I started with a $3 lantern flashlight from Walmart, installed a 1 watt replacement LED, a 4 D cell carrier, and 4 NiMH 10ah batteries. I have gone a full year of regular use, and just swapped the batteries for another charged set, and put the old batteries in the charger for next year.
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Lantern Flashlight - $7
1 Watt LED replacement bulb (constant brightness) - $16 (never have to change this)
4 D Cell Adapter - $3.50
10ah NiMh D Cell (x4) - $5.20 each
Tenergy Advanced Universal Charger TN190-4 Channel AA/AAA/C/D/9V Ni-MH Charger with LCD Display and USB Power Outlet - $30 (smart charger, solar and auto ready)
Step 1: Lantern Body
There's no prep work, except to remove the battery if it's installed, and the existing light bulb. Keep any small parts that hold the bulb in place.