PowerSwitch Main Page
PowerSwitch
The UK's Peak Oil Discussion Forum & Community
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Making lead acid, or other batteries
Goto page 1, 2  Next
 
Post new topic   Reply to topic    PowerSwitch Forum Index -> Electrical, Theory and Practice
View previous topic :: View next topic  
Author Message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Fri Jun 27, 2008 12:03 pm    Post subject: Making lead acid, or other batteries Reply with quote

Lead acid batteries are widely used for energy storage despite the technology being well over 100 years old.

Present day batteries are the result of 100 years of research aimed at making batteries cheaper or more compact, though in most cases no more durable.
It would not be feasible to make a battery as compact as those sold today, to make it portable would be a challenge.

However the local manufacture of basic batteries is entirely possible.

A simple lead acid cell consists of two lead plates immersred in dilute sulphuric acid.
To maximise capacity, the plates must have the greatest possible surface area, this is often achieved by complex grid patterns
To minimise internal resistance, the plates must as close as possible to each other, but not touching.
Acid resistant materials such as glass fibre, glass rods, or plastic grids are often used.
Alternativly the plates are made to fit into grooves in the container, to keep them apart.

When such a simple cell is first charged, a film of active material is formed on the surface of the plates, when the cell is discharged this turns into lead sulphate.
At first the capacity is very low indeed, it increases with each charge cycle. Before such a simple cell can be put to use, it must be charged and discharged many times, this is known as "forming" (a good use for surplus PV in summer!)

To avoid the time consuming and energy wasting forming process, all modern batteries use ready formed plates, consisting off lead plates on to which the active materials are pasted, or of lead grids into which the active materials are pressed.
The drawback is that the active materials fall of in time, rendering the cell useless
To make ready formed plates is clearly a bit more innvolved, but entirely possible in a local factory.

Lead could be mined in the UK , mainly in the West Country.
Large glass containers to house the cells can be made out of recycled glass, anywhere with basic glass working facilities.
Sulphuric acid is made be a simple process, but requires sulphur, which I dont think is found in the UK.

To make the most basic lead acid cell is easy, I have done it simply to prove the idea
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Blue Peter



Joined: 24 Nov 2005
Posts: 1936
Location: Milton Keynes

PostPosted: Fri Jun 27, 2008 12:26 pm    Post subject: Re: Making lead acid, or other batteries Reply with quote

adam2 wrote:
To make the most basic lead acid cell is easy, I have done it simply to prove the idea


"I've got the acid burns to prove it" Very Happy

What strength (molar) sulphuric acid do you need?


Peter.
_________________
Does anyone know where the love of God goes when the waves turn the seconds to hours?
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Fri Jun 27, 2008 1:01 pm    Post subject: Re: Making lead acid, or other batteries Reply with quote

Blue Peter wrote:
adam2 wrote:
To make the most basic lead acid cell is easy, I have done it simply to prove the idea


"I've got the acid burns to prove it" Very Happy

What strength (molar) sulphuric acid do you need?


Peter.


I dont know. The strength of battery acid is tradditionly measured by specific gravity. 1.25 is about right, though it is not that critical.

Proper care should of course be taken handling battery acid, safety glasses and old overalls being recomended.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Tue Nov 13, 2012 12:56 pm    Post subject: Re: Making lead acid, or other batteries Reply with quote

adam2 wrote:
Blue Peter wrote:
adam2 wrote:
To make the most basic lead acid cell is easy, I have done it simply to prove the idea


"I've got the acid burns to prove it" Very Happy

What strength (molar) sulphuric acid do you need?


Peter.


I dont know. The strength of battery acid is tradditionly measured by specific gravity. 1.25 is about right, though it is not that critical.

Proper care should of course be taken handling battery acid, safety glasses and old overalls being recomended.
Adam, I'd be very grateful if you could point to any links for either the purchase of fully serviceable/repairable lead acid batteries, or a site that gives specific instructions for constructing a lead acid battery from scratch that would then, by definition, be fully serviceable/repairable.
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Tue Nov 13, 2012 3:34 pm    Post subject: Reply with quote

I have a nasty suspicion that fully repairable/rebuildable lead acid cells are no longer available.
Many of the more traditional types look fairly easy to dismantle, but that may not help much. Even if the manufacturers are willing to sell replacement plates, remember that these represent most of the cost.
By replacing the plates, all that is being re-used is a relatively cheap plastic or glass container.

Also I doubt that either replacement battery plates, or complete batteries have a long storage life, even without acid.
Very large batteries are often supplied "dry", that is without acid, but that is primarily to ease transport, not to prolong storage or shelf life.

To make a modern lead acid battery is a fairly innvolved process, certainly feasible for a small industrial concern in a post peak world, but probably not feasible for an individual.
Before the oil age, lead acid cells and batteries were widely manufactured by small companies, with basic machinery.
It was almost unknown for individuals to make their own.

To make a very basic lead acid battery oneself is entirely doable, and the materials keep forever.
A home made cell or battery will be very bulky and heavy compared to those sold today.
It should however last 25 years or more., and be more abuse resistant than modern ones.

In principle all that is required is two pieces of pure lead in a dilute sulphuric acid solution. Two small lead strips and a beaker may be used to demonstrate the principles.
To obtain a useful capacity, a much greater area of lead is required.
To obtain a low internal resistance, the plates must be fairly close together but NEVER TOUCHING.
The thickness of the lead is not that important, too thin will not be robust, and too thick adds needless cost and weight.

A practical small (relatively!) home made lead acid cell could consist of a wide necked gallon glass jar in which the plates are immersed.
Use two long sheets of lead, one for each plate, wound together in a spriral, with some porous, acid proof material between the plates to prevent them from touching.

When cutting the lead sheet into the plates, be certain to leave a long piece protruding from each plate, such that it will be above the acid level in use. These will form the electrical connections.

Fill the jar with a mixture of sulphuric acid and distilled water, with a specific gravity of 1.25 in temperate climates or 1.2 in tropical climates.

When first manufactured the polarity is arbitary, but mark the connections positve and negative to avoid later confusion.

Charge the new cells at about 2.5 volts per cell, and then discharge.
The capacity is very small initialy but improves with each cycle.
A cell in a gallon glass pickle jar might be about 1 AH when first made, increasing to about 10 AH after many cycles.
When fully charged , the positive plate will be a dark chocolate brown colour, and the negative will be silver grey.
When discharged, both plates will be dull grey.

The deposits on the positive plates get thicker with use, and eventually fall off to form a sludge at the bottom of the cell. For this reason the lead plates should not be to thin initialy, or they will disintegrate.
The sludge that slowly builds up in the bottom of the cell will short circuit the plates if it touches them. Therefore the plates should be supported clear of the bottom of the jar, perhaps on small glass strips.

Any other design may be adopted as desired, remembering the principles of greatest surface area, no short circuiting by sludge deposits, and keeping the plates fairly close but never allowing them to touch.
Add distilled water as needed, and at very long intervals add more acid if the SG has dropped.

Discharging or charging too fast tends to dislodge the desireable deposits from the positive plates and should therefore be avoided.

6 cells such as I describe would be a bulky and costly affair, remembering that a 12 volt 7 AH sealed battery fits in one hand and can be purchased for less than 20.
OTOH the materials for the home made battery keep indefinatly, and the assembled battery should last 25 years or more.
Such a battery, and a PV module, and some low power LED lamps could light a house almost indefinatly.

Even a home made battery can deliver a suprising current, and should be protected by a fuse.
Take great care in handling the acid.
Lead is fairly safe provided that you dont eat it.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Tue Nov 13, 2012 3:57 pm    Post subject: Reply with quote

adam2 wrote:
I have a nasty suspicion that fully repairable/rebuildable l.................

.....uprising current, and should be protected by a fuse.
Take great care in handling the acid.
Lead is fairly safe provided that you dont eat it.
Absolutely brilliant Adam. Thanks.

One thing I dont understand, how is the voltage determined for a given home-made cell?
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Tue Nov 13, 2012 4:01 pm    Post subject: Reply with quote

The voltage of any lead acid cell will be about 2 volts.
Varying the design and the surface area of the plates will alter the capacity and the robustness or otherwise of the cell, but not the voltage.

The voltage will vary slightly according to temperature and state of charge, but not by much.

Two small strips of lead in a lab beaker will have the same voltage as a cell weighing hundreds of kilos.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Tue Nov 13, 2012 4:19 pm    Post subject: Reply with quote

adam2 wrote:
The voltage of any lead acid cell will be about 2 volts.
Varying the design and the surface area of the plates will alter the capacity and the robustness or otherwise of the cell, but not the voltage.

The voltage will vary slightly according to temperature and state of charge, but not by much.

Two small strips of lead in a lab beaker will have the same voltage as a cell weighing hundreds of kilos.
Thanks Adam. That's really logically neat and makes it easy to scale up because you are only having to deal with the one variable of amps hours. Is it because of the particular properties of lead and acid in combination with one another? In other words, why not any other voltage?
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Tue Nov 13, 2012 5:28 pm    Post subject: Reply with quote

There must be some underlying reason in basic physics and chemistry, but for practical purposes it may be regarded as just one of those things, that a lead acid cell has a voltage of about 2 volts, just as a leclanche cell is about 1.5 volts, and a nickel iron cell about 1.2 volts.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Tue Nov 13, 2012 6:05 pm    Post subject: Reply with quote

adam2 wrote:
There must be some underlying reason in basic physics and chemistry, but for practical purposes it may be regarded as just one of those things, that a lead acid cell has a voltage of about 2 volts, just as a leclanche cell is about 1.5 volts, and a nickel iron cell about 1.2 volts.
Thanks Adam.

Is a nickel iron cell made in the same way as a lead acid one or are there some important differences in the construction?
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Tue Nov 13, 2012 9:15 pm    Post subject: Reply with quote

I found an instruction article that shows how to make a nickel iron cell from scratch.

There's a link here

http://nutsvolts.texterity.com/nutsvolts/201202?pg=38&search_term=edison%20battery#pg38

If you click the "print" button on the page, it saves as a pdf. Just make sure you only save from page 38 to page 43 otherwise you'll get a load of stuff you may not want.
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
kenneal - lagger
Site Admin


Joined: 20 Sep 2006
Posts: 9822
Location: Newbury, Berkshire

PostPosted: Wed Nov 14, 2012 2:46 am    Post subject: Reply with quote

I read two pages and then it asked for a subscription, Steve.
_________________
"When the last tree is cut down, and the last river has been poisoned, and the last fish has been caught, Only then will you find out that you cannot eat money". --The Cree Indians
Back to top
View user's profile Send private message Send e-mail Visit poster's website
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6220
Location: North Somerset

PostPosted: Wed Nov 14, 2012 9:48 am    Post subject: Reply with quote

The making of nickel iron cells is a little more involved than the very basic lead acid cell I described above.
The level of technology is broadly comparable to that required to make a modern lead acid cell.
Certainly within the capabilities of a local and relatively low technology works or factory in a post peak world.
Not really viable for most people at home though, unless they have invested a great deal of money and effort.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Wed Nov 14, 2012 11:03 am    Post subject: Reply with quote

kenneal - lagger wrote:
I read two pages and then it asked for a subscription, Steve.
If, when you get to the page, you go straight to the print button on the page and ask it to print from page 38 to 43, it will then save those pages to a pdf on your hard drive
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Wed Nov 14, 2012 11:06 am    Post subject: Reply with quote

adam2 wrote:
The making of nickel iron cells is a little more involved than the very basic lead acid cell I described above.
The level of technology is broadly comparable to that required to make a modern lead acid cell.
Certainly within the capabilities of a local and relatively low technology works or factory in a post peak world.
Not really viable for most people at home though, unless they have invested a great deal of money and effort.
Yep, from what I have read of the two types, lead acid seems easier. With the nickel iron ones, you've got to make an oxide paste and somehow get it to adhere to the nickel plates. The author of the article did it with conductive epoxy, but that is horrendously expensive and there is no way of knowing if that glue would hold up over a number of decades immersed in a highly caustic electrolyte, which is the primary point of having nickel iron batteries (for their supposed extended lifespan) in the first place.
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
Display posts from previous:   
Post new topic   Reply to topic    PowerSwitch Forum Index -> Electrical, Theory and Practice All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group