Everyone who’s owned a car has likely faced the dreaded dead battery. It’s an automotive inevitability, right up there with needing new tires or realizing you left the lights on again. But what happens when a car battery dies, truly dies? We’re talking about a battery that’s been on a charger for ages and still refuses to hold a decent charge. Before you resign it to the scrap heap, consider this: there’s a way to bring these batteries back to life and give them a second purpose – powering your tools. It might sound too good to be true, but with a little ingenuity and the right tools, you can create a Car Battery Bank For Tools, offering a robust and portable power solution for your garage or workshop.
This isn’t about snake oil or magical fixes. It’s about understanding battery chemistry and leveraging a simple, affordable technology called a desulfator. Recently, I tested one of these devices on a couple of stubbornly dead car batteries, and the results were genuinely surprising.
You might recall my previous experiment with a slim Toyota Prius 12V battery in my 2008 Smart Fortwo. This little battery was a workhorse. Originally from my wife’s Prius, it endured years of heavy use before I repurposed it. It became my go-to power source for everything from jump-starting trucks to briefly powering project cars.
Alt text: A close-up view of a small 12V car battery, previously used in a Toyota Prius, now repurposed for various automotive tasks.
I had been using it in the Smart car, trying to solve a cramped battery compartment issue. The experiment was going well until a cold snap seemed to finally finish off the battery. Initially, I was ready to replace it, but encouragement from colleagues and readers prompted me to try reviving it. Not only did I bring that Prius battery back, but I also resurrected another battery that had been lifeless for over a year.
The Silent Killer: Understanding Battery Sulfation
In my past role writing for an automotive tool review column, I explored many innovative tools. Now, with a collection of project cars and a knack for getting them into trouble, I’m actually using these tools firsthand. Diagnostic scanners, borescopes, specialized connectors – they’ve all become essential. Recently, I finally got to test a battery desulfator and witness its capabilities firsthand.
But first, why would you even need a desulfator? Car batteries, specifically lead-acid batteries, generate electricity through a chemical reaction. These batteries contain lead alloy plates and sulfuric acid, the electrolyte. The lead plates act as the anode and cathode. RS Components Ltd., a battery expert, explains the process:
“The lead plates function as both anode and cathode, submerged in a sulfuric acid electrolyte containing hydrogen and sulfate ions. Negatively charged sulfate ions and positively charged hydrogen ions are attracted to the lead cathode and anode, respectively. When a device connected to the battery is activated, a reaction occurs at the cathode as sulfate ions release negative ions, creating lead sulfate. As lead sulfate levels increase, the electrolyte weakens, and resistance on the plates rises, initiating the flow of negative electrons to the connected device.
As these electrons return to the battery’s cathode, a chemical reaction between hydrogen and lead dioxide on the plate produces water. This process continuously replenishes hydrogen ions alongside the sulfate acid within the battery, allowing the cycle to repeat.”
“The specific reactions vary slightly across different lead-acid battery types to optimize them for their intended applications.”
This chemistry highlights a key weakness of lead-acid batteries: they don’t like being deeply discharged. This contrasts with lithium batteries, which are more sensitive to overcharging.
As described in Batteries In A Portable World, batteries in high-discharge applications like golf carts often have shorter lifespans. While these deep-cycle batteries are built with thicker plates and higher capacity for demanding charge cycles, they still endure significant stress.
Sulfation is a major culprit in battery degradation. The textbook explains it further:
“What is sulfation? During normal battery usage, small sulfate crystals form, which is a natural and harmless process. However, when a battery remains in a discharged state for extended periods, this amorphous lead sulfate transforms into a stable crystalline form and deposits on the negative plates. These larger crystals diminish the battery’s active material, which is crucial for battery performance.”
“There are two types of sulfation: reversible (or soft sulfation) and permanent (or hard sulfation). In the early stages, reversible sulfation can often be corrected. This involves applying an overcharge to a fully charged battery using a regulated current of about 200mA. The battery terminal voltage should be allowed to reach 2.50–2.66V/cell (15–16V for a 12V battery) for approximately 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) during this process can further aid in dissolving the crystals.”
“Permanent sulfation occurs when a battery remains in a low charge state for weeks or months. At this point, restoration is generally considered impossible, although the exact recovery potential isn’t fully understood. Surprisingly, even new lead-acid batteries can sometimes be fully recovered after prolonged periods of low voltage. Other factors might also play a role in this recovery.”
Reviving Dead Batteries for Tool Power: The Desulfation Solution
When faced with a dead car battery, typical solutions include jump-starting or taking it to an auto parts store for charging. Sometimes, you get lucky, and the battery bounces back. Other times, like with my Prius battery, it might take a minimal charge but remain essentially useless. In the past, aggressive charging attempts even led to a battery overheating and boiling – definitely not ideal.
After my initial failed charging attempts on the Prius battery, and before giving up entirely, I decided to try a desulfator charger. These devices are designed to deliver the overcharge pulses mentioned earlier, breaking down the sulfate crystals that cause battery degradation.
You can buy standalone desulfators or chargers with a built-in desulfation function. Being budget-conscious, I opted for a cheap 10-Amp Yonhan charger with a repair mode, costing only $26.99 on Amazon. Reviews suggested it could successfully revive batteries.
My first test subject was the Prius battery. After a day on a regular charger, it only held a dismal 2.89 volts. Connecting it to the Yonhan charger, it surprisingly indicated “full” within minutes. I then selected the repair mode.
In repair mode, the Yonhan unit displayed “PUL,” signaling pulsed charging. Monitoring the voltage, I observed it cycling up to 16 volts momentarily before dropping back to around 12 volts, repeating this cycle continuously.
Initially, the charger read the battery at 80% charge, but after four hours in repair mode, this dropped to 20%. I continued the process for a full day, and gradually, the charge capacity increased. Following the manufacturer’s warning, I checked for overheating; the battery warmed up but never excessively.
After a day of desulfation, the Prius battery reached a respectable 12.8 volts! Encouraged, I moved on to an even more challenging case: a completely dead Everstart battery.
As Batteries In A Portable World notes, the longer a battery remains dead, the harder it is to revive. This Everstart battery had been dead for over a year. It was so lifeless that my regular chargers couldn’t even detect it.
This battery, an OEM size, had become so defunct it was literally being used as a bed frame support!
Could it be resurrected? To trick the Yonhan charger into recognizing the 0.0-volt Everstart battery, I used a jump pack in-line. Again, the Yonhan quickly claimed “full charge,” despite the battery’s true state. Switching to repair mode, I let the desulfation process work its magic.
The Everstart took about two days to reach the charge level of the Prius battery. Over the next week, I alternated charging both batteries on the Yonhan, and both showed progressively higher charges and capacities.
Important Safety Note: Battery desulfation can release toxic gases. Manufacturers warn about this, so it’s crucial to desulfate batteries in a well-ventilated area, away from children and pets. I kept my setup outdoors.
After a week, I removed both batteries and let them sit for a weekend. The Prius battery held 12.7 volts, and the Everstart 12.6 volts. I was amazed, especially with the Everstart, which no other charger could touch.
Voltage is just one measure, though. The real test was performance. I installed the Everstart in my Smart car on a cold morning, and it started instantly, like a brand-new battery. The Prius battery, connected via jumper cables, also started the car without issue.
Building a Car Battery Bank for Tools: Practical Considerations
While revived batteries might not be as good as new, they can be perfectly suitable for less demanding applications, like powering tools. Creating a car battery bank for tools is a great way to repurpose these batteries and gain a portable power source for your workshop, garage, or even outdoor projects.
Here’s how you can think about using desulfated car batteries for tool power:
- Identify Suitable Tools: Consider tools that run on 12V or can be adapted to. This might include:
- Work lights
- Portable fans
- Soldering irons
- Small power inverters (to run low-wattage AC tools)
- Car accessories (like tire inflators)
- Battery Configuration: You can connect batteries in parallel to increase capacity (longer run time) while maintaining 12V. For higher voltage tools, you would need to connect in series, which is more complex and requires careful management. For tool banks, parallel is generally safer and simpler.
- Connections: Use heavy-gauge wires and secure connectors suitable for car batteries. Battery terminals and clamps designed for automotive use are readily available.
- Enclosure: Consider a sturdy enclosure or box to house the battery bank, providing protection and making it portable.
- Charging and Maintenance: You can recharge the battery bank with a standard car battery charger or a solar trickle charger to maintain charge when not in use. Regular desulfation, even after revival, can help extend the battery’s lifespan in this new application.
- Safety First: Always handle batteries with care. Wear safety glasses and gloves. Ensure proper ventilation during charging and desulfation. Avoid short circuits.
Limitations and Expectations
It’s crucial to remember that even with desulfation, you’re not getting a brand-new battery. As Batteries In A Portable World points out, permanent damage from sulfation is inevitable, especially in batteries that have been deeply discharged for extended periods. The extent of damage varies.
My revived batteries are still four years old and have been through significant abuse. A desulfator won’t magically make them new. However, it can restore enough functionality to make them useful again, especially for less critical tasks like powering tools.
As MotorTrend found in their desulfator test, even after two weeks of desulfation and achieving a 13.1-volt charge, restored batteries are not fully rejuvenated. However, they can provide months of additional service.
My advice? If you want to experiment with battery restoration and create a car battery bank for tools, invest in a decent quality charger with desulfation capabilities – perhaps something more robust than my super-cheap Yonhan model. While the Yonhan worked, its build quality is questionable.
For critical applications where reliability is paramount, a new battery is always the best choice. But for DIYers and budget-conscious individuals, reviving a dead car battery and repurposing it into a car battery bank for tools is a worthwhile experiment. It’s a chance to learn about battery technology, save money, and give a second life to something that would otherwise become waste. So, next time a car battery dies, don’t automatically discard it – consider bringing it back from the dead and putting it to work!
