power adaptor voltage output for MacBook A1181

My grandson is still using a MacBook 13" . the power adaptor is no longer working . I have the correct L mag safe end and want to determine the correct power adaptor voltage output at 3.5 amp so I can remove the battery from laptop and build an adaptor for him so he can continue using the laptop.

QA Apple MagSafe Power Adapter

QA Apple MagSafe Power Adapter

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