Review on Miniature White LED Flashlight Bulbs Lamps by Dewitt Bhattacharya

Performance is ok but rechargeable batteries are not the best choice for these lights. So this limits the gain in efficiency if you have to go back to using disposable batteries. A fresh set of alkaline batteries will give you a nice bright white light; and they should last a long time (I haven't tested the battery life). But while an alkaline battery has an initial voltage of about 1.6 volts, depending on which battery you use, a typical freshly charged rechargeable battery will be 1.4, more or less, and the bulb will be significantly less bright. I suspect the reviewers say the bulbs are dimmer than an incandescent bulb, perhaps with rechargeable batteries or partially discharged alkaline batteries. Based on testing different batteries at known voltages it appears that the bulb can be brighter as the voltage drops below 1.35-1.30. For example, an incandescent bulb with batteries below 1.2V will still produce enough light for my toddler to play with under his ceiling fort. This LED lamp does not emit any light at all at this voltage. If you are using alkaline batteries this seems to be a good lamp. It won't work as well if the battery is dead, but it will take longer to get to that point than with a regular incandescent bulb. If you want to use batteries, this is a mixed bag. You may need to charge the batteries a little more often than planned. The low power consumption should compensate for this. But you'll never get the same bright light from freshly charged batteries as you would from a fresh set of alkaline batteries. If you need super bright light, add a set of disposable lithium batteries, which typically start at 1.8V.