Specific gravity

[TheCasualTraveler]

What should be the specific gravity of electrolyte before putting it into a battery.

     I have a 12 volt deep cycle battery that sank with a boat. I am trying to revive it by washing it out, adding EDTA and new electrolyte. I got the acid from the local auto parts store and they said to add it straight as it is, evenly to all cells till either the cells are full or the acid container is empty which in the second case you fill the rest of the way with distilled water. I don't like to take  stuff like this for granted and also am curious to know what concentration of acid was still in the battery IF ANY. So, my question again,

     What should the specific gravity of electrolyte before it is put into the battery? Also, if you pour out the electrolyte from a battery and test it, what should the specific gravity of electrolyte be?

ps, yes I'm using safety glasses etc.

[Flux]

Not sure what luck you will have. Much depends on how long it was submerged and how much salt water displaced the electrolyte.

Normally the acid sg would need to suit the state of charge of the battery at the time.

If it was reasonably charged then adding acid with sg of about 1.25 would be reasonable. If it was in a low state of charge you would need something lower perhaps 1.10 so that it came up on charging.

In your case I suspect the chap at the auto store may be right as long as he is giving you normal diluted acid. I very much doubt that he would be in a position to offer you Pure concentrated acid.

I suspect in your case it is  just a last ditch chance and there may not be too much point in being scientific. If it looks to be working you can adjust the sg after full charge by removing some electrolyte and adding water or more acid to get a reasonable sg. If you have got much salt water in there I think they are a gonner.

Flux

[bob g]

for what it is worth

without knowing the state of charge when it sank i would do the following

1. drain all the old electrolyte, and fill the cells with fresh distilled water, and measure and log the specific gravity of each cell
   
2. put it on a charger and monitor the specific gravity of the water in each cell
   
   

and log the results

3. continue for maybe 24 hours or until the specific gravity has risen and stabilized at its peak reading on each cell,, check your log

*not knowing the history of the battery, how old it is, what its state of charge was

etc.. i might leave it on the charger for several days at an equalization voltage

with the distilled water. you want to be sure all or most all of the sulfation has been broken down and the acid contained is returned to the water, which will be indicated by a rise in specific gravity in the water.

it goes without saying to keep the temperature within reason as well,, if it gets hot let it cool off and then start charging again.

what this accomplishes is breaking down the sulfate which hopefully has not crystallized

now if the battery is any good you can drain the battery and refill with fresh electolyte, filling them to the top of the slots

do not add water if you run short of electrolyte, get more!

if you add water you will only reduce the specific gravity of the electolyte.

put it back on the charger for a few hours and test the results

if the battery was an old one that was near its useful life, it probably won't be worth the effort, if however it was fairly new and had been maintained properly it might be worth the effort.

forget the edta!

bob g

[TheCasualTraveler]

Thanks for the advice, a couple more questions...

Bob, why did you say forget the edta? I have several deep cycle batteries I am trying to revive. One of them shows completely discharged by SG. I had it on a charger for 2 days without any improvement. I added a little edta in each cell and it is starting to come up after 1 hour.

Also, I'm still curious, what should be the SG of the acid before I put it in the battery? Would it even show on the tester?

[jimjjnn]

BEWARE !! Battery acid and saltwater form a deadly gas when mixed. A lot of WWII submariners died from the gas when saltwater got into the battery compartments.

I would rinse the battery out several times with distilled water and then try recharging as others have said here.

[wpowokal]

Andy read the post by Flux, I believe he answered that.

allan

[TheCasualTraveler]

Well, I re-read Flux's post three times and I guess I just don't understand. Tomorrow I will open the new package of electrolyte, suck some up in my tester straight before putting it in the battery and then I will know if it's SG can be measured and if so, what it is.

[TomW]

bob;

I never tried EDTA. Never will. I figure it is like that "tune up in a can" stuff for cars. If there are physical problems pouring "stuff" in is not going to help. Most of the proponents of EDTA seem to be the ones hawking it for sale.

Just an opinion with no experience.

Cheers.

TomW

[Ponderance]

Just curiosity here:

Considering the grade-school science experiment from my younger days (about 20yrs ago) salt water conducts electricity fairly easily.  My concern would be if you shorted out enough to burn up plates (state of charge being concern here) if it was submersed any length of time with a 30% or greater charge would make me wonder if the plates are still good.

[bob g]

Andy:

pure water has a specific gravity of 1.000

fresh electrolyte is somewhere around 1.250-1.260 if i recall

i will continue to rail against edta and desulfators in particular

until i see someone like sandia labs running true double blind tests showing

that this stuff works reliably and why.

if anyone has a link or reference to this sort of testing by an indepedent lab

i would like to see it.

until then i look at this stuff as i do fuel line magnets

as suggested flush that battery out very well, you don't want to get injured with poisonous gases.

usually heavily sulfated batteries are very hard to get to take a charge because most chargers are incapable of getting sufficient voltage to break down the crystallized sulfation.

i am not saying that edta or desulfators don't work at all, i just don't think they work reliably enough to support the claims that the folks that sell the stuff put out.

however... if i had a battery of known quality (not worn out) that was allowed to get heavily sulfated and i could not recover it by conventional means, then i might resort as a last ditch effort to the use of other means. but only as a last resort

and never as an addition to a good battery.

bob g

[bob golding]

chlorine i presume???

[Ponderance]

The by-products of mixing sulfuric acid and sodium chloride (salt and wet-cell lead-acid battery)

http://en.wikipedia.org/wiki/Sodium_sulfate

http://en.wikipedia.org/wiki/Hydrogen_chloride

Hydrogen chloride forms corrosive hydrochloric acid on contact with water found in body tissue. Inhalation of the fumes can cause coughing, choking, inflammation of the nose, throat, and upper respiratory tract, and in severe cases, pulmonary edema, circulatory system failure, and death. Skin contact can cause redness, pain, and severe skin burns. Hydrogen chloride may cause severe burns to the eye and permanent eye damage.

[TheCasualTraveler]

Let me explain my situation a little more...

     I live across the street from a marina and marine repair shop. Every week or so there is a pile of used deep cycle batteries, practically on my doorstep, that the shop throws out. This is just too tempting for me not to try experimenting on. The key to me having a viable alt energy source is to get 1 or more parts of the system for a very low cost. Since wind here is good enough to supply a little power but not a lot, and solar panels aren't free I'm looking to these bats to make my system cost effective. My supply is unlimited and free so I am willing to try anything including any tests anyone else might ask me to perform. At the very least I can take the best of these bats and have at least limited storage, since many of them hold quite a bit of power, but not enough to rely on in a boat. The rest will bring a few bucks at the recycle place. One of them was the one that sunk. I chose that one to fill with edta and water after draining the diluted electrolyte and THOROUGHLY rinsing out the bat with fresh water.

     Thank you Bob G for this,

"pure water has a specific gravity of 1.000

fresh electrolyte is somewhere around 1.250-1.260 "

a simple piece of common info yet somewhat elusive. Very valuable to me in learning what I'm doing here. I am also rigging a set of heavy jumpers coming from my trucks battery so I can hook up these test bats in parallel and give them a good charge while I drive. Eventually I will build some sort of charger for equalization. In the meantime I value this forum's help and hope I can give help and info in return.

[Flux]

If you have the option of so many batteries then I would not waste time on any that have had significant quantities of salt water in them.

As for the rest, you will occasionally drop lucky and manage to salvage some that may be good enough for your modest needs.

Batteries die for many reasons, those that have had serious use will be worn out and most of the plate material will be in the bottom of the case, nothing will fix them.

Others will have been over charged and the positive link bars will be heavily corroded and will fail. These will show high sg but will not deliver large currents and may still run small loads. Those used for starter duty may fail to start an engine but may supply lights.

Occasionally you get one that is heavily suplhated and will not take a charge, its sg will be near water and you may be unable to read it. This may be the best candidate for edta if you can get it cheap ( I can't, costs more than its worth). It clears surface sulphate and lets you start charging. If it has been sulphated for long then it will never become a good battery but you seem prepared to accept that.

I have no belief that any pulse desulphator does actually do any desulphating. If they worked the sg would rise but it doesn't. There is no battery resonance that they are claimed to work on, that resonance is circuit resonance and you can calculate the ring frequency from the length of the battery.#

Yes I know some will claim to salvage batteries by this means but I don't think the ones that respond are sulphated, they have other defects and stinging them with high current pulses does something to improve plate conductivity. There may be some benefit in using these things on good batteries, it may have some of the beneficial effects of equalising and may delay normal soft sulphate from going crystalline.

Most sick batteries respond to a good equalising and some of the things attributed to these pulse circuits often come from the prolonged low level charging that comes with the process.

Basically scrap batteries never become good ones, sometimes they become usable if your requirements are modest. Fine if you have the time to waste and you will soon learn which ones respond and which will never be any use.

Fortunately many good batteries are scrapped when really there is not a lot wrong with them but "user trouble" they are the ones to look for.

Flux

[DanG]

Make sure there is a fuse link on any new cable you add - a high current DC circuit breaker as on/off switch is good since just it would be as soon as you are confident w/ your mods then driving amongst the orange glow of cables melting blinded by smoke from under the dash board etc. makes a believer out of you... "Murphy's Law" wants you!

[TheCasualTraveler]

Advice taken. I put the cables in this morn as a matter of fact and was going over it, making notes of safety precautions such as protection everywhere the cables can rub anything. A breaker sounds like a dern good idea. I've seen red hot battery cables. That said it sure seems like the easiest way to put a lot of juice into an old battery, and they really seem to take notice, even the one that sank on the boat is doing fine. If I take one battery at a time out of my bank and charge it, return it and take the next, is that an equalization charge or must that be done to the bank as a whole.