The KL3 can be run cheaply in a9P. Put a partially run down 123 in the front and a fresh alkaline AA in the back separated by a 17mm dummy. (Klaus built a bunch of these dummies for me.
) Go ahead and exhaust the 123. The KL3, unlike the KL1, has no step-up inverter. Thus, full brightness depends upon battery input voltage at or above the LS Vf. A fresh alkaline will take a while to drop to 1.2 V at the roughly 450 mA the KL3 probably draws when the battery voltage drops to just above Vf.
(RayoVac's spec sheet shows that an alkaline AA will run at 308 mA for 1.9 hours before it drops to 1.2V. The curve is pretty steep, so I'd extrapolate that it will probably stay above 1.2 V for around 0.5 hours at 450 mA to outperform NiMH for this period.)
Yes, I know. Mixing battery chemistries can create problems, so one needs to plan carefully. The battery chemistry with the least resistance (lithium in this case) should be placed closest to the positive end. This is so that the lower resistance cells won't try to charge the higher resistance cells. (Lithiums and alkalines don't like to be charged.
)
(If I used an AA NiMH instead of an alkaline I would have placed the NiMH in front of the lithium.)
When 3 @ 123's are bled down this way I'll try to polish them off together in the 9P and see if it finishes the 123's more effectively than my X5. Given the regulation of the KL3, I suspect it will be more gratifying using the 123's with the KL3 until it hits the steep decline slope than watching the X5 get progressively dimmer.
I also suspect that using two fair 123's with an almost dead 123 will get almost all remaining juice out of the almost dead 123.
Do very low 123's ever leak the way alkalines do? I've never seen one leak.
