Battery Desulfation
Battery Desulfation
Find out how to desulfate/desulphate and rejuvenate lead acid batteries
storage | electronics
Battery
sulfation takes place when a
Lead Acid Battery discharges. 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.
Build a Battery Desulfator
A DIY
battery desulfator circuit originally published in the US-based
Home Power magazine has been successfully made for many years all over the world. Here are links to the instructions to build the
Low Power (circuit design above, and finished example circuit pictured below) and the
High Power versions of the circuit. These links are to be found together with a lot of other useful information
here.
For more infomation about
battery desulfation, click here to visit the very useful
Lead Acid Battery Desulfation Newsgroup. Also try this link to Mikey Sklar's
Mini-D 12V battery desulfator, and his second generation
battery desulfator with the addition of a display and data logging.
Article Last Modified: 16:56, 5th Oct 2009Comment on this Article
If you have any comments on this article, please email them to
neil@reuk.co.uk.
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