kuksul08
Enlightened
It's been a while since I've posted here. I currently have an LED bike light that I made with the help of this site :thumbsup:. It has an MCE (2A, 4P) and an XRE (.7A), for a total current draw of about 2.7A. Each is controlled individually with a switch.
My power supply has two configurations: 4S or 4S2P, which are Eneloop AA batteries - so, each cell will either see 2.7A or 1.35A depending on configuration. I made it this way, so if I don't have 8 fully charged batteries, I can always grab 4.
I understand the benefits of a higher voltage system - less strain on components, smaller wire needed, etc... but it can be hard to manage a higher voltage and light configurations without more complex circuitry. I am using AMC7135 linear regulators. (One might daisy chain them, but that's not the point here unless you have some suggestions :shrug
Anyway... in search of more light (as we all are), I have been playing with the idea of a dual MC-E, or quad XR-G yadda yadda. The end result, with my current power supply, is more current draw on the batteries. I won't get too specific since nothing is decided, but upwards of 6A or so wouldn't be unreasonable.
My question is - how does battery life suffer with a larger current? I am looking into long term (such as over a long period of time, the number of discharge and charge cycles), and short term (such as battery life over one discharge cycle). On paper, it makes no difference at all. Capacity is capacity, power drawn can give you the theoretical run time no matter what... but in real life, there is the internal resistance, and I'm sure some changes in battery chemistry as a result of high current draw. Heat is also an issue. With Li-Ions, they can explode... but that's all I ever hear about.
I know that went on and on! I tried to set it up so you know my situation. Hopefully someone has the time to read it and offer some advice :twothumbs
*Note: Currently, the batteries have been staying cool when in the 4S2P configuration until the very end (voltage drops 1.2 to .9), they become luke warm. It's barely noticeable.
My power supply has two configurations: 4S or 4S2P, which are Eneloop AA batteries - so, each cell will either see 2.7A or 1.35A depending on configuration. I made it this way, so if I don't have 8 fully charged batteries, I can always grab 4.
I understand the benefits of a higher voltage system - less strain on components, smaller wire needed, etc... but it can be hard to manage a higher voltage and light configurations without more complex circuitry. I am using AMC7135 linear regulators. (One might daisy chain them, but that's not the point here unless you have some suggestions :shrug
Anyway... in search of more light (as we all are), I have been playing with the idea of a dual MC-E, or quad XR-G yadda yadda. The end result, with my current power supply, is more current draw on the batteries. I won't get too specific since nothing is decided, but upwards of 6A or so wouldn't be unreasonable.
My question is - how does battery life suffer with a larger current? I am looking into long term (such as over a long period of time, the number of discharge and charge cycles), and short term (such as battery life over one discharge cycle). On paper, it makes no difference at all. Capacity is capacity, power drawn can give you the theoretical run time no matter what... but in real life, there is the internal resistance, and I'm sure some changes in battery chemistry as a result of high current draw. Heat is also an issue. With Li-Ions, they can explode... but that's all I ever hear about.
I know that went on and on! I tried to set it up so you know my situation. Hopefully someone has the time to read it and offer some advice :twothumbs
*Note: Currently, the batteries have been staying cool when in the 4S2P configuration until the very end (voltage drops 1.2 to .9), they become luke warm. It's barely noticeable.
