Comments on: It's Alive!!!!

Question: It's Alive!!!!

scose — Mon, 23 Feb 2009 15:47:09 -0800

I have sulfuric acid, de-ionized water, and basic lab equipment. Can I revive my crappy car battery?

My battery holds very little charge. A couple of days ago, I left the radio on in my driveway for about one minute and the car wouldn't start when I got back. If I let it sit for more than a few days, it's iffy whether it will start.

Is there anything I can do, like drain out all the fluids and put in a new sulfuric acid solution? Or should I just purchase a new battery?

Also, don't worry about giving me safety advice. I know how scary H2SO4 is, but I'm a broke student and could do without spending ~$100 on a battery!

By: zippy

zippy — Mon, 23 Feb 2009 15:56:02 -0800

My understanding of battery failure is that when a battery is fully drained of charge, it's the battery plates that physically degrade. Clean water and fresh acid will not help with that.

That said, all I know about lead-acid batteries I read on random web pages, and I do know that the plates are made of sturdier stuff in some models (glass mat in some, cardboard!?! in others).

By: 517

517 — Mon, 23 Feb 2009 16:03:26 -0800

I'd pay $100 to avoid the possibility of chemical burns, lead poisoning, and a crappy battery that I will have to replace in a month anyway.

And what zippy said about the degradation of the lead plates.

By: pdb

pdb — Mon, 23 Feb 2009 16:04:25 -0800

If you're a broke student, can you afford the medical bills that might result from cracking open and monkeying with a car battery full of hazardous chemicals?

Purchase a new battery.

By: jquinby

jquinby — Mon, 23 Feb 2009 16:07:25 -0800

FWIW, I just replaced a battery at Autozone and paid about $70 after the core allowance.

Car batteries, as said, don't take deep discharging very well. This I've learned after replacing several batteries in the past, thanks in no small part to children who enjoy Climbing Into Things almost as much as they enjoy Pushing All The Buttons.

By: Cool Papa Bell

Cool Papa Bell — Mon, 23 Feb 2009 16:07:59 -0800

I'd be worried about doing this too well and a) creating a battery with a higher voltage output that harms some other part of your car, b) creating a battery that explodes and/or leaks acid or c) both.

Sometimes batteries just take a dump on you. I'd just replace it, and/or turn it into a real science experiment, and take it out of the car, hook it up to a volt meter, etc, etc.

By: 517

517 — Mon, 23 Feb 2009 16:13:57 -0800

Yup, it won't work. The plates will be saturated with PbSO₄, which would be stupid to try to clean off.

By: scose

scose — Mon, 23 Feb 2009 16:13:59 -0800

OK, you are all probably right... I guess I was hoping there was some secret revival technique that the battery manufacturers don't want us to know about, but it looks like battery death is more or less final.

By: Green Eyed Monster

Green Eyed Monster — Mon, 23 Feb 2009 16:20:23 -0800

Yep, it's the plates that are the problem, most likely.

By: Pinback

Pinback — Mon, 23 Feb 2009 17:36:05 -0800

Depends. As mentioned above, the plates in deep-cycle batteries tend to become sulphated*, leading to reduced capacity - and more so in car batteries, where the plates are not pure lead, but usually lead alloyed with antimony or similar to provide strength.

Most car batteries, though, tend to fail physically - the plates crack, break away from the grouping bar, get shorted by loose residue, etc. If they fail because of an internal (partial) short circuit due to residue build-up it is possible to wash them out and re-fill them, but usually not worth the effort (because that residue is material that has been lost from the plates anyway).

(* FWIW, it can in certain cases - large (1000's of A/H capacity) backup supplies in telco applications where the cost of replacement is high being one - be worth going to the trouble of 'de-sulphating' cells / batteries. But it's usually only a short-term measure, and you almost never get back full capacity.)

By: gjc

gjc — Mon, 23 Feb 2009 17:51:46 -0800

Pinback is correct. The basic answer is no. The acid bath isn't what fails, it's the lead plates.

More specifically, the lead plates are more like thin lead sheets, since the more surface area there is on the lead, the more amps the thing can put out. So the lead is very thin. In addition to that, there are other things that happen besides just acid and water.

Adding onto that, as the lead and acid interact over time, the lead doesn't reform exactly in the same malleable structure it started out as. It gets brittle and the failures mentioned occur.

By: notsnot

notsnot — Mon, 23 Feb 2009 19:39:47 -0800

For one, you don't have to worry about making "too much voltage"...the reaction has a specific voltage, times six cells.

But yeah, get a freakin' battery. The plates are toast. It happens more in winter, where there's more drain on the battery to turn over an engin full of more viscous oil, then you leave teh blower on...*cough*...anyway, once a dead battery is good and frozen - even a newish battery that just has been drained - it's good and dead.

By: Cool Papa Bell

Cool Papa Bell — Mon, 23 Feb 2009 20:18:29 -0800

For one, you don't have to worry about making "too much voltage"...the reaction has a specific voltage, times six cells.

What happens with a different acid solution? Wouldn't a lower ph solution than the standard create more electrons with a shorter overall battery lifespan?

By: Chuckles

Chuckles — Mon, 23 Feb 2009 20:59:51 -0800

Wouldn't a lower ph solution than the standard create more electrons

More electrons means more current, basically. I suppose it might reduce the internal resistance, which would have the effect of a slightly higher voltage in practice, but that isn't what you are talking about. Check out the wiki.

Of course I don't know much of anything about electrochemistry, so I might be missing something.

By: hattifattener

hattifattener — Mon, 23 Feb 2009 22:35:54 -0800

Reports vary on whether trying to desulphate a sulphated battery is at all worthwhile or not. There are various circuits you can find on the net (e.g.) which claim to be able to restore some capacity to a sulphated battery.

Sulphation is a different failure mechanism from having the plates physically degrade, though. Not much you can do if your plates are falling apart. I've heard that sometimes a battery will fail because, as the plates degrade, sludge builds up at the bottom of the battery and shorts out a cell or two; removing this sludge could possibly restore the battery. I think that's a pretty long shot though and how you would physically do that on a modern battery I don't know.

You could perhaps just trickle-charge the battery so it's not as much of an issue that it doesn't hold a charge very well.

In any event, you should plan to get a new battery when you can afford it, even if you manage eke out a few more months of use from this one.

By: Slinga

Slinga — Tue, 24 Feb 2009 06:55:20 -0800

Well, assuming you're going to stick with using this one until you either can afford a replacement or you figure out how to fix it, I would recommend:

Not using the radio (or at least not using it when the engine isn't running)
Turning off the overhead light so you can't accidentally leave it on
Starting your car every day whether you use it or not

That will at least help keep it from dying on you again. Best of luck!

By: yohko

yohko — Tue, 24 Feb 2009 21:30:49 -0800

If you look around there is probably an auto shop that sells used batteries. It won´t be in a nice neighborhood. The battery you buy there won´t be very good, but it will be cheap. Make sure it´s held down properly in the car, as it might be the wrong size.

By: zippy

zippy — Wed, 25 Feb 2009 01:01:08 -0800

Following up on yohko, you can buy batteries at Pick-n-pull. They're right by the entrance. PnP's exchage policy is generous - if it covers batteries then you're all set (assuming their prices are reasonable - call ahead).

By: scose

scose — Fri, 06 Mar 2009 00:45:29 -0800

Well, just to follow up, the water level in the battery was very low. I filled it up and so far, no jump starts needed. Looks like I've got a little bit more life out of it at least. Also looked up some plans for DIY trickle chargers, and it seems pretty easy to make one from a 12 volt wall wart and a big ol' resistor...