# Reviving Your Dead Battery



## ThaMule (Jan 26, 2010)

I went out to crank the brute force today and my battery was dead. I figured it would be because it has been a long while. It happened to be more than I had thought. I measuring 6.5V. I broke out my CTEK 3300 charger and it immediately went into desulfation mode. So with that being said. This is going to be a "How To" for reviving your dead battery. 

Battery sulfation takes place when a Lead Acid Battery discharges beyond a certain voltage that is rechargable with a regular charger. The lead from the plates combines with the electrolyte (dilute sulphuric acid) to make lead sulfate. When the battery is recharged this process is reversed however, some of the lead sulphate will crystalise on the lead plates. The deeper the battery is discharged, the more the lead sulphate is likely to crystalise acting as an insulator and reducing the plate area in contact with electrolyte. Over time this build up of lead sulphate crystals will kill the battery.

Reconditioning a Lead Acid Battery
Desulfation (also know as Reconditioning or electrolyte stratification) offers a way for dead batteries to be brought back to life and for tired batteries to be rejuvenated. Desulfation will not bring batteries with a shorted cell, or worn out plates back to their former glory, but it is a valuable tool for anyone depending on battery storage for power who cannot afford to buy new batteries.

When lead sulphate crystals build up on the lead plates, it is not an easy task to remove them and thereby recondition the battery. As more and more crystallisation occurs, the voltage required to shift the crystals (dissolving them back into the electrolyte) also increases. But, if you were to put a constant high voltage through the battery it would overheat and could potentially explode. Pulse conditioning is therefore used to ensure that only the sulphate crystals are affected and the battery does not overheat.

Every lead acid battery has a resonant frequency at around 2 to 6 megahertz. If sufficiently pulses of electricity (high frequency, high voltage, but low power) are sent into the battery, rhythmic beating (resonance) of the plates causes the crystalline deposits to break up and the sulphate returns to the electrolyte solution. This process can take a matter or weeks during which time the battery must be trickle charged (in parallel with the desulphator) so that the battery ends up reconditioned and fully charged.
Note that the voltage measured across the battery terminals will drop as the desulphation takes place as the internal resistance of the cells is reduced by the clearing of the crystals on the lead plates.

You can build DIY battery desulfator circuit. Here are some links on how to do so. 

http://home.comcast.net/~ddenhardt201263/desulfator/lowpower.htm

http://screwdecaf.cx/mini-d.html

If you are not comfortable with building your own you can buy chargers that have the capability of doing so. I personally own a CTEK Multi US 3300. It works great and are among the best chargers in the world. Here is a link to their website. 

http://smartercharger.com/

Another method to recover a deeply discharged battery is by placing another battery in series between the charger and dead battery. Here is a link to an Optima tutorial on how to do so.






Please feel free to add to below and I will update the main post with all the new info.


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