Just like this;
And seeing you got those nasty firecrackers, I mean batteries, I would recommend installing one of these in the other wire in line like your switch;
You want a NC (normally closed) 70 degree, comes in pairs for just over a dollar, these are automatic resetting thermal fuses (cuts power if it gets too warm and will automatically reset when cool) cheap insurance for those batteries.
And seeing you got those nasty firecrackers, I mean batteries, I would recommend installing one of these in the other wire in line like your switch;
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