Nope.

It's stronger than that.  I guessed at around 40% when I first read your post, but a quick look-up gives it around 30%.

As a chemistry technician I once made-up some from conc. sulphuric, it hissed and spat and got quite warm, and I was glad when I'd finished!

SpinningMagnets:

 I can assure you that im no novice when it comes to handling chemicals. Now, what your describing sounds much more like nitric acid ACS, or chromic-sulfuric acid. Ive gotten sulfuric acid (acs) on my bare hands before, its not really a big deal, phosphoric acid is even less of a worry to me. Actually HCI has very toxic vapor's when combined with water. So dont inhale them.  :)

Thanks Mark,

 I was more concerned about possible re-active lead content. I know that dilution before dumping helps alot. Could go a long way to lock things up.

As I mentioned, forming a black dirt/sludge in the bottom of such a solution, that could be mechanically filtered out, would make me feel better. Since I dont want there to 'even' be a chance that a lead-sulfied or whatever else, getting into the watershed.

Rural McG,

I think yours(comment) is the best with regards to getting rid of used electrolite. Id like to be able to 'flush' the electrolite in my batterys. Im only working with 2 batterys and they are a top of the line type. So the matting inbetween the plates is in exceptional condition. These batt's are about 5 years old, seem's to me I paid over $250 for each. If I can rebuild them, Id like to. The big prolem was what to do about any spent or flushing electrolite. Containment is not a problem at all, I have a nice polyurethane high wall tray to spill the batterys into. Just didnt know what to do with the stuff after flushing the batts. Thanks Rural..

OK,

 Now ive started the process, and am not going to have any waste for this first phase. I have found 5 of the 6 cells in each batt were low. I have just added distilled water to them. So far the specific gravity meter will not even register low charge.

Rather than rush into adding 1ml of phosphoric acid to each full cell. I will add some sulfuric acid and try to get the SG meter to register on its lowest point of its scale.

I use pipettes to add acid(acs) to the battery. I will only use the phos acid if the battery does not respond to a more conventional treatment.

 So after I reach the SG with the sulfuric, I will set the batts off to charge with a wall transformer, then check the SG after that. If things go well, I wont mess with the phos acid additive, also im 'not' using ETDA additive.

 At this point the only thing that I plan to add is ACS sulfuric in very small quantitys such as 1 or 2 ml. But this will occur before any charging. I plan on letting the batts sit for a day or so after adding anything, then charge.

 I checked the specific gravity of the cells in this battery today, all cells are now in the silver or 'fair' range. Although they are at the bottom of the this range, the readings are significantly improved. In this battery there were 5 boiled out cells. The one cell that was in the fair range yesterday, is now in the bottom of the blue range or 'good' according to the scale on the SG meter. Charge time has increased correspondingly.

 After the readings yesterday I added 4ml sulfuric, then discharged/re-charged, to get my SG readings today. Today, I again added, 4ml sulfuric to the the cells, bringing the total added to 13ml for 5 of the cells and 9ml total to the one cell that came around first.

 The other battery has only had a total of 3ml added to each cell, Ive not measured the SG of its cells yet. But its charge rate is normal. This means that it takes a full 48 hours to recharge from discharging to 11.75 volts. In this amount of time the voltage never exceeded 13.75 volts.

 Im not quite sure, if the difference between the two, is the condition of the plates or whatever. But the weaker of the two, is gaining capacity, as a result of adding the sulfuric. I kind of do things one step at a time, if it needs it, kind of thing. Since the performance of the one, is at what I consider good, I dont just arbitrarily add additional sulfuric. I wait and see how things are going, then make a decision based on that. This is why I never added anything but distilled water and sulfuric (acs) to these batts.

 Also it has been advantageous to restore the original electrolite. I see no problem matching the capacity of both batterys, and getting SG readings in the blue or 'good' range, using this method.

 Im going to use the batts tomorrow night, to power the 115 watt lighting system on my boat, for sighting some lobster on the flats. I will use the system for about 6 hours as we will use them for some night fishing too.(hopefully the water will be calm) Lobster season opens in august. I do have an 6amp charging alt, on the motor to keep things going. Before I boiled these out, 6 hours run time, was no problem for these batts in parralel with the engine not running.

 Before I was thinking, of trashing these batterys, but it would cost $500.00 to replace them, so im very pleased with all this progress. They have a production date of 08/2002. More SG readings to come next week. At that point I will be about done with this process and batts should be in good shape again.  :)

 Here's a picture of the caps on this battery, they do seem to have a type of valve built into them, then some type of diffusion membrane, on the other side of it.

Anyhow, the batt that I discharged down to 5.55v has been charging over 17hours, @400ma at 12 volts, is doing quite well. If the thing takes a charge for 48 hours, like it might, the capacity should be good. Trust me Im surprised...