Charge, Dump & Desulphation

R

rWAVE

Member
As I continue to get my arms around my solar / wind hydroponics project, use of charge / dump controllers to manage my 12 Vdc battery becomes the next order of business.

Continuing my Internet education yielded a very simple dump controller circuit at Hurd Solar - redrawn below for clarification - and simple enough to warrant further experimentation.

However, I was really intrigued by what I found at a small, French company TuneCharger, and their proof-of-concept prototype (MTC4.3) you can purchase (datasheet or Technical Reference Manual). You can also purchase their proprietary PIC chip and design your own circuit. In addition, check out their other commercial products at Bat4Life for battery rejuvenation - sorry, French only :(. Although interested in testing their MTC4.3, the US$/Euro conversion left me in shock!

However, reading the Technical Reference Manual led to desulphation. While the science behind sulphation is fairly well understood, how well is desulphation known (i.e. do the various desulphation implementations really work)? I ask because my "plan" is to acquire via donation a pair of 6V spent golf-cart batteries (probably one of the very best choices) and attempt some degree of "rejuvenation", since the capacity of these batteries greatly exceed my needs.

Also, an international friend indicated to me recently that a desulphation circuit appeared in the February 2003 issue of Silicon Chip - which I don't receive - and I was curious if anyone had seen or built this circuit? If some success with desulphation is possible, the MTC4.3 looks more attractive in spite of the cost.

Thoughts, anyone?

Richard
 
M

manuka

Senior Member
SiChip have had quite a number of such circuits, & I believe the May 2006 teaser => www.siliconchip.com.au/cms/A_106633/article.html is their most recent. Naturally such articles are strictly copyright to SiChip. Tried your local library? Where are you?

As desulphation cures (both chemical & electrical) are lumped in with snake oil by many,first consider a VERY wide view of the matter! Maybe look for awkward/heavy batteries (although their present scrap value is now quite high) that others can't be bothered taking in for scrap. Electric forklift types especially are a real hassle to move, although many of them are given a rough life & plate buckling etc is common.

EXTRA: How much energy do you wish to store? Many security firms toss out near new 12V 7Ah SLA batteries as part of an annual security audit on critical installations! These brick size darlings make magnificent general energy stashes- often free if you ask nicely. I've used such SLAs for decades educationally & typically get 5-8 further years out of them.
 
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R

rWAVE

Member
Thanks for the comments. :)

Here in SoCal, I get plenty of sun for the PV and only a few puffs for the turbine. Hence, the turbine is basically for demonstration purposes, providing little charge potential throughout most of the year. We do get Santa Ana winds, though, so a small percentage of my harvested energy will come VERY sporadically, but usually throughout the night.

BCJKiwi, I did a fair amount of reading on battery technology and the care and feeding of same. Obviously, cell shorts and other use abuses reduce the chances for sulphation reversal. But many studies show SOME success, which is encouraging.

Didn't realize Silicon Chip had so many projects on this subject in recent years; maybe a bit more useful than "snake oil"? ;)

I've been to many public libraries and bookstore locally looking for issues of Silicon Chip and have NEVER found it! :( If someone could point me to a local source . . .

My energy needs are modest; I have a 35W AC pump that is turned on between 0 and 8 times per day, with each on-cycle lasting between 4 and 10 minutes.

I chose using a pair of 6 Vdc golf cart batteries because 1) they are GREAT batteries for energy storage - and I can lift them - and 2) there are dozens of courses locally and I have contacts at many of them.

Manuka, THANKS for the tip on security firms; never thought of that!

Richard
 
D

Dippy

Moderator
A slight aside:-

I've been doing a lot of work on solar charging recently and drew on information linked from this Forum and would like to thank the contributors.
In addition I studied the information from a contributor called Desulfator and got sound advice from BeanieBots.
I also spent many hours pouring over battery manufacturer Data Sheets concerning charging techniques.
I also ended up with about half a ton of batteries in various conditions to try out and ended up with code that can make a reasonable estimate as to the condition of the battery.

In summary I'd say Desulphating works, with caveats.
1. Without analysis of the battery I'd say that some people jump to the incorrect conclusion that sulphation is happening. I've devised my circuit and code to keep an eye on the impedance change in the battery over time.
2. Take note of what BCJKiwi says above.
3. Be more careful with your Desulphation circuitry / code than a lot of circuits are. It is easier to over-cook than people say.
4. Not all lead acids are the same. (This is obvious but often ignored).
5. Don't expect miracles. Your revitalising will vary from nothing to something.
6. My personal opinion when designing a super-charger; start off with a new battery so you know it's history.

I wish I could call my device the Lazarus Battery Conditioner, but it ain't that good!
 
B

BeanieBots

Moderator
Yes, desulphating does work. However, and this might sound stupid, it only works on batteries which have been sulphated!
Most batteries which have been kept on float charge for years such as alarm backup, are usually cooked by high voltage and have become oxidised. Oxidation is non-reversible. Batteries which have been left unused for many years and 'appear' to be almost open circuit (that is, won't take any current at 14v or so terminal voltage) are usually sulphated and can be rescued back to give at least 75% of their stated capacity.

A very simple explanation is as follows:-
The sulphate is an insulator. It is very thin and can be jumped by high voltage. Once conduction starts, the sulphate breaks down. The problem with simply applying a high voltage is that it will cause oxidation. By applying a series of very high 'spikes' to the terminal, the sulphate can be breached but without enough time to cause electrolysis and hence oxidation.

There is actually a forum dedicated to the subject!
Can't remember the URL but a google on "sulfation" should find it.
 
D

desulfator

Senior Member
Desulfation

A number of posts are on this forum should you search for "desulfation"

Basically desulfation techniques work well on lead acid batteries that have sat with an incomplete charge or those that are never charged completely (AE systems with inadequate charge capability or automobiles that are frequently used in short trips)

LA batts used in emergency lighting and power systems normally are cooked by the float voltages set too high.



A desulfation forum can be found at,

http://leadacidbatterydesulfation.yuku.com/



Our main website URL has been changed to,

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