I have a bunch of budget flashlights from Amazon and Walmart, along with different battery manufacturers.
The 2 name brand batteries I have are KEEPPOWER and VAPCELL. The other brands are whatever came with the flashlight. Particularly good(testing via Opus charger) are the batteries that came with PHIXTON flashlight and SPRIAK lights, both tested to over 5000mAH.
I was checking the draw on the batteries with my VOM, and it seemed to me some batteries drew more power than others.
Tested Peak
MFR Voltage Amps Calculated Watts Battery Notes
Phixton 4.2 2.8 11.76 6000mAH w/o max output rating(5500mAH measured)
Vapcell 3.9 2.5 9.75 6200mAH 22.9 WH, 15A
Keeppower 4.0 2.3 9.2 5500mAH 19.8 WH, 6A
By PEAK VOLTAGE, this is the highest voltage my VOM was reading as the draw was oscillating(assuming due to the power circuit)…not sure if there is a better way to measure without a wattmeter.
I am curious if this is to be expected. All batteries are 26650.
Sorry that the table is ugly…hints to make a better table also appreciated.
GENERALLY (ie, there are of course exceptions, but…) higher capacity cells are optimised for that, but can’t dump as much current as those lower-capacity cells which are optimised for max current. Just like a car engine can be smaller and tweaked for efficiency but can’t go hauling a horse-trailer, vs a big donk of a V8 that oozes power but is rather thirsty.
In a flashlight, at lower currents there’s not much difference, but once you crowbar the LED across the cell (ie, “turbo”), the high-cap/low-current cell will drop in voltage (series resistance is high thus drops its own voltage) and thus current will be lower, but a low-cap/high-current cell has minimal series resistance, doesn’t drop as much voltage, so hits the LED with more voltage thus more current.
Same reason why 3×AAA lights don’t instantly fry the anæmic LEDs that’re used, even though they should be seeing 4.5V, but the LED voltage drop so 3.2V or whatever so that total draw is maybe 200mA. That 1.3V drop is in the AAAs themselves due to their huge series resistance, and only gets worse as they get spent.
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This?
| MFR | Voltage | Amps | Calculated Watts | Battery | Notes |
|---|
| Phixton | 4.2 | 2.8 | 11.76 | 6000mAH | w/o max output rating(5500mAH measured) |
| Vapcell | 3.9 | 2.5 | 9.75 | 6200mAH | 22.9 WH, 15A |
| Keeppower | 4.0 | 2.3 | 9.2 | 5500mAH | 19.8 WH, 6A |
Manually tagged, guessing that’s what you wanted?
Thank you sir…how do you dooooo it?
Confuse even people that have been at it for years!
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LB mentions battery resistance of high capacity cells vs high current cells which is one of the major factors. One of the minor factors is the cell resistance is fluid and varies depending on how full/depleted the battery is. Heat can also play a part. Not sure if it’s still a thing but among rc groups someone once in a while would get a fire due to thermal runaway. To my knowledge thermal runaway has never been an issue for flashlights.
Wasn’t that an issue of the internal chemistry, ie, ICR vs IMR vs IFR vs INR, etc.?
Think ICRs (cobalt) were most prone to runaway, but I think they’re also pretty rare nowadays.
Yeh, you’re probably right. And i probably shouldn’t have mentioned it since it’s a non issue anyway
Naw, there might still be ICRs floating around. Laptop pulls, etc.
Even if that was true i haven’t heard of any ‘disasters’ from thermal runaway in a while. Also it’s not that relevant to OP’s question
Did you test with all the cells starting at the same voltage? Cell voltage makes a massive difference when it comes to linear or FET driven lights (LEDs will allow more current through when they have a higher voltage across them)