I've found a maxabeam without battery so I will need to build me one. I've built 18650 packs before (up to 12S4P) and I really like those cells. From what I've read the maxabeam needs at least 10V to run and max 13.5V input. This makes 18650 hard to use since a 3S pack would be max and then I can only discharge to about 3.3V/cell.
What at is my best options here? Is there any circuit I could use to drop voltage from a 4S 18650 pack down to regulated 13V efficiently or should I look into other types of cell.
Is anyone familiar with the connectors used by maxabeam? It looks like some kind of Amphenol plug.
I just got confirmation from Annie at peakbeam that 10-13.5VDC is the operating range but they say that powering it from the car will be fine due to voltage drop in the cables. I found a 15A stepdown from max 40V to 12V from polulu. It's rated for 32A peak current so that should work for lamp start. Efficiency with 15-20V input is around 95% so it should'nt be to bad loss. The step down can operate from 14.5V min so that rules out a 4S config. Since Peak beam has a 10Ah battery and I assume its 12V-ish thats 120Wh to use. Going with 5S3P with LG 18650 M36 3600mAh cell with approx 11.2Wh/cell at my load should give me 168Wh and counting efficiency loss of 6% around 158Wh. Since their 120Wh gives a lot of runtime I think this will be sufficient. Another benefit of using the stepdown is that the input voltage for the light will be the same from full to empty cells. Anyone see any problems here? I might look for a little bigger stepdown but 15A rated should really be fine when high beam is 8.5A. Going with panasonic NCR18650b would give the same numbers and load should be safely within the batteries spec on 3A/Battery but max 6,5A at startup is slightly above what panasonic recommends that's why I picked LG with 10A discharge.
step down - https://www.pololu.com/product/2885
Battery test : https://lygte-info.dk/review/batteries2012/LG 18650 M36 3600mAh (Cyan) UK.html
Maxabeam spec:
Low Beam Mode 3.38 ± 0.04 Amps 25°C, 12VDC Input
Normal Beam Mode 4.35 ± 0.04 Amps 25°C, 12VDC Input
High Beam Mode 8.48 ± 0.05 Amps 25°C, 12VDC Input
Peak Current at Lamp Start 20.5 ± 3.2 Amps 25°C, 12VDC Input
What at is my best options here? Is there any circuit I could use to drop voltage from a 4S 18650 pack down to regulated 13V efficiently or should I look into other types of cell.
Is anyone familiar with the connectors used by maxabeam? It looks like some kind of Amphenol plug.
I just got confirmation from Annie at peakbeam that 10-13.5VDC is the operating range but they say that powering it from the car will be fine due to voltage drop in the cables. I found a 15A stepdown from max 40V to 12V from polulu. It's rated for 32A peak current so that should work for lamp start. Efficiency with 15-20V input is around 95% so it should'nt be to bad loss. The step down can operate from 14.5V min so that rules out a 4S config. Since Peak beam has a 10Ah battery and I assume its 12V-ish thats 120Wh to use. Going with 5S3P with LG 18650 M36 3600mAh cell with approx 11.2Wh/cell at my load should give me 168Wh and counting efficiency loss of 6% around 158Wh. Since their 120Wh gives a lot of runtime I think this will be sufficient. Another benefit of using the stepdown is that the input voltage for the light will be the same from full to empty cells. Anyone see any problems here? I might look for a little bigger stepdown but 15A rated should really be fine when high beam is 8.5A. Going with panasonic NCR18650b would give the same numbers and load should be safely within the batteries spec on 3A/Battery but max 6,5A at startup is slightly above what panasonic recommends that's why I picked LG with 10A discharge.
step down - https://www.pololu.com/product/2885
Battery test : https://lygte-info.dk/review/batteries2012/LG 18650 M36 3600mAh (Cyan) UK.html
Maxabeam spec:
Low Beam Mode 3.38 ± 0.04 Amps 25°C, 12VDC Input
Normal Beam Mode 4.35 ± 0.04 Amps 25°C, 12VDC Input
High Beam Mode 8.48 ± 0.05 Amps 25°C, 12VDC Input
Peak Current at Lamp Start 20.5 ± 3.2 Amps 25°C, 12VDC Input
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