deionized water versus distilled water

Not a lot of difference, distilled water comes from a still, which boils water tnto steam, then condenses it back. This removed all the product which do not boil , but it is possible for some vapors to be condensed along with th water. Deionized water is processed through a series of mechanical and chemical filters, which electronically and chemically remove everything except pure H2O. It is more difficult to find, as it is a bit more difficult to produce. However, really deionized water is almost a perfect insulator, and WILL NOT conduct electricity at all. Having said that, note that ANY impurities added to the water will destroy the insulation properties, and make it an almost perfect conductor. For batteries, if you can get it, deionized water is the better choice, but most folks use distilled instead. There should be no noticible difference.

Rated by the amount of DISSOLVED SOLIDS as measured Parts per Million. Water purification businesses do not dare fib about this number. Lowest number approaching zero is best.

Deionized water is certainly better than tap water, but can still may contain many impurities. Distilled water is purer, and better for battery use.

Doug

Deionized water is no better than distilled water for use in batteries.
It can be produced by ion exchange resin cartridges or reverse osmosis according to Wikipedia.
Tap water can shorten the life of batteries according to the battery manufacturers, so using distilled, DI or OR water in batteries is a good idea as far as I am concerned.

I get distilled water for my CPAP humidifier and batteries at Walmart for less than $1 per gallon. RO/DI water has been higher when I looked at the prices.