Sciencemadness Discussion Board

large battery, ideas?

Panache - 8-3-2010 at 09:07

A friend recently had to move factories and as a final clearout had an auction which was well cleared however i missed it. Visiting him two days before he was finally vacating i perused the remaining stuff that hadn't sold and to my delight it was all kinda interesting, i took several things, one of which i now kind of regret but oh well. It is a very large battery, some 750mm wide, 500mm high and 100mm deep. It is encased in a thin steel box.
If i attempt to lift one side of it via the jerk strap i cannot even shit it one mm, i may as well be trying to lift a house, so from this i assume it weighs around >250kg, the forklift (of my neighbour) strained somewhat lifting it off the back of my ute.
I assume its a lead acid battery, there are numerous cells across the length attached one to another.
I get a 5amp reading on my multimeter across the terminals.

So any ideas on what it may be and what to do with it. I could put it on castors and use it as a portable 12V DC power supply, hmmm.
i guesss i should take a photo. back soon.

Image004#2.jpg - 38kB

[Edited on 8-3-2010 by Panache]

Nicodem - 8-3-2010 at 09:24

Looks like the battery for an electric "walkie-forklift". Its origins also hint toward this. Given it was taken out it could be because it was replaced due to bad performance.



You could make a short range electric car with it. :P

aonomus - 8-3-2010 at 09:38

Chances are its a big hunk of hazardous waste disposal costs that someone decided not to pay, and just keep it around.

That pack is almost certainly either a forklift pack as mentioned above, or a telco backup battery (but these are in the 48V range). If you read its current output on a 10 amp multimeter setting, it should have destroyed your multimeter. These things should easily put out 50-100A at 12VDC, having said that, its probably past its service life, very old, and sulfated. There *are* ways of desulfating plates mechanically and with copious amounts of EDTA, but really unless you are desperate and wanting exposure to lead compounds, its not worth it.

If it worked however, it might have been.

12AX7 - 8-3-2010 at 10:59

Looks to be 12 cells, or 24V, ~28V nominal.

If you're lucky, you can add some distilled water to the filler caps and baby a charge back into it (low current (couple amps?), at whatever voltage it takes (could be quite high), for as long as it takes to get voltage back down to nominal).

If nothing else, you can smash it up and recover a fair bit of lead.

Tim

chief - 8-3-2010 at 12:26

Lead is worth more than 1000 $ per ton, if quantity permits a good selling; only for batteries they like to not pay, but take them at best for free (making the bucks themselves) ...

At 24 V the thing would easily give a kilo-Ampere or more, depending on the resistivity of the circuuit ... which would have to be in the milli-Ohm range for that ...

So if it doesn't work maybe it can be sold ...; finally lead is worth more than nothing ... (except in the EU, where almost any valuable scrap is declared a "hazard", so that the people have to give it away for free ...)

Contrabasso - 13-3-2010 at 17:20

Check the cell levels then check whether it holds charge. It looks like a fork truck power pack, and if it works would make a good store for a wind/solar eco power system.

Panache - 16-3-2010 at 16:59

Quote: Originally posted by Contrabasso  
Check the cell levels then check whether it holds charge. It looks like a fork truck power pack, and if it works would make a good store for a wind/solar eco power system.


Is assume the cell levels are checked simply by opening them and ascertaining the amount of fluid in them and then filling them to some undefined point?

How do you check whether it holds charge? (i'm sorry and yes these questions seem idiotic, but if i'm not spoon fed it will sit in my shed for several decades)

Contrabasso - 17-3-2010 at 11:19

Wear protective clothing and clean the cell tops. then see if the fill covers come off. If so open up and add purified water (Distilled or de-ionised) to the cells to bring the level up to the top of the plates.

Charge the battery for a long time using a charger of sufficient voltage to drive say 10 - 20 amps in. Drive in say 20 - 50 amp hours then try to get some current out -say some car bulbs to match the volts. If you get out some fair amount of the power that you put in then the battery is serviceable. If not then you have to find the fault or scrap it properly.

You really should look for some indication numbers on the batteries and search them on the www to find the properties of the cells and the assembled battery.

bdgackle - 29-3-2010 at 02:07

Warning on reclaiming the lead -- batteries frequently contain other metals added to increase the strength of the plates. On melting down, it's possible to end up with stibine / arsine gas.

I melt down lots of scrap lead to cast bullets, so I'm not exactly lead-phobic. Even among bullet casters, though, battery salvaging is generally avoided -- and we're all pretty desperate to stockpile lead these days.

Since this is a Chemistry forum, and not a bullet casting forum, I'd be interested in hearing from anyone that thinks the above warning is invalid -- maybe its more of an urban myth passed around among us rednecks.

hissingnoise - 29-3-2010 at 03:23

Whatever about arsenic, we know antimony is used in battery plates and ball-milling media but stibine, smelling like H2S, oxidises fairly quickly in air.
It is though, very toxic and its possible formation should be taken into consideration when melting battery Pb.
Antimony-hardened leads includes fishing weights, wheel weights and any lead articles that do not deform easily. . .



[Edited on 29-3-2010 by hissingnoise]

not_important - 29-3-2010 at 04:47

Both SbH3 and AsH3 decompose to the elements at temperatures below the melting point of lead. To make them you need both fairly strongly reducing conditions and a hydrogen source.

I'd worry more about the corresponding oxides coming off the melt. Both PbSO4 and PbO2 will function as oxidising agent at those temperatures, I don't see the hydrides having much of a chance but the oxides could easily be formed.

If I were reclaiming lead from old batteries I'd first well wash the lead, let it dry, melt up some previously reclaimed lead and cover it with an alkaline flux like borax+soda ash, meaning temperatures in the range of 700-800 C. I'd then add bits of old battery plates while blowing a stream of air through the pot. Under those conditions most of the alloying metals should oxidise and end up captured by the flux. When all the lead is in and has been stirred for awhile, skim off the flux and add fresh flux, repeat once or twice to get any nasties away out of the pot. After that drop the temperature and do any usual reducing fluxing you do, then cast the lead. The used borate flux should be considered toxic, and kept away from acids unless remelted with additions of Na/KNO3 to oxidise any metal trapped within the flux; it then could be worked up for Sb/As recovery.


[Edited on 29-3-2010 by not_important]

bquirky - 29-3-2010 at 05:20

I wonder if There might Be some elegant way To acid Leach The oxides and Sulfides out of the cell prior To smelting and prehaps Then plate out The lead from The liquor


or Just plate The lead straight out of the cell and Leave the insolubles behind in the battery case

Skyjumper - 29-3-2010 at 15:51

short it out. Make big boom

not_important - 29-3-2010 at 17:06

Sulfides? In a lead-acid battery?

You can convert the lead sulfate to lead carbonate by treating with warm aqueous Na2CO3. On smelting the carbonate decomposes to PbO, the PbO2 decomposes to the same while oxidising more reactive metals in the mix. You can either add reducing fluxes, including organics such as sawdust, to reduce the lead oxide, then follow with the high temperature alkaline flux oxidation to pull out the other metals; or you can just use the allow as-is if it has the needed physical properties.

Electroplating or electrowinning of lead is usually done with fluoroborate electrolytes, perhaps less than convenient. Try to do that with the more or less intact battery is likely to be a large bother.


See United States Patent 4769116



[Edited on 30-3-2010 by not_important]

Sedit - 29-3-2010 at 17:45

Batteries get aound 10cents a pound at junk yards honestly given the size of the thing I say sell it and buy yourself some new glassware or chems to play with.

Twospoons - 29-3-2010 at 18:03

Quote: Originally posted by Panache  


I get a 5amp reading on my multimeter across the terminals.

[Edited on 8-3-2010 by Panache]


You what?! Connected an ammeter across a Pb battery?! Just as well its completely stuffed or you wouldn't own an ammeter anymore.

Panache - 30-3-2010 at 17:43

thanks all for the replies couple of questions

Conrabasso-Is running a dc voltage equal to that of the battery with the poles reversed the same thing as what a charger would accomplish? When i connect a 12v globe am i expecting it to blow if the amps are too high?

NI-When you say 'wash the electrodes first' do you mean just with some warm water. Also when you say 'blowing a stream of air through the melt' do you mean violently or just a nice gurgle maintained over say 30mins?
If i do this in my kiln any idea on what ambient temperature i would set to achieve the 700-800C, i don't suppose i could use a stainless pot, (its 316 and 5mm throughout, however the bottom and one seam are tigged) as it fits snuggly in the kiln.
Does Pb contract sufficiently to simply allow it to cool in the pot and then i could remove it as i have no way of pouring ingots.
By skimming do you mean like skimming stock as in using a flat broad spoon type thing and grabbing the crap off the top?

Twospoons-How would you assess the possible amperage of a battery then?

Twospoons - 30-3-2010 at 20:22

Use a big dummy load that you can adjust - e.g. toaster element in oil, or similar, or a bunch of light bulbs. Your basic ammeter presents essentially a short circuit. Some battery chemistries (notably lithium) do not like being shorted and object strongly.
Your average meter will also object strongly when it gets 1000A shoved through it. The 10A range on a lot of meters is unfused (not smart, but thats the way it is).

[Edited on 31-3-2010 by Twospoons]

not_important - 30-3-2010 at 23:37

Quote:
Is running a dc voltage equal to that of the battery with the poles reversed the same thing as what a charger would accomplish?

Almost, chargers current limit to prevent damaging the battery. They also go above 12 V, as the open circuit voltage of a charged battery is around 14 V.

Quote:
When i connect a 12v globe am i expecting it to blow if the amps are too high?

How many amps comes out depends on the load resistance, and the voltage-current curve of the battery.

If the battery can deliver more amperage, at the design voltage of the bulb, than the bulb needs then only as much current will flow as the bulb is intended to draw : 24 W @ 12 V bulb draws 2 amps so long as the battery can deliver that. A low current battery will not produce enough current, it's output voltage drops if you attempt to pull more current than it can provide.
Quote:
NI-When you say 'wash the electrodes first' do you mean just with some warm water. Also when you say 'blowing a stream of air through the melt' do you mean violently or just a nice gurgle maintained over say 30mins?


Yes, just a water wash or two, water soak, or some combination to get the sulfuric acid out of the plates and separators.

Just bubble, keeping the metal mixed and supplying O2 to oxidise the more reactive alloying metals
Quote:
If i do this in my kiln any idea on what ambient temperature i would set to achieve the 700-800C, i don't suppose i could use a stainless pot, (its 316 and 5mm throughout, however the bottom and one seam are tigged) as it fits snuggly in the kiln.

No idea, too many variables to give a meaningful answer. You need to keep the alkaline flux liquid.

Quote:
Does Pb contract sufficiently to simply allow it to cool in the pot and then i could remove it as i have no way of pouring ingots.

Remember that after removing the alkaline flux and 'washing' with some fresh flux, you'll want to drop the temperature and add a reducing flux as per ordinary lead casting.

A pan of dry sand with trenches scraped in it works. I've used heavy sheet muffin pans. Wooden molds work if too much lead isn't poured in them.
Quote:
By skimming do you mean like skimming stock as in using a flat broad spoon type thing and grabbing the crap off the top?

Yes, you can make a skimmer out of scrap sheet steel.
Quote:
Twospoons-How would you assess the possible amperage of a battery then?[rquote]
As he said. An ideal amp meter has zero resistance, putting across a battery's terminal would result in the maximum amount of current the battery could deliver, and would damage the battery. Real world amp meters have a small but non-zero resistance, a precision low ohm shunt - the ampmeter actually measures the voltage across the shunt. (some amp meters measure the magnetic flux generated by the current flowing in the external wire, you don't directly connect them to the battery)

You will need to create a graph of battery voltage vs current being drawn to get an idea of its maximum current capacity. This means you need to be able to adjust the load resistance, even if only crudely.