Originally Posted by incrediboy729
Are you using these in a flashlight? If you are, be careful. Some types will have an actual voltage of 3.5 to 4v and can blow a normal bulb, if your bulb is LED you should be OK. I would test them with a voltage meter first, a SF battery will read about 3.1v.
Most lithium-ion rechargeable cells are 3.6V under load, a fresh 3.6V will read about 4.2V, which is why most Xenon bulbs are rated at 9V and LED drivers running 2 cells at 8.4V. Running an LED does not make it any less susceptible to damage from over voltage, the emitter may not 'burn out' as incandescents but will still be destroyed.