Eurochron EFWS 91 i Mode D'emploi page 45

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Always exchange the entire set of batteries/rechargeable batteries, only use
batteries/rechargeable batteries of the same type and by the same manufacturer
with the same charge status (do not mix full with semi-full or empty batteries/
rechargeable batteries).
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Never mix normal batteries with rechargeable ones. Either use batteries or
rechargeable batteries.
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Regarding environmentally compatible disposal of batteries and rechargeable
batteries, please read the chapter on „disposal".
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