Not sure on the explorer. The etrac I charge overnight. I also got rechargeable batteries and put them in the alkaline battery pack. They are Duracell and those take about 2 hours to charge. They have the green light that lets you know when they are charged. My factory rechargeable battery pack never gives you an indication when its charged but I have heard they are engineered to not overcharge. I hope this helps you some. Maybe someone with an explorer can chime in. Which explorer do you have, the se pro, xs, ?
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