Can rainwater be used in car batteries?

(2011-12-03 15:20:17)

1. RALPH Says: They say that some used rain water in replacement for the water in car batteries, How effective is it?

2. Ramon C Says: NO!!!!! The same reason you cannot use tap water. It is not pure enough. Batteries need extra clean water. You can buy distilled water anywhere and that is the only water to add. There is acid in there and this combo is what produces electricity to start the car. Adding other than distilled water will shorten the life of the battery.

3. Claira Voyant Says: It's better than nothing, but if you have nothing in there then you have another problem, like a bad battery or an overcharging charging system. It is best to use distilled water for sure, but clean bottled water can be ok in a pinch. Rain water isn't as clean as it may seem, and the contaminants in it could (but probably won't) damage the battery. The liquid in a battery starts out at 60% sulfuric acid (really nasty stuff) and 40% water; the water can boil off if overcharged, and the gasses involved cause the corrosion that you see on some batteries and cables. The biggest thing is to make sure the liquid level is always above the lead plates; but most batteries are sealed, making this a moot point. If you do add water often, you likely need a new battery anyway.

4. theharleyfixer Says: NO!!!.....DISTILLED water ONLY.

Rain water, tap water, even regular bottled water are big no-no's. These all contain contaminants, minerals, etc that will cause sulphuric corrosion inside the battery.

Initially, battery acid, a special dilution of sulphuric is added to the battery, this causes the chemical reaction with the lead plates inside the battery. The lead absorbs the acid, the liguid left inside is water, which over time, on cheaper and old-style non-sealed / non-mainteance free batteries, will evaporate, causing the need to add more water. The water added MUST be distilled, which is 100% pure with no contaminants. Distilling is basically super-heating and boiling the water, capturing the the steam in a sterile container and letting it condense back into pure water.

Also note....NEVER add more acid...ONLY Distilled water.

The same thing is true for adding water to your radiator and diluting anti-freeze/coolant.