The first battery I restored came in a diesel van I bought with a blown motor, It had been sitting around for a year or so and wouldn't even turn on the ignition lights. When put on the charger it would simply not charge, and would throw up a fault condition light on the charger. The battery was restored while I fixed the engine and it is still in the van today and it starts perfectly. I'm always fixing cars and have restored another 8 batteries since then, https://reconditioning-battery.weebly.com and they all preform like new. Once you have the voltmeter and solar panel the process is free, so you have nothing to loose. Adding aspirin to the battery is another hack that is often seen in videos claiming to revive dead batteries.
7 Methods to Guard Against does battery reconditioning really work
Battery reconditioning, especially for lead-acid batteries, is a valuable practice that brings multiple benefits.
Benvenuto!
