# A car battery submerged in water? **URL:** \ **Category:** Factual Questions\ **Created:** [January 12, 2008, 6:20pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308 "2008-01-12T18:20:11Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![happywaffle](https://avatars.discourse-cdn.com/v4/letter/h/ee59a6/32.png) [@happywaffle](https://boards.straightdope.com/u/happywaffle)\ **Post date:** [January 12, 2008, 6:20pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/1 "2008-01-12T18:20:11Z")
This morning, I noticed two things on the side of my house: (1) a trash barrel that’s always been there had lost its lid, and gradually filled with rainwater. (2) The home’s previous owner apparently left a car battery at the bottom of the barrel. So now I’ve got a submerged car battery. The question is, is there any possible problem with the rainwater? Should I hesitate before dumping it all out into the street or lawn? ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [January 12, 2008, 6:35pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/2 "2008-01-12T18:35:51Z")
There is a very high probability that the water is contaminated with sulphuric acid. Before discarding it it should be neutralised. I’d propose using Sodium Hydroxide (NaOH) but great care is needed in handling this material and even more so with adding it to an acid solution or even plain water. It may be advisable to contact your local public health department for advice on how to deal with it as special conditions apply in different communities, especially regarding the disposal of hazardous waste and materials and also batteries. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 12, 2008, 6:46pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/3 "2008-01-12T18:46:02Z")
Do not neutralize it with sodium hydroxide. Neutralize it with baking soda. If it doesn’t bubble, then you may be lucky. That is an indication that the battery didn’t leak. Double check with some pH paper though. (I’m not sure where to get that.) First, without touching anything and wearing gloves … I would get the battery out of their and into several garbage bags. Figure out where the proper place to dispose of the battery is. The water could be contaminated with lead. It may need to be treated as hazardous waste $$$. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 12, 2008, 6:50pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/4 "2008-01-12T18:50:10Z")
How contaminated the water is would depend on several factors. The design of the battery if a cap(s) were left off the battery The state of charge of the battery when it was submerged (the deader the battery the less H+ and SO4- ions are present in the solution) the amount of water in the trash can. If I had this problem, I would remove the battery from the trash can first. Then I would add some baking soda to the water to observe the reaction. If you know someone with a spa or pool, you can ask for a couple of PH test strips to get an idea of how acidic the water is. My personal wag is that the water is not terribly contaminated, and some baking soda will buffer it out just fine. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [January 12, 2008, 7:10pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/5 "2008-01-12T19:10:07Z")
[QUOTE=Rick] I would remove the battery from the trash can first. [/QUOTE] Even weak H[sub]2[/sub]SO[sub]4[/sub] excels at eating through cloth. The damage doesn’t show up until you wash your clothes. Then you’ll find your nice new jeans have a collection of pinpoint holes, where the acid hit. Add a teaspoon of baking soda to the barrel and observe what happens. If it doesn’t fizz much, dump the barrel and dispose of the battery. If it fizzes like crazy, the battery’s leaked. Add baking soda until it stops fizzing. It’ll take a _lot_. Let the barrel sit a few hours, then try adding some more baking soda. If it fizzes a lot, repeat. When it no longer fizzes, drain the barrel and dispose of the battery. -Plastic gloves are a good idea. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 12, 2008, 7:31pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/6 "2008-01-12T19:31:21Z")
[QUOTE=Squink] Even weak H[sub]2[/sub]SO[sub]4[/sub] excels at eating through cloth. The damage doesn’t show up until you wash your clothes. Then you’ll find your nice new jeans have a collection of pinpoint holes, where the acid hit. [/QUOTE] I agree. I just have one question. Why would I climb into the barrel feet first to remove the battery? I’m having a bit of a problem wrapping my head around just how you intend to remove the battery. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [January 12, 2008, 7:43pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/7 "2008-01-12T19:43:46Z")
Any way to drain the barrel into plastic containers? Reading **Rick** ’s post perhaps I overdramatised the situation here but do err on the safe side. A litmus paper test is indeed a very reasonable suggestion. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [January 12, 2008, 7:47pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/8 "2008-01-12T19:47:43Z")
[QUOTE=Rick] I agree. I just have one question. Why would I climb into the barrel feet first to remove the battery? I’m having a bit of a problem wrapping my head around just how you intend to remove the battery. [/QUOTE] -Scuba suit. Just wanted to point out that wearing your sunday best to take on this task would be stupid. With that volume of water, there _will_ be some splashing, and the consequences of that are not nil. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 12, 2008, 7:57pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/9 "2008-01-12T19:57:47Z")
[QUOTE=Squink] -Scuba suit. Just wanted to point out that wearing your sunday best to take on this task would be stupid. With that volume of water, there _will_ be some splashing, and the consequences of that are not nil. [/QUOTE] On that point we agree. However assuming that we are talking about a 33 gallon or so trash can and a small car battery which was fully dead when placed in the trash can, the acid concentration is going to be very low. I’m too lazy to do the computation, but a car battery takes a bit less than a quart of 64% H2SO4 (give or take depending on the size of the battery) And the concentration goes down as the battery goes dead. Depending on the design of the battery very little of the electrolyte may have gotten into the water. I still wouldn’t wear my best suit and tie to remove the battery. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [January 12, 2008, 8:15pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/10 "2008-01-12T20:15:50Z")
[QUOTE=Rick] a car battery takes a bit less than a quart of 64% H2SO4… [/QUOTE] Call it 12 molar. The 33 gallons of water will take that down to about 100 millimolar, which’ll give the mixture a pH of about 1. As you say, the battery may be dead, or the acid may not all have leaked, but from a safety standpoint, the worst case possibility is the one to look at. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 12, 2008, 10:01pm UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/11 "2008-01-12T22:01:34Z")
[QUOTE=Squink] Call it 12 molar. The 33 gallons of water will take that down to about 100 millimolar, which’ll give the mixture a pH of about 1. As you say, the battery may be dead, or the acid may not all have leaked, but from a safety standpoint, the worst case possibility is the one to look at. [/QUOTE] That assumes a full mixture of the acid with the water which I don’t believe is a given. Many batteries only have a single small vent which would inhibit the mixing to a great degree. However the longer you leave the battery in the water, the more of the acid will mix with the water. Also a dead battery is going to have a much lower concentration of H2SO4 than what the battery was filled with. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 13, 2008, 12:00am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/12 "2008-01-13T00:00:43Z")
[QUOTE=myglaren] Reading Rick’s post perhaps I overdramatised the situation here but do err on the safe side. [/QUOTE] You should never neutralize something with sodium hydroxide. With sodium hydroxide, the difference between neutral and basic is extremely small. Allways neutralize acid with a week base. If it is really acidic, you can use sodium carbonate. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [January 13, 2008, 1:12am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/13 "2008-01-13T01:12:19Z")
I’m going back some years now but I used Sulphuric Acid and Soduim Hydroxide to balance the pH of processing solutions in photochemistry so these were my natural choices. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 13, 2008, 1:37am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/14 "2008-01-13T01:37:03Z")
Understandable, but in that case you were working with well designed chemistry, and you either had very consistent solutions, monitored the neutralization closely, or the resulting pH was not important. When you are trying to get an unknown acidic solution to neutral for the purpose of making it safe, you always want to use a weak base. Sodium bicarbonate is the standard. Honestly, I’m not sure what you would use to neutralize a basic solution. I think most vinegar solutions are too weak to have much effect. Any ideas anyone? ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [January 13, 2008, 2:08am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/15 "2008-01-13T02:08:27Z")
[QUOTE=Squink] Call it 12 molar. The 33 gallons of water will take that down to about 100 millimolar, which’ll give the mixture a pH of about 1. [/QUOTE] Don’t you mean the pH would be closer to 7? ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 13, 2008, 2:22am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/16 "2008-01-13T02:22:51Z")
A 100 millimolar solution of sulfuric acid, the concentration of protons is 0.1 M. The pH is defined as the negative log base ten of the concentration of protons. That makes the pH of this solution 1, as **Squink** said. ---
**Author:** ![Rico](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rico/32/3582_2.png) [@Rico](https://boards.straightdope.com/u/Rico)\ **Post date:** [January 13, 2008, 3:00am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/17 "2008-01-13T03:00:13Z")
If you took an eydropper full of that solution and added it to another 33 gallon can full of water, then took an eyedropper full of _that_ solution and added it to another 33 gallon can full of water, does that mean you would have a homeopathic acid solution that would only _snack_ through cloth? ---
**Author:** ![WoodenTaco](https://avatars.discourse-cdn.com/v4/letter/w/45deac/32.png) [@WoodenTaco](https://boards.straightdope.com/u/WoodenTaco)\ **Post date:** [January 13, 2008, 4:07am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/18 "2008-01-13T04:07:05Z")
[QUOTE=Rico] If you took an eydropper full of that solution and added it to another 33 gallon can full of water, then took an eyedropper full of _that_ solution and added it to another 33 gallon can full of water, does that mean you would have a homeopathic acid solution that would only _snack_ through cloth? [/QUOTE] No, it would repair holes in clothing. Sheesh, so much ignorance to fight! ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 13, 2008, 4:11am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/19 "2008-01-13T04:11:42Z")
Take a quick look at Wiki it appears I was wrong about the acid concentration in a lead acid [battery](http://en.wikipedia.org/wiki/Lead-acid_battery). The article on lead acid batteries says about 37% and the article on [Sulfuric acid](http://en.wikipedia.org/wiki/H2SO4) says about 33%. So it appears I was got the percentage of water and acid bass ackward in my mind when I wrote my post. However I did see this in the battery article > [@](#): > > Each cell contains (in the charged state) electrodes of lead metal (Pb) and lead (IV) oxide (PbO2) in an electrolyte of about 37% w/w (5.99 Molar) sulfuric acid (H2SO4). In the discharged state both electrodes turn into lead(II) sulfate (PbSO4) and the electrolyte loses its dissolved sulfuric acid and becomes primarily water. Which reinforces what I have been saying, if the battery was dead when placed in the trash can, there will be little acid left anyway. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [January 13, 2008, 4:19am UTC](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308/20 "2008-01-13T04:19:04Z")
Sure. That’s about a 60,000 fold dilution each time, so it’d take the acid concentration down by a factor of 3.6 billion. The pH would then be governed by how much atmospheric CO[sub]2[/sub] had been absorbed by the water. On a practical note, it’d take 118 billion gallons of water (0.45 cubic kilometers) to dilute the entire barrel by that factor. [Next page](https://boards.straightdope.com/t/a-car-battery-submerged-in-water/433308.md?page=2)