I have a motion sensor spotlight that uses 4 D-size batteries. The motion sensor trips a lot — too much. I changed the batteries 2 times since I got the unit (about 3 months ago). To save costs, I’ve replaced the alkaline batteries with rechargeable NiMH batteries.
D-size batteries are considerably larger than AA. It’s not just wider, but taller. The insert compensates by having an extension contact at the top and a bottom spacer with another contact. The battery fits snuggly in its case.
So far, the battery output is strong enough to power the sensor and the lights. Looks to be a win on this lifehack.