I have been working with used/old/discarded lead/acid batteries for about five years with the aim of making them work again.
At the moment I use homemade electronic desulphators built from scrap I find in the dumps at electrical stores.
I use varying amounts of power depending on the battery. Size is the most important indicator of the amount of amps at each pulse it should receive in order to remove the hard sulphate crystals. over 100 A at 50 milliseconds is nothing unusual.
After a year or so messing with various chemical and electrical methods to rejuvenate batteries I was able to get an ”’average”’ battery back to usable condition in a few weeks to a month.
These days I can have a five year old car battery which sported electrolyte with a SG in the region of 1100 – 1150 ready in two or three days, and using ideas learned from each electronic pulser I’ve made I’ve got the desulphating down to 12 hours for a 40 A/h battery fairly reliably.
There is no doubt that electronic desulphating works, but I have tested one store-bought desulphator and found it was about as good as leaving some sulphated battery on a float charge – It was useless as far as I was concerned.
I’ve made nine or so electronic desulphators. These days I use transistor blocks from old air-conditioner circuit boards for the pulse. I drive them with a two-transistor astable multivibrator. I’ve rebuilt a couple of them so I’ve got seven which I can use.
But I’m retiring at least one of them as it isn’t much good compared to the newer ones I made which I improved by learning from it.
I’m going to make at least one more. It’s going to be the most powerful I’ve made. The most powerful one I’ve got uses a transformer from a bench-top arc-welder and has about 30,000 mFds of caps being pulsed into 24 V at over a hundred amps (if I so choose). It will go higher but at some point the transistor blocks are overloaded and they short – But I sometimes test it on a couple of hundred amps before I turn it down.
That powerful charger is currently doing two 155 marine batts in series. They’ve been pulsed for a week and the cells are now up to max level and the electrolyte measures within the green zone of my hydrometer. (Used to take me at least a month to do batteries that size).
… I’ve got a pair of Hitachi 210 marine batteries which I could ‘do’ with that charger, but I’m really itching to make that new one which will easily deliver a couple of hundred amps into those batteries. I’ve got all the parts but I’d like some more caps. i get my caps from air-conditioner pc boards as well and there are only three largish ones with each board. Perhaps as summer is approaching I’ll harvest a few dozen so I can get that big whack I just know does the job.
A quick note about the reviews on this site: I am an affiliate for every product I review. The vendors of these products give me them without charge in order for me to test them. However all my reviews are done as honestly as possible and I make no promises to the vendor prior to writing my review. Should you click a link on this site that takes you to a paid product this link will be an affiliate link and I will be paid a percentage of the sales price should you decide to purchase that product.