No, battery water is (usually) aqueous sulfuric(VI) acid, H2SO4(aq).
All batteries are Galvanic/Voltaic cells which require a conducting solution (ie. electrolyte) to generate electricity. Cars use the lead-acid battery. At the anode, Pb(s) is oxidized to PbSO4(s). At the cathode, PbO2(s) is reduced to PbSO4(s). The lead-acid battery is rechargeable (ie. called a secondary cell) because the PbSO4(s) generated remains in contact with both electrodes. Finally, a battery is actually a series of Galvanic/Voltaic cells.
More info :
http://en.wikipedia.org/wiki/Lead–acid_battery
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Deionized water is water with (almost) all ions removed, with the use of various deionizing technologies.
Theoretically and ideally, both deionized water and distilled water = pure water.
But in practice, because the deionization process and the distillation process are different, there will inevitably be some impurities in both, hence neither deionized water not distilled water, is truly 100% pure water.
For more info :
http://www.distilleddeionizedwater.com/deionized-water-vs-distilled-water/
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Having said all that, sorry I do not know where/who/which company in Singapore is a reliable source of either deionized water or distilled water.
Anyone know where TS can buy deionized / distilled water for cleaning his "presion probe"?