Alum Pb batteries

Re: Alum Pb batteries

Cariboocoot wrote: »

Welcome to the forum Robin.

I think you answered your own question:



Any solution that is either acidic or alkaline can be used as an electrolyte. How effective it is, both in terms of action and economics, is another matter.

For example there are such things as aluminium-air batteries, but most people would not pony up the money or deal with the issues. Lithium batteries have had the same issues, but are getting better. Sometimes it isn't the science at fault but the economics.

Almost all of the sites I visited including Hasselberg, are of a speculative nature and technically illiterate - to be blunt. All shy away from quoting real facts and comparative test results. Many are trying to sell fancy chargers called Tesla or Radiant or Pulse at inflated prices or some snake-oil additive that miraculously cures your dead battery battery.

We all know that any two dissimilar metals/compounds will produce a voltage when immersed in a conducting fluid eg CU and ZN in a glass of tap water (with a tiny pinch of salt to improve conductivity - which is why your food tastes better btw). How well this will function as a battery depends many factors and the chemistry begins to lose me.

Back to our deep cycle Lead acid battery (LAB). Clearly for starters there is a conflict of interest between manufacturer and customer Specific life (No of Cycles) and longest usable life. For example cheap batteries are made from very thin plates and these are crammed into the very bottom of the battery compartment. This leaves no room for the inevitable accumulation of shedded plate material and this soon shorts out the cell so its useless. Early Plante cells seen in glass jars alway had plenty of draft at the bottom of the jar. Also they were designed so you could easily pull the plate pack out for cleaning and reconditioning. Many of these cells have lasted 50-70 years - wouldnt the PV man be delighted with this kind of service. If plate shedding is one of the failure mechanisms, then why not arrange the plates horizontally? Is this just too obvious?

ALUM there are several different types available which have been tried - Potassium Alum, Sodium Alum, Ammonium Alum. No one quotes any comparative figures but they all work (allegedly) with Ammonium being the favourite. They are all cheap. Epsom salts mg sulphate is used to reduce the electrolyte conductivity but its only a short lived fix as the ions get taken up on the plates. So the experimenters claim that a badly sulphated battery can be recovered by swapping the acid electrolyte for saturated alum solution (almost a paste in one video. They then go on to claim that the battery runs good as new (but for how long?) and doesnt suffer sulphation and can be deep discharged down 80% without damage Some claim years of extra life, but nothing is backed up by any credible figures. All too good to be true? Why arent we all doing it?

I was hoping that maybe some PV guy had tried this on his old battery bank

I havent found any credible scientific discussion on this

As a last resort I will go back to basics and start with some 4" squares of lead sheet in a jar and make some comparative measurements, try creating the sulphation problem and see what alum does

BTW all the youtube vids on the subject are presented by delusional charlatans. None of them makes any attempt to measure battery Ah capacity (ie measuring current vs time rather than voltage) fundamental error from the mentality of 5 year olds IMHO.

So Im hoping someone in the PV community can enlighten me

Robin

Re: Alum Pb batteries

BB. wrote: »

Yep--More or less, almost all I have visited are thrilled that the battery "accepts" charging current and is not "dead" 24 hours later. Virtually none go on to measure anywhere near standard battery performance tests (connect an AC inverter to an electric heater or bank of lights, and run the battery for 10 or 20 hours and see if the battery has 5%/50%/100% of original AH capacity. Only a very few even say that the battery is still being used 1 year later.

-Bill

A healthy dose of scepticism is ok with me. I am a retired professional engineer and I wish to see if there is a trace of useful practice that can be gleaned from all the hokum. I will offer to publish my test results in a scientifically accepted manner (no BS). I have an interest in recycling deep cycle batteries used in mobility scooters.

You PV guys have a particular problem cos of the nature of your solar availability. You will be aware that LABs hate being half discharged and partially recharged for long periods. Its a recipe for early hard sulphation. How do you guys deal with this problem if you dont have grid. Firing up an expensive diesel alternator to fully recharge your batteries for say 10 hrs cant be the answer. It must be one big headache?

Most of the work done on LABs never seems to involve dismantling the battery, so what ever they think they are doing is highly speculative. Agreed this wont work for automotive batteries cos of their flimsy construction, but stationary batteries that havent been abused? Forklift batteries are frequently dismantled and reconditioned. Of course how they actually do it is a closely guarded secret, but not too difficult to guess.

One of the big cons in the EV market is the use of gel cells or AGM cells with VLRA valve release. Supposedly the gases recombine to make water. Well I have just resurrected a 40Ah gel cell which had gone dry. I topped it up with rain water + small qty epsom and its on its third charge discharge cycle and I get ca 30Ah on C20 rate. This is supposed to improved with cycling. Prior to this the cell was dead and wouldnt accept a conventional dc charge. I zapped it with a square wave pinger up to 60v for half a day. With the added water it suddenly seemed to come back to life. I will publish the graph 15.5 hrs @2A down from 12.5 to 10.5Vdc

If this really works, there has to be something in it of use cos Ive just saved myself £100 for two batteries (the other one wasnt so bad.

So guys, be sceptical, find fault with my methods - most welcome and I am not selling anything BTW

BTW I hope you all know that distilled water has a very high resistance ca 20Mohm-cms
http://forum.allaboutcircuits.com/showthread.php?t=18893
but this fall rapidly with the minutest amount of impurities added such as common salt

He might be right about electrocution greater in pure water, but in practice you never get really pure water for very long (it wont boil for a start)

You can get an electric shock from a 12v battery in a marine wet environment - try it - wet you hands with very salty water and swipe your knuckles across the terminals

Cheers

Robin

Re: Alum Pb batteries

PNjunction wrote: »

Already done by tightly wrapping tppl into spirals, or high compression of flat-plates. Enersys, Hawker, and even Optima can tell you all about it. 1985 time frame.



yep - back to 1998 or so when LAB (agm specifically) for EV was vying as a competitor to nimh. Required an IUI charge profile for 80-100% DOD, which no consumer had on hand, nor was available for purchase in decent numbers.



Why waste your time? You can avoid sulfation in it's entirety by going Li-ion. Choose your sub-chemistry for safety, which is currently LiFepo4. One reason you can have it under your motorcycle seat. Hobbiests may use the wrong chemistry and give li-ion a bad name because they are taking risks with anything more energy-dense and unstable than lifepo4. (Like Lico02 chemistry).

Experimentation is good, even for 'ol lead-acid. But if there is nothing but talk, and nothing brought to market, it doesn't matter. Most of the talk is usually an endless thread of opinions, or weak attempts to disguise themselves as seed for investor pitches.

Many so called new battery discoveries, are merely a way to stuff a patent-portfolio warchest, with no real intent on producing the product brought to life in the lab.

I cant fault your logic sir, but for one issue - the environment.

Having these LABs deliberately engineered to fail and end up as scrap is surely unacceptable. The LAB is likely to remain by far the cheapest form of electrical storage. Lion is 10x cost so far
If it is possible to recondition stationary labs particulary for PV use then there has got to be value in pursuing this line - given so much BS to clear out of the way once and for all.
For my use the wet cell is half the price of a gel cell and much better suited, but try and buy a deep wet cell for EV use? I am working on it. Just because I believe there's a conspiracy, doesnt make me wrong.

I'll bet there are many PV guys out there who would love to hear a proven method to recondition their failing battery banks. Think - the Pb doesnt go anywhere or evaporate. Its still there to be re-used
I remind you all, I am not selling anything. In my area of mobility scooters, the market is chock full of cowboys charging 5x the true price on naive seniors (same applies to golf carts)

For example my electric bike's lion cells and showing age after 4 years, maybe down to 60% but still useable for my short journeys. A new battery pack costs nearly £500 which is half the cost of a new bike. I can re-cell the battery pack myself with AA cells from ebay for ca £100 so you see the gross markup (rip off) involved

BTW, often misquoted, but Pbsulphate is poorly soluble in water but interestingly it is soluble in caustic soda? and of course EDTA

The conspiracy thickens

Robin

Re: Alum Pb batteries

WARNING

On a related topic, switched mode power supplies. I have just trashed two of these with the same fault. They somehow lose volt control and over load themselves blowing the fuse. There is no output from either now and I havent time to bury into it. They were cheap PRC shoddy goods 10-15 Vdc @8A. More than enough to cope with a 12V 40Ah battery. Well something goes wrong with the control circuit cos is deal with the back emf of the battery and this seems to throw it. Its normally used for powering strings of led lamps, obviously a passive load supplied with constant voltage. Its supposed to have a current limiter but obvioulsy doesnt work with a 12 back emf. I havent got my head round the cct yet but have my suspicions

I just thought Id post this as a caveat to others. BTW my bench psu isnt too happy charging a 12 v battery. It has gone into uncontrolled mode on two occasions, belting out 50vdc with no adjustment possible. I managed to reset it by shorting the output momentarily - drastic, but it worked. It too is a cheap PRC piece of junk.
Clearly Im not confident in leaving such unattended, might cause a fire

Cheers

btw I was only charging at 2-3A CV @ 14v but it somehow ran away with itself

Robin