I was watching this video on YouTube about refreshing old batteries and restoring their operational capacity. I am looking into stuff like this to take better care of my vehicles and find cost-effective ways to prolong component life.
The method used in this video altered the specifics of the battery and increased its CCA. Will changing something like that damage a car if reinstalled? Is a hydrometer a useful tool to monitor battery life? Is this kind of service useful or just swap the battery?
Not worth it. Replace the battery
It's best to prevent sulfation from forming on the battery plates, instead of trying to remove the sulfation after it's already formed. The easiest way to prevent sulfation is to always keep the battery fully charged at 12.6+ volts. Even at 12.4 volts the battery is 80% charged and will begin sulfation. A battery at 12 volts is only 50% charged and will likely cause accelerated sulfation.
Lead-acid batteries will weaken if they are left for days at less than 80% charge, even deep cycle batteries. Their active material (the parts that store electricity) goes inert if they’re left discharged too long. That’s called sulfation and essentially it cuts into how much power a battery can store.
Sulfation is the formation of lead sulfate crystals on the plates inside the battery. Have you ever seen a corroded battery terminal with blue/green/white powder all over it? That's lead sulfate crystals and the same thing happens to the lead plates inside a battery if not kept fully charged.
https://www.crownbattery.com/news/sulfation-and-battery-maintenance
Project Farm has done battery restoration testing. It basically involves overcharging a battery until the water inside it starts to boil in an attempt to remove sulfate crystals from the surface of lead plates.
Obviously overheating a battery until the water boils is also damaging the battery and I doubt a restored battery is going to last very long even if the restoration process works. A brand new battery that's well taken care of only lasts around 5 years.
A good way to test a battery is putting it under a heavy load such as cranking the engine over and checking how much the battery voltage drops with a multimeter. If the voltage drops under 10 volts while cranking it's time for a new battery. The battery should be fully charged (12.6+ volts) before testing.
