide in this plate. This produces water, meaning hydrogen ions are continuously supplied alongside the sulphate acid inside the battery, enabling the process to restart repeatedly.
In each type of lead acid battery, this reaction will work slightly differently to make it more appropriate to the particular use case its best suited for.
As this explanation suggests, lead-acid batteries are not fans of deep discharge. This is essentially opposite to lithium batteries, which prefer not to be fully charged. Understanding this is crucial for battery maintenance and when considering cheap car tools for battery care.
Alt text: A collection of various car batteries, highlighting different sizes and types, relevant to discussions about battery lifespan and cheap car tools for maintenance.
This chemical reaction is why, as the textbook Batteries In A Portable World points out, batteries in golf carts and similar high-discharge applications often have shorter lifespans than other lead-acid batteries. These types of vehicles typically use deep-cycle batteries, which are built with thicker plates, offer higher capacity, and are designed for frequent charge cycles. However, they are still subjected to significant stress.
Sulfation is a major issue for batteries, as explained in the textbook:
What is sulfation? During use, small sulfate crystals form, but these are normal and are not harmful. During prolonged charge deprivation, however, the amorphous lead sulfate converts to a stable crystalline and deposits on the negative plates. This leads to the development of large crystals that reduce the battery’s active material, which is responsible for the performance.
There are two types of sulfation: reversible (or soft sulfation), and permanent (or hard sulfation). If a battery is serviced early, reversible sulfation can often be corrected by applying an overcharge to an already fully charged battery in the form of a regulated current of about 200mA. The battery terminal voltage is allowed to rise to between 2.50 and 2.66V/cell (15 and 16V on a 12V mono block) for about 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) during the corrective service further helps in dissolving the crystals.
Permanent sulfation sets in when the battery has been in a low state-of-charge for weeks or months. At this stage, no form of restoration seems possible; however, the recovery yield is not fully understood. To everyone’s amazement, new lead acid batteries can often be fully restored after dwelling in a low-voltage condition for many weeks. Other factors may play a role.
Battery Revival with a Cheap Desulfator: Hands-on Test
Alt text: Image of a hand holding a cheap car battery charger, emphasizing the accessibility and affordability of car tools for battery maintenance and repair.
If your car battery dies, you might jump-start your vehicle or take the battery to an auto parts store for a charge. If you’re fortunate, the battery will recover. But, like my experience with the Prius battery, sometimes a regular charge only provides a minimal voltage increase. In the past, I’ve even damaged batteries by attempting to force a charge, causing them to overheat and boil.
I had tried charging the Prius battery for hours, but nothing worked. My charger would either complete the cycle without any real progress, or it would simply fail to initiate a charge. Ready to give up and buy a replacement, Stephen Walter Gossin’s challenge came at just the right moment.
Alt text: Author holding up a cheap car battery desulfator tool, showcasing the device being tested for battery revival as a cost-effective car tool solution.
There are numerous devices available designed to deliver the overcharge described earlier. Essentially, these chargers, known as desulfators, operate by sending pulsing overcharges to the battery needing restoration. These repeated pulses, applied over at least a day, are intended to break down and dissolve the crystalline buildup, restoring the battery’s function and capacity. And surprisingly, you can find cheap car tools that incorporate this technology.
You can purchase a standalone desulfator, or find battery chargers that include a battery repair function. Being budget-conscious, I searched for the most affordable charger with a battery repair feature. I opted for a 10-Amp charger from Yonhan with a repair mode, priced at just $26.99. My decision was influenced by positive Amazon reviews indicating successful battery restoration with this cheap car tool.
First, I decided to use this cheap car tool to attempt to revive the Prius battery. After sitting on another charger for about a day, it held a voltage of only 2.89 volts. Upon connecting it to the Yonhan charger, it quickly indicated a “full” charge within just 10 minutes. I then selected the repair option on the charger.
Alt text: Display screen of a cheap car battery charger showing “PUL” indicating pulse repair mode, illustrating the function of a desulfator as an affordable car tool.
Activating the repair function on this particular unit displayed “PUL” on the screen, signaling that it was initiating pulsing charges to the battery. Observing the pulsing system in action, I saw the voltage briefly peak at 16 volts before dropping back to around 12 volts, repeating this cycle continuously throughout the day. This cheap car tool was indeed working its magic.
Initially, the charger estimated the battery charge at 80 percent, but after about four hours in repair mode, this dropped to 20 percent. I allowed the charger to work on the battery for the remainder of the day. Gradually, the indicated capacity began to increase. Yonhan’s instructions advised regular checks to prevent overheating. The battery did get warm, but never excessively hot.
After a full day on the desulfator setting, the Prius battery reached a standing charge of 12.8 volts—a fantastic improvement! We’ll revisit the Prius battery shortly. Next, I wanted to test this cheap car tool on an even more challenging case: a completely dead Everstart battery. As shown below, the charger initially didn’t even recognize this extremely discharged battery.
Alt text: Image showing a car battery charger failing to detect a deeply discharged car battery, setting the scene for testing cheap car tools for extreme battery revival.
As Batteries In A Portable World explains, the longer a battery remains dead, the lower the chances of successful revival. I decided to test this limit as well, using this cheap car tool.
I used to maintain a collection of spare batteries at home, kept topped up with tenders. However, some were left in parked cars outside, leading to their depletion and my standard Deltran battery chargers being unable to revive them.
One of these casualties was the Everstart battery pictured, dating back to March 2021. This battery died around late 2023 after being left in my project Smart car for too long, meaning it had been dead for at least a year. In fact, it was so lifeless that it had been repurposed as a structural support for my bed frame after a piece broke.
Alt text: Car battery placed in a tight battery compartment of a Smart car, illustrating space constraints and the need for reliable battery solutions and potentially cheap car tools for maintenance.
This OEM-sized battery was actually the reason I started looking for a smaller replacement that would fit better. As you can see, the fit is incredibly tight.
But I wondered: Could this seemingly hopeless battery be revived using this cheap car tool? After finally repairing my bed frame, I put the Everstart battery on the Yonhan charger. Initially, the Everstart was so deeply discharged it registered 0.0 volts on my multimeter—completely undetectable by the charger. To trick the Yonhan charger, I temporarily connected a jump pack in series with the battery. Again, the Yonhan charger quickly indicated a full charge within ten minutes, despite the battery being utterly dead.
Just as with the Prius battery, I selected the repair function and let the Yonhan charger work. It took about two days for this battery to reach the same charge level as the Prius battery had achieved in one day. Over the following week, I alternated charging both batteries on the Yonhan, and gradually, both showed improved charge levels and capacities, according to the charger.
Before proceeding, it’s important to note that batteries can release toxic gases, especially during desulfation. Manufacturers of these devices typically include warnings about this in their manuals. Therefore, it’s crucial to avoid using a desulfator indoors, particularly near pets and children. I placed mine on the deck outside when not actively monitoring the batteries.
Alt text: Car battery charger and battery placed outdoors on a wooden deck, emphasizing safety precautions when using cheap car tools like desulfators, particularly regarding ventilation.
Finally, after a week of desulfation, I disconnected both batteries and allowed them to rest for a weekend. By Monday morning, the Prius battery read about 12.7 volts, while the Everstart showed approximately 12.6 volts. I was truly astonished, especially with the Everstart. None of my other chargers had made any discernible difference with it. I was beginning to understand why some car enthusiasts jokingly call them “Neverstart” batteries.
Of course, voltage is not the only measure of battery health. The real test is performance. I first installed the Everstart in my Smart car, and even on a cold Midwest morning, it cranked the engine to life as if it were a brand-new battery.
As for the Prius battery, I connected it to the Smart car using jumper cables—the same method I use for short-distance car movements—and it also started the car without any hesitation.
The Limitations of Cheap Car Tools for Battery Revival
So, does this mean these batteries are fully restored to their original condition? Not at all.
Alt text: Close up of car battery terminals showing signs of wear and age, emphasizing that while cheap car tools can revive batteries, they cannot fully restore them to new condition.
As Batteries In A Portable World clarifies, batteries suffer permanent damage from sulfation, especially if left dead for extended periods like my Everstart. The extent of this damage varies depending on the battery and circumstances. While a desulfator is an impressive tool, even a cheap car tool like the Yonhan, it doesn’t magically create a brand-new battery. Both test batteries are still four years old and have endured more abuse than they were designed for.
However, a desulfator can, at the very least, revive your battery enough so it’s no longer just a heavy brick of lead and acid serving as furniture support. I’m realistic; these batteries won’t perform as well as they once did. But, if I can extend the life of the Everstart using a solar trickle charger, that’s a worthwhile outcome for me. And all thanks to a cheap car tool.
Alt text: Solar trickle charger connected to a car battery, illustrating a method for maintaining revived batteries and extending their lifespan after using cheap car tools for desulfation.
The automotive experts at MotorTrend tested a battery on a desulfator for two weeks and managed to restore it to 13.1 volts. Their battery continued to function for months afterward. Mine are currently working well, but I plan to put them back on the desulfator to see if further restoration is possible.
My recommendation? If you’re interested in battery restoration, consider investing in a higher-quality charger than the very basic one I used (perhaps something like this). While the Yonhan charger did the job, its build quality is extremely basic—comparable to a toy from a fast-food meal. Its low quality makes me prefer to use it outdoors, just in case something malfunctions. Perhaps I’m being overly cautious, but its construction is noticeably flimsy.
However, if you require absolute battery reliability, buying a new battery is still the most dependable solution. A restored battery remains a damaged battery and might still fail when you least expect it. Yet, this inexpensive $27 charger has proven the effectiveness of battery desulfation. So, if you’re like me and enjoy tinkering, next time your battery dies, instead of immediately discarding it, consider trying to bring it back to life using one of these cheap car tools!
(Images: Author, this post does contain an Amazon affiliate link, and if you click it and buy something we might get a commission – MH)
