Lead crystal batteries (at least the ones I'm familiar with) are batteries that use salt crystals as the electrolyte. There are many different crystals that can be used. I have been experimenting with converting lead acid batteries to lead crystal batteries. You can find videos on how to do this on Youtube and at various DIY websites by doing a search. The ones I make are called "lead alum" batteries. I mix aluminum sulfate with rain water or distilled water and use that to replace the acid in the battery. These DIY batteries have a lot of potential for low wattage applications like LED lighting, which is what I use them for.
I've heard that there is one Chinese company that uses a similar technology for batteries used in those little scooters and runabouts, so with the right formula they apparently have much more potential than what I'm doing with them right now. I'm hoping eventually to find a way to use them to run a freezer or refrigerator.
You can get Alum at a local grocery store. It's used for canning pickles. But, to make an alum battery it's too expensive. About $30 to convert a typical car battery in my experience. I order 99.5% pure Aluminum Sulphate that I can get for about $25(US) for 3 lbs on Ebay. I can convert maybe 3 or 4 typical car batteries with that. I estimate it costs me about $7 or $8 per car battery. I'm looking into possibly buying it in a different form cheaper, but until I do some testing I won't go into that.
By converting old junk car and lawn tractor batteries I am now able to run (on some of them) a 5 watt (40 watt equiv) LED bulb that I ordered from China for about $2 every night, all night using a 15 watt solar panel. I'm in Michigan and we get a lot of clouds in the winter and the days are pretty short, but with a 20 watt panel I'm certain that I can do that all year long. I use a photo switch mounted outside to automatically turn the light off and on. With the battery, the bulb, a cheap charge controller and a 15 watt Harbor freight solar panel (from a 3 panel kit) it cost me about $65(US) for this setup, not counting the fuses, which might add another dollar or two. (Actually $55, but I'm counting the $10 I would have gotten if I had returned the battery for a refund of the core charge)
They say these used batteries will last another 10 to 15 years or longer. I have one I've been using to light some smaller LED "Mighty Lights", which have motion and light sensing built in, for the past 3 years.
There is a guy on Youtube who has a video comparing lead crystal batteries to other battery technology for a solar system he was setting up in Africa for his house. He seemed to like the crystal batteries and apparently had a source for ones that can be used for solar. So there's a lot more information out there on this technology, and it looks like it has at least some potential for a battery that is probably a lot safer than using acid, although the lead is still an environmental concern if not disposed of properly.
I have started a discussion group on Facebook about economical alternative energies, and I have some computer data on the experiments that I'm doing with lead crystal batteries if you're interested. I haven't posted any of that data yet, but if someone asks me it will motivate me to post it sooner. Eventually I plan to post some of that data. Especially if someone else is interested in experimenting with it and having discussions about results, practical uses, environmentally safe disposal practices etc. The group is about more than just solar and battery technology. Anything to do with alternative energy and sustainable living can be discussed there.
Here's the link:
Alternative Energy Economics Discussion Group