I work for an industrial company and I just returned from a two hour lunch and learn sponsored by the world's largest maker of industrial batteries. The seminar was conducted by an engineer with 30 years of design experience. I asked two questions that apply to the batteries I use in my car and boats. The answers dispel any old wives tales, urban legends, or misinformation.

1) Q: Is there anything wrong with adding tap water to a battery?

A: Yes! Tap water may contain impurities that basically alter the battery chemistry and can ruin the battery. He mentioned iron and copper as two elements found in low concentrations in tap water. There is not enough to hurt humans, but it can ruin a battery. Well water is to be avoided because it commonly has high iron content. Use only distilled or de-ionized water in batteries.

2) Q: Is there anything wrong with storing or charging a battery that rests on concrete?

A: No. Modern batteries with plastic cases will not experience current draw into concrete. However, batteries are very heavy and we have a tendency to slide them around on the floor instead of picking them up. Even smooth concrete is very abrasive and can damage the plastic case through friction.

Side notes: Interstate Batteries does not manufacture any of their own batteries. His company makes Interstate's high end models under a private label contract. A cheap battery does not last as long as a more expensive model because the plates are thinner and the acid solution is weaker. Hopefully, you get what you pay for.

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Behind every great man is a great woman. Behind every great woman is a great behind.

Distilled water is $0.99 for a gallon at our local grocery store. Why wouldn't you use it?

Because I haven't made a point of keeping some on hand for batteries. I will now.

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Behind every great man is a great woman. Behind every great woman is a great behind.

I always thought it was common knowledge that you use distilled instead of tap water to top up low cells? Even my mother knows that and she isn't too bright when it comes to technical things.

Charging or resting a battery on concrete can only discharge the battery if the case is very dirty and the concrete is damp. The filth layer can create enough of a parasitic drag to drain the battery - though it takes a LONG time (months) to do so.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

There is a bit more to this.

oldschool lead antimony batteries have a lower gassing voltage of abt 14.4V to start bubbling and getting fully charged, they take the same 1.265 SG electrolyte in them as the lead calcium ones. (hoping the manufacturer uses contact process product rather than cheapo oil of vitroil in there)

The lead calcium ones (usually termed maintenance free) have a higher gassing voltage of about 15 to 15.4V to start bubbling and be claimed fully charged. The one aspect of these batteries is that they dont lose electrolyte and are usually sealed off with push on caps.

If you look at a mercedes benz battery, it has removable caps for topping off the electrolyte and its a good idea to do that. - Also check the SG once in a while to see if its more than .010 points off from cell to cell. If it is then your battery is starting to develop internal problems.

Another factor is temperature of the battery. engine room heat can quickly kill a battery, and Im usually surprised that the thermal sleeve provided by the manufacturer is usually thrown out at battery change (dealerships included) - I have got a few of them for toyota/nissan etc. for free at the dealer just by asking if they have any of those sleeves in the trash.

The sleeves are not useful in later benz as the battery is protected by a false firewall or its in the cabin, the early ones can benefit from it (like a 115 chassis etc)

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

All valid points. One thing I would add though. Every now and then, put a digital voltmeter across the battery with the engine running. It should read about 13.5 to 14.5 volts depending on level of charge. If the voltage goes higher than 14.5 or so and is not significantly discharged, investigate. High charge voltage will fry the battery. Also if you are popping light bulbs a lot, you should check for excessive charging voltage.

Inexpensive DVM's are readily available these days. Keep one in your toolbox and check charge voltage occasionally.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

My experience with batteries the last 20 or so years is that if they are low on water they are already pretty well done.

My 03 Dodge's factory batteries lasted 11 years and nearly 200K miles and were not actually bad when I replaced them they were just beginning to fall off a bit.

My 012 VW TDI otoh has 'bout 5 years and 90K miles on it and I just found out today the battery is shot.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I keep a bottle of distilled water in the garage along with a clean turkey baster for battery maintenance. I have only had to add once. I also check very very regularly for corrosion at the terminals. After suffering a while with iffy battery connections and corroded wires, I had to get a new set of cables made for my truck. On my car, it does not look like a fun process to have new cables made and I will not use clamp on cheap-O terminals you get at the parts store.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

Basic to Advanced Battery Information from Battery University

Very long but appropriately informative. Lots of info on how to charge various battery chemistries, lifetimes etc....should be more relevant as more and more things become battery powered.....

-John

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2009 Kia Sedona
2009 Honda Odyssey EX-L
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(insert Mercedes here)

Husband, Father, sometimes friend =)