Many car owners face the frustrating situation of a dead 12 volt car battery. Instead of immediately replacing it, there’s a DIY method you can try to revive it, potentially saving money and extending the battery’s life. This approach, based on a personal experiment, explores the possibility of repairing lead-acid batteries using a pulse charger and electrolyte adjustment.
In this experiment, two old 12V batteries, initially showing only 4.5V, were tested. The process involved slow charging and discharging to assess their capacity. One battery showed a very low capacity of 402mAh, while the other performed better at 4424mAh. To attempt repair, both batteries were opened, and the electrolyte was replaced with sulfuric acid sourced from an old lead-acid battery, instead of distilled water.
A homemade pulse charger was then employed. This charger, built with a 555 timer and MOSFET, delivered 18V pulses up to 10A at a 1kHz frequency with a 1ms pulse duration. The battery with the extremely low capacity showed signs of a bad cell, failing to charge beyond 10V. However, the second battery, after two days on the pulse charger, showed a significantly improved discharge capacity of 6682mAh. This was a notable recovery for a 4-year-old SLA battery.
The same pulse charging method was also applied to a 12V 3Ah motorcycle starter battery. After several charge and discharge cycles, this battery regained enough performance to start the engine and maintain a decent charge rate.
While this DIY repair method showed some success, it’s important to note that results can vary significantly. In the experiment, one battery remained unrepairable, even with pulse charging. Attempting to revive it with a simple 12V transformer and bridge rectifier only resulted in overheating and further voltage drop, indicating irreparable cell damage.
The effectiveness of pulse chargers or desulfators remains debated. However, this experiment suggests they might aid in reviving some batteries. If a battery is beyond physical repair with damaged plates or degraded electrolyte, these methods are unlikely to work. In such cases, replacement is necessary. Even with successful revival, the battery’s capacity might not fully return to its original specifications, and performance will vary.
In conclusion, attempting to repair a 12 volt car battery is possible, and pulse charging may offer a chance of revival. However, outcomes are unpredictable. If your battery is severely damaged, replacing it remains the most reliable solution. Consider this DIY approach as an experiment with potential benefits but no guarantees.
