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Thread: Runtime on 2 CR123 vs 1 18650

  1. #1
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    Default Runtime on 2 CR123 vs 1 18650

    Hello,

    I want to understand something regarding batteries.

    Let say for a light with 100 lumen.

    2x CR123 (6v 1200 mah) vs 18650 (4.2v 2200 mah).

    Which provides more runtime? Would the higher voltage in the 2x CR123 compensate for the lack of MAH vs a 18650?

  2. #2
    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: Runtime on 2 CR123 vs 1 18650

    Quote Originally Posted by dealgrabber2002 View Post
    Hello,

    I want to understand something regarding batteries.

    Let say for a light with 100 lumen.

    2x CR123 (6v 1200 mah) vs 18650 (4.2v 2200 mah).

    Which provides more runtime? Would the higher voltage in the 2x CR123 compensate for the lack of MAH vs a 18650?
    We look at things in watt/hours: Wh.

    Most of the US made CR123A (Panasonic USA) are about 1500mAh @ 3.0v (3.25v out of the pack.)

    I'm going to guess that 100LM on an XM-L2 might be around 300mA: 3A @ 1050-ish LM.

    Nominal voltage on an 18650 li-ion is 3.6v/3.7v (50% SOC) and we have common 10A ~3500mAh cells out there.

    Is the light regulated, or direct drive?

    I'll just throw out 5 hours for the 6v CR123A combo and 4 hours on the 2200mAh 18650.

    I'm guessing on a lot of stuff.

    Chris
    Convoy: S2, S2+, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, XP1, MC1+, WP2 II, NiteCore i4, v2.

  3. #3
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    Default Re: Runtime on 2 CR123 vs 1 18650

    I just ordered a Fourseven QB2L-X which runs on 2x CR123, but I have lots of 18650s, so I was just curious.

  4. #4
    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: Runtime on 2 CR123 vs 1 18650

    Quote Originally Posted by dealgrabber2002 View Post
    I just ordered a Fourseven QB2L-X which runs on 2x CR123, but I have lots of 18650s, so I was just curious.
    The only issue would be whether the QB2L's output suffers on the 18650, since it will have a nominal voltage of 3.6-7v, but would be 4.2v hot off the charger. Many lights that are designed to run on 6v (2*CR123As) can still perform adequately with an 18650 li-ion, but there's only one way to know for sure.

    Chris
    Convoy: S2, S2+, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, XP1, MC1+, WP2 II, NiteCore i4, v2.

  5. #5
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    Default Re: Runtime on 2 CR123 vs 1 18650

    Read it has a buck driver, not sure would that help much.

  6. #6
    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: Runtime on 2 CR123 vs 1 18650

    Quote Originally Posted by dealgrabber2002 View Post
    Read it has a buck driver, not sure would that help much.
    I think that bucking down from 6v to <4.2v is the more efficient way to go about it, so runtimes would appear to benefit, but I'm an English Lit./Comm. guy and I didn't sleep at a Holiday Inn last night.

    Chris
    Convoy: S2, S2+, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, XP1, MC1+, WP2 II, NiteCore i4, v2.

  7. #7
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    Default Re: Runtime on 2 CR123 vs 1 18650

    Thanks ChrisGarrett.

  8. #8

    Default Re: Runtime on 2 CR123 vs 1 18650

    2 Panasonic CR123's are going to have roughly 8 Wh (4 WH each).

    a single 2.2 Ah 18650 will have roughly the same 8 Wh (give or take about 1 Wh depending on the specific 2200 mAh cell), though it will likely be a bit more efficient with typical LEDs that draw 3-3.5 Volts, while the 2 CR123s at 6 V in series will need a driver to reduce the Voltage which will lose some power. On the other hand with CR123 primaries, you can run them down until they are fully drained, unlike 18650's which must not be over discharged.

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