AA lithium power density

how does the AA lithiums' compare to the 123's in high drain?

I should guess that they are even better because they have more capacity and they are thinner so the heat can escape easier.

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AilSnail said:
how does the AA lithiums' compare to the 123's in high drain?

I should guess that they are even better because they have more capacity and they are thinner so the heat can escape easier.


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An AA and a 123 have almost identical volume. The 1.5V L91 AA performs much better at high loads than a CR123 as measured by deliverable Whr. Each type has a PTC overcurrent protection device. The L91 PTC will trip at a lower power delivery than a CR123.

If it can perform better, I wonder why do they make it trip at a lower power delivery level than the CR123. Hmm...

Glad to hear that. I havent had any 123 shut down due to overcurrent yet, even though I have flashed them often (>8A). Or is it sort of a variable resistance thing and not a sudden shut-down? I guess the better high load performance will be offset somewhat by the lower conversion efficacy from <1.5V with a madmax.

Not much difference in capacity after all (mind slip).

Dang, it seems the 1.5v lithium AA's (L91) are the only ones available for cheap (~$2)? How much for the 3v's, and how do these compare in high drains?

AA lithium energy capacity (1.5 volts, 2800 mAH = 4.2 WH) isn't that much different from 123 capacity (3 volts, 1300 mAH = 3.9 WH). The AA's cost a lot more than the 123's though.

Highest energy density in a commonly available lithium is probably from the CR2450 coin cell, 650 mAH and around 6 or 7 grams. It would be nice if someone made a Photon-like light around one.

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Nerd said:
If it can perform better, I wonder why do they make it trip at a lower power delivery level than the CR123. Hmm...

[/ QUOTE ] The PTC devices have there trip points based on current, not power. The L91 is rated for 2A continuous, the CR123 is 1.5A continuous. Since the L91 is lower voltage, the continuous power is lower. The cell maximum current ratings are set to avoid overheating.

But Doug, many 123 lights spend a lot more than 1.5A. From Brocks site the N62 draws 3.7A. ???

Edit: I have also shorted a fresh cell for 5-10 secs without shutoff.

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AilSnail said:
But Doug, many 123 lights spend a lot more than 1.5A. From Brocks site the N62 draws 3.7A. ???

Edit: I have also shorted a fresh cell for 5-10 secs without shutoff.

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I would presume that the PTC is specified for well above the cell rated continuous. I have seen an intermittant rating of 3.5A for some 123s. Just like fuses, PTC overcurrent devices have a time/current/temperature characteristic. The higher the current and temperature, the shorter the trip time. For short periods they can carry current well above their continuous holding current. Just the other day I measured the trip characteristics of a li-ion cell rated at 1.2A max continuous drain. It's PTC took 3 seconds to trip at 15A.

thanks. the best deals i found for 3v AA's were CR3V and single cells at cheapbatterys.com .