Tobias Bossert
Newly Enlightened
This thread is for caving LED lights, since the requirements of cavers seem to differ highly from most threads in CPF.
Most CPF members seem interested in maximum peak light output out of a minimum space and weight. Many modifications of professional flashlights discussed here result in very high light flux with the price of short burn time. Almost all flashlights DIY mentioned in CPF are specialized on these requirements.
My hobby is exploring large caves, where i'm used to stay for two to five days continuously. Cavers used carbide lights so far. Now batteries and LEDs are advanced enough to be used as a primary light source. There are many headlamps on the market, professionally produced and acceptable in price. But most of them are far away from being optimized for caving needs!
Cavers need three different lightning modes:
I use a SSC P4 USVNI with a mobdar (Gaggione LL3) as short time spotlight with a single level 16mm board bearing two AMC7135. The working light is a SSC P4 S2SJ1H without optics with a three level 16mm board bearing one AMC7135 and a PIC12F269. Using one single rechargeable Li-Ion 18650 (2200mAh) this working light is constant 350mA over a period of about 6 hours under cave conditions. Two such cells in parallel hold all over one caving day generously. With three primary Li-Fe AA cells (2900mAh) in series it holds over one caving day only just.
The problem seems to be solved so far, but...
Many cavers don't like to use exotic cells for caving proprietarily. They prefer to use AA alkaline or NiMH as they are used with most other devices. Unfortunately voltage levels of alkaline and NiMH batteries mismatch to Vf of white LED.
The average temperature in our alpine caves (Austria, Germany, Swizerland) is 0 to 5°C. Under such conditions 3 AA alkaline or normal NiMH cells fall short and 4 cells in series are needed at least. But with 4 cells efficiency of linear regulation is poor, because average input voltage is much too high. Additionally heating is inacceptable, especially when you newly enter the cave with fully charged or fresh batteries being still worm from outside.
4 NiMH provide still sufficiently low voltage drop under cave temperatures to be discharged completely, but 4 alkaline drop below 3,6V long before being empty. Under cave conditions you will need 5 or 6 alkaline in series, otherwise you will have to replace them still half full. Therefore a step down converter is needed.
For the spotlight no multilevel is required. Shoppe SOB750, Kai SKU2982 or DX SKU3256 / 4255 may be applicable for example.
But as far as I can see, no multilevel low power step down converter board is on the market at the moment, serving for our work / reserve light reasonably. I'm not willing to develop a new board by my own, since few devices will be needed only.
Does anyone know a multi level step down board with appropriate specifications?
Kind regards
Tobias
Most CPF members seem interested in maximum peak light output out of a minimum space and weight. Many modifications of professional flashlights discussed here result in very high light flux with the price of short burn time. Almost all flashlights DIY mentioned in CPF are specialized on these requirements.
My hobby is exploring large caves, where i'm used to stay for two to five days continuously. Cavers used carbide lights so far. Now batteries and LEDs are advanced enough to be used as a primary light source. There are many headlamps on the market, professionally produced and acceptable in price. But most of them are far away from being optimized for caving needs!
Cavers need three different lightning modes:
- Spotlight with high flux in a narrow beam to be used for short time only (some minutes)
- Working light for about 8 hours a day, LED without optics, aim is 100 lm constant
- Reserve light for another 8 hours a day, LED without optic, 10 lm is strong enough
I use a SSC P4 USVNI with a mobdar (Gaggione LL3) as short time spotlight with a single level 16mm board bearing two AMC7135. The working light is a SSC P4 S2SJ1H without optics with a three level 16mm board bearing one AMC7135 and a PIC12F269. Using one single rechargeable Li-Ion 18650 (2200mAh) this working light is constant 350mA over a period of about 6 hours under cave conditions. Two such cells in parallel hold all over one caving day generously. With three primary Li-Fe AA cells (2900mAh) in series it holds over one caving day only just.
The problem seems to be solved so far, but...
Many cavers don't like to use exotic cells for caving proprietarily. They prefer to use AA alkaline or NiMH as they are used with most other devices. Unfortunately voltage levels of alkaline and NiMH batteries mismatch to Vf of white LED.
The average temperature in our alpine caves (Austria, Germany, Swizerland) is 0 to 5°C. Under such conditions 3 AA alkaline or normal NiMH cells fall short and 4 cells in series are needed at least. But with 4 cells efficiency of linear regulation is poor, because average input voltage is much too high. Additionally heating is inacceptable, especially when you newly enter the cave with fully charged or fresh batteries being still worm from outside.
4 NiMH provide still sufficiently low voltage drop under cave temperatures to be discharged completely, but 4 alkaline drop below 3,6V long before being empty. Under cave conditions you will need 5 or 6 alkaline in series, otherwise you will have to replace them still half full. Therefore a step down converter is needed.
For the spotlight no multilevel is required. Shoppe SOB750, Kai SKU2982 or DX SKU3256 / 4255 may be applicable for example.
But as far as I can see, no multilevel low power step down converter board is on the market at the moment, serving for our work / reserve light reasonably. I'm not willing to develop a new board by my own, since few devices will be needed only.
Does anyone know a multi level step down board with appropriate specifications?
Vin = 3V to at least 9 V
Iout = about 350mA switchable to about or even below 35mA with reasonable efficiency
Vout = 3,0 to 3,5V
Is there any other caver in CPF home building or modifying cavers LED-headlamps?
Kind regards
Tobias