Can de-ionized water be used instead of distilled water to prepare lead acid battery electrolyte?
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 ;-)