PM6 w/123s
- Thread starter kd7kmp
- Start date
KevinL
Flashlight Enthusiast
The way to determine if a BB or DB will work with rechargeable 123s all lies in the voltage.
R123s have a peak voltage of 4.2V fresh off the charger and a nominal voltage of 3.7-3.8V. For our calculations we'll assume peak voltage, since Bad Things(tm) could happen if you assume too little voltage.
BB/DB converters must work within a certain voltage range to be effective. This voltage range is in part determined by the LED. For your BB, its job is to raise the voltage to the Vf required by the LED - in the case of a 5W LED, its Vf can be taken to be around 6.5-7V. If you supply the converter with an input voltage HIGHER than the Vf of the LED, the converter goes into direct drive and may cook the LED. Thus you should always feed it less volts than the Vf of the LED. 2 x 4.2V = 8.4V, too much. 1 x 4.2V should work, you will need a dummy spacer to take the place of one of the 123 cells.
The DB works the opposite way. Its job is to lower the input voltage to the voltage that the LED requires. The 3W Luxeon's Vf is around 3.6-3.9V, so anything above that will be fine, up to the maximum limit of the converter. If you supply it less Vf than the LED requires, it will also drop into direct drive mode, but since this case will be underpowering the LED rather than overpowering it, you'll just get a very dim light. dat2zip (the creator of the converters) has said that they will tolerate 3 x R123s (up to ~12V) safely.
R123s have a peak voltage of 4.2V fresh off the charger and a nominal voltage of 3.7-3.8V. For our calculations we'll assume peak voltage, since Bad Things(tm) could happen if you assume too little voltage.
BB/DB converters must work within a certain voltage range to be effective. This voltage range is in part determined by the LED. For your BB, its job is to raise the voltage to the Vf required by the LED - in the case of a 5W LED, its Vf can be taken to be around 6.5-7V. If you supply the converter with an input voltage HIGHER than the Vf of the LED, the converter goes into direct drive and may cook the LED. Thus you should always feed it less volts than the Vf of the LED. 2 x 4.2V = 8.4V, too much. 1 x 4.2V should work, you will need a dummy spacer to take the place of one of the 123 cells.
The DB works the opposite way. Its job is to lower the input voltage to the voltage that the LED requires. The 3W Luxeon's Vf is around 3.6-3.9V, so anything above that will be fine, up to the maximum limit of the converter. If you supply it less Vf than the LED requires, it will also drop into direct drive mode, but since this case will be underpowering the LED rather than overpowering it, you'll just get a very dim light. dat2zip (the creator of the converters) has said that they will tolerate 3 x R123s (up to ~12V) safely.
