Once a battery is too old it is past due any rejuvenation including those methods that work. As batteries age they get sulfated, sulfate build up increases internal resistance on the cells thus decreases charging effectiveness and cranking ability which we usually attribute to a battery that is on its way out. As sulfate crystals grow, they become larger and harder to break into electrolyte through charging, hence why everyone here recommends buying the freshest batteries possible.
All batteries suffer from sulfation, even the good ones we may have bought one year ago. One way to evidence this is that a battery will tend to lose its specific gravity over time, it starts with 1280 when fresh in the factory, but because of sulfation specific gravity will steadily decrease over time until a battery is rendered useless down the road. Anyone who will measure a battery in good standing condition after about two or three years of use should see a drop in the specific gravity reading.
When batteries become sulfated, the sulfated crystals grow on the plates causing them to expand. This expansion causes the plates to buckle as they are already sandwiched into the battery under pressure to minimize vibration. The plate still expands, but since it has nowhere to go it buckles into a wave like form which can be observed on old or discharged batteries. Buckling is nothing more than mechanical stress which causes permanent damage to the plates, hence why old batteries cannot be rejuvenated.
In my opinion, there is no such thing as rejuvenating old batteries, one can only maintain a good battery to extend its life. One product which I have been using over the past 8 years is a device mentioned here made by pulsetech, many people don’t like then here for one reason or another, but through my measurements I have been able to confirm that their products do what they claims to do. No matter which pulsing product you use, the idea is to have something attached permanently to your battery to help it break some of the more stubborn sulfate crystals so that the battery can be charged to nearly 100% and its specific gravity can be near 1280.
One other thing to remember is that no desulfator will be able to do its work over a day or two, rather it is a gradual process which takes over months and months. This is from a personal experience by buying a car which sat on a lot for many months. Initially I thought that the battery was shot with no increase in specific gravity over one month only to find out that this battery was so badly damaged that the desulfator needed 6 months to bring it back to near normal state.
All batteries suffer from sulfation, even the good ones we may have bought one year ago. One way to evidence this is that a battery will tend to lose its specific gravity over time, it starts with 1280 when fresh in the factory, but because of sulfation specific gravity will steadily decrease over time until a battery is rendered useless down the road. Anyone who will measure a battery in good standing condition after about two or three years of use should see a drop in the specific gravity reading.
When batteries become sulfated, the sulfated crystals grow on the plates causing them to expand. This expansion causes the plates to buckle as they are already sandwiched into the battery under pressure to minimize vibration. The plate still expands, but since it has nowhere to go it buckles into a wave like form which can be observed on old or discharged batteries. Buckling is nothing more than mechanical stress which causes permanent damage to the plates, hence why old batteries cannot be rejuvenated.
In my opinion, there is no such thing as rejuvenating old batteries, one can only maintain a good battery to extend its life. One product which I have been using over the past 8 years is a device mentioned here made by pulsetech, many people don’t like then here for one reason or another, but through my measurements I have been able to confirm that their products do what they claims to do. No matter which pulsing product you use, the idea is to have something attached permanently to your battery to help it break some of the more stubborn sulfate crystals so that the battery can be charged to nearly 100% and its specific gravity can be near 1280.
One other thing to remember is that no desulfator will be able to do its work over a day or two, rather it is a gradual process which takes over months and months. This is from a personal experience by buying a car which sat on a lot for many months. Initially I thought that the battery was shot with no increase in specific gravity over one month only to find out that this battery was so badly damaged that the desulfator needed 6 months to bring it back to near normal state.