cityevader
Enlightened
Hello,
I'm building a dual P7 bike headlight, which will be on independent switches so one or the other or both can be on. Additionally, If a single one is bright enough, then one lamp will go on the other bike. So battery configuration must be compatible (i.e. leds can't be in series, same battery setup whether one lamp or two). A driver will be in each lamp. And I'll be using the integrated switches (Performance Viewpoint/Marwi setup) for on/off so nowhere aesthetically pleasing to put momentary switch for multi-mode.
I'm having a real hard time deciding on cell configuration. I really like the idea of an 18650 parallel pack for capacity (any number of batteries added depending on length of ride) and single cell emergency use. What are the advantages/disadvantages of a 4p1s 3.7v pack with, say a few amc7135 paralleled to get 2.1A to each LED, compared to 2s2p 7.4v pack with a couple of buck convertors (one each led)
I like the idea of cheaper 7135 but like the idea of buck getting full brightness over the full capacity of battery. (I'm not sure exactly what bin and Vf P7 I got from hoffmanamps.com, so unsure how long 7135 setup would get full brightness before it started dimming). I don't really want a sudden loss of light when end of battery reached.
Some other concerns:
I definitely do not like the idea of stripping down a pack for individual cell recharging (especially if I'm doing it for both our bikes simultaneously), nor do I like the idea of spring-loaded holders. I'd like to solder the cells, but can't find protected ones with solder tabs. If a 4p1s made, can a single pcb protect all 4 cells?
If 4s1p then I'd need to figure out/add a balancing pcb. Then a more expensive "smart charger" for multi volatage range packs will be needed if I change configuration later, say from 7.4 to 11.1v.
I've done so much researching here on CPF that I actually feel like I know less now!! Any input will be appreciated.
I'm building a dual P7 bike headlight, which will be on independent switches so one or the other or both can be on. Additionally, If a single one is bright enough, then one lamp will go on the other bike. So battery configuration must be compatible (i.e. leds can't be in series, same battery setup whether one lamp or two). A driver will be in each lamp. And I'll be using the integrated switches (Performance Viewpoint/Marwi setup) for on/off so nowhere aesthetically pleasing to put momentary switch for multi-mode.
I'm having a real hard time deciding on cell configuration. I really like the idea of an 18650 parallel pack for capacity (any number of batteries added depending on length of ride) and single cell emergency use. What are the advantages/disadvantages of a 4p1s 3.7v pack with, say a few amc7135 paralleled to get 2.1A to each LED, compared to 2s2p 7.4v pack with a couple of buck convertors (one each led)
I like the idea of cheaper 7135 but like the idea of buck getting full brightness over the full capacity of battery. (I'm not sure exactly what bin and Vf P7 I got from hoffmanamps.com, so unsure how long 7135 setup would get full brightness before it started dimming). I don't really want a sudden loss of light when end of battery reached.
Some other concerns:
I definitely do not like the idea of stripping down a pack for individual cell recharging (especially if I'm doing it for both our bikes simultaneously), nor do I like the idea of spring-loaded holders. I'd like to solder the cells, but can't find protected ones with solder tabs. If a 4p1s made, can a single pcb protect all 4 cells?
If 4s1p then I'd need to figure out/add a balancing pcb. Then a more expensive "smart charger" for multi volatage range packs will be needed if I change configuration later, say from 7.4 to 11.1v.
I've done so much researching here on CPF that I actually feel like I know less now!! Any input will be appreciated.
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