‘A group of back yard experimenters are looking at ways to rejuvenate used sulfur lead acid batteries by replacing the electrolyte with pickling alum, as well as magnesium sulfate (epsom salts), and even copper sulfate. It is thought that the new electrolyte reverses the sulfation build up on the plates of the battery.’
by Timothy R. Shell
Augus 2, 2010
A group of back yard experimenters who have been working with lead acid battery conversions over the past several years have now completed the first test of the use of a copper sulfate solution as an alternative electrolyte.
Past work has focused on using pickling alum, (aluminum sulfate/potassium aluminum sulfate), as well as magnesium sulfate, (epsom salts), as the transition chemicals of choice. While the exact chemical reactions which occur when the electrolyte of a lead acid battery is replaced with an alum or other sulfate is not crystal clear, the conversions are widely accepted as very successful. Replications of this technique have been countless. It is assumed that the new electrolyte reverses the sulfation build up on the plates of the battery.
The process is simply to dump the original electrolyte out (dispose of safely), and refill with the new electrolyte solution, and recharge the battery as usual. Sometimes, depending on the state of decay in the unit several charge cycles are necessary to revive the unit. Converted batteries show a different performance curve than normal lead acid batteries, with top resting voltage around 11.6v instead of 12 or more.
Our group has been disseminating this information and learning together. We are excited about the ability to take nearly dead SLA batteries and give them extended new life.
The happiest part of the equation is the economics. If a car starting battery which costs, what? $70USD, is about to be replaced, perhaps for the price of several ounces of alum (less than $5.00) and an hours work the battery, can be returned to service for several years, the savings are major.
We hope that everyone will learn this simple technique to save money in hard times.
Another economic dynamic of this technique is that it directly affects the cost of operating an EV to the point that lead acid batteries become and economically acceptable candidate for battery power. It is possible to operate the EV with lead acid batteries up to the point of near failure on the original life cycle, and then convert them for an additional life cycle. This battery cost savings is huge in this case, and dramatically reduces the cost per mile of operating and EV. Whereas a gas powered vehicle primarily needs to price fuel to compare cost/mile traveled, EV’s need to primarily price replacement batteries to make the same calculation. If the life cycle of the batteries of the EV is doubled at a fraction of the original cost then this creates a major cost reduction per mile traveled. Thus this technique can launch SLA EV’s into the cost effective transportation category without having to wait any longer to find better batteries.
Recently one group member successfully tested copper sulfate as an alternative electrolyte, expanding the options for available products with which to restore used lead acid batteries.
Further information can be found at http://tech.groups.yahoo.com/group/batteryconversions/
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