USB Charging Through Cell, Light, or External

Dnuts

Newly Enlightened
Joined
Dec 25, 2015
Messages
8
Just recently got the itch to get back into flashlights again :D

I'm a bit apprehensive about lithium cells but I recognize they open up a whole new world of possibilities and I'm just trying to get a gauge on some of the new things I see.

With a lot of the lights I'm seeing, either the cell itself or the light has a USB charge port on them. I don't envision that I'd be carrying around an external charger or DMM everywhere I may be charging up given it has a USB port built right in.

Are cells/circuitry better these days in the sense that you don't necessarily need to always use an external charger and check with a DMM every time? I recall this being the standard advice back a few years ago.

Thanks!
 

Lynx_Arc

Flashaholic
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Oct 1, 2004
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11,212
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Tulsa,OK
I have all 3 types of charging options and don't check with a DMM every time. Realistically you only need to check the first time you use the charger setup. There are advantages and disadvantages of all 3 options.
Built in charger: Advantage - not needing external charger and able to use to charge other cells. Disadvantage: Unable to use light while recharging cells if it is your only charging choice
USB cell charging: Advantage - not needing external charger, able to recharge cell while using another cell in light. Disadvantage: You can only recharge the one cell itself with the charger needing an external charger to charge other cells
External charger: Advantage - able to charge cells while using light with other cells. Disadvantage: Bulkier and requires removing cells to charge them (only option that has advantage over this is built in charging.
IMO I recommend having 2 options on lights or external chargers if only one option.
 
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WalkIntoTheLight

Flashlight Enthusiast
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Jun 18, 2014
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3,967
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Canada
Unless you're a bit of a battery geek, built-in USB charging is simpler, easier, and sufficient for most people. It does add size and weight to the light, which could make a difference for a EDC flashlight. It often also results in a light that is less waterproof, but should still be fine for rain.

If you're a bit of a battery geek, external charging gives you more flexibility in how you charge, what level you charge up to, monitoring the health of your battery, etc. It's also a bit safer, since you're presumably using a better charger than a built-in version, and if the battery does explode, it's not in an enclosed metal case. But, that's a very unlikely scenario, so you probably shouldn't be too concerned about it.
 

Dnuts

Newly Enlightened
Joined
Dec 25, 2015
Messages
8
Thanks for the information folks, lots of good points and gives me some things to think about. I definitely would not stray from protected cells if I do take the plunge to Lithium. As recommended, I would also be checking with a DMM the first time I use the particular charger/cell combination or any time I change that up.

As for DMM tests, I know I can test to make sure the cell is between 3V and 4.2V before attempting charging. Then, once the cell is charged up, I know I can check to make sure the light/charging circuitry didn't charge past 4.2V.

Assuming the cell is protected, do you test to make sure that it won't over-discharge as well? I'm guessing you would run the light until it turns off then measure the voltage and check to make sure it's not below 3V? Or would the light automatically turn off even before then?

Thanks again!
 
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