I have a couple of Yuasa and Power Sonic conventional lead-acid bike batteries that I recently purchased for a very good bargain price from a seller. They are new and never used. But unfortunately, the seller did not have the battery acid packs in his possession. So, I have to end up preparing that myself.

I know that I'll need to prepare a 36-38% concentrated sulfuric acid solution (this is what manufacturers usually use) using my concentrated acid which is a 95-98% ACS reagent sulfuric acid.

Now I know that they usually use distilled water to prepare them. But I was thinking if it's possible to use ultrapure de-ionized water instead.

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    \$\begingroup\$ As a chemist, I say yes. \$\endgroup\$
    – Ed V
    Commented Apr 29, 2020 at 17:11
  • \$\begingroup\$ As an electrical engineer I say trust the chemist. \$\endgroup\$ Commented Apr 29, 2020 at 17:23
  • \$\begingroup\$ @EdV Thaks for the response. I was looking for assurance before I went ahead and prepared it since I didn't want to mess up the process. BTW which one is a better choice if you had to choose among them, distilled or deionized? \$\endgroup\$ Commented Apr 29, 2020 at 17:26
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    \$\begingroup\$ Yes but remember the order, add acid to water! \$\endgroup\$
    – John D
    Commented Apr 29, 2020 at 17:26
  • 1
    \$\begingroup\$ Great! Then I strongly second what @JohnD advised. All the safety gear is essential and stir well (glass stirring rods are good) as you very slowly add the acid to the water. \$\endgroup\$
    – Ed V
    Commented Apr 29, 2020 at 18:21

1 Answer 1


Either type will work (deionized [DI] or distilled.) Both have had most mineral contaminants removed; DI more so than distilled. DI however is overkill, as distilled easily meets acceptable contaminant limits for lead-acid batteries.

More here: https://www.trojanbattery.com/pdf/WP_EffectOfImpurities_0612.pdf

So, ask the battery maker who employs the chemist ;-)

  • \$\begingroup\$ (+1) Nice reference! I especially liked the thing about platinum as a water impurity! \$\endgroup\$
    – Ed V
    Commented Apr 29, 2020 at 18:34
  • \$\begingroup\$ Thanks for sharing the link. That was very informative. So, one manufacturer also suggests it is safe to use deionized water. In parallel, I had emailed Yuasa technical support two days ago to see what they have to say about this. Since one of the brands I have is from them. I just got a response a few minutes ago. Their engineer seems to suggest that I use only distilled water only. I guess maybe it's because that's what they use in the manufacturing process. But after reading the article you have added above and from @EdV response I'll go ahead with deionized water. \$\endgroup\$ Commented Apr 29, 2020 at 19:21

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