Sure if you’re starting from scratch a li-ion setup makes more sense. But he already has the 500 primaries and he wants to use them. So he may as well have some fun. Easy enough to carry a second light in the event the first dies.
As for the amount of charge 123, this is interesting, I used 2 pcs recently, I found it in the drawer of the table, now I remember that I received them in 2018 with the old SF, the expiration date is 2015, the voltage before use is 2.9 volts. They worked on HDS and discharged to 2.4 volts. I put them aside, now I look, they have 2.7 V again. When I put them back in the HDS, they work for a while and die again. I put them in G2 with an M61LL head - work great.
For the last 33 years, I see that long-term planning is a rather ungrateful thing, but sometimes it works. If have 500 batteries and follow all safety rules - the current is not more than 1.5 A, use before the expiration of 10 years, use only in unicellular flashlights, etc. Then can make something like a plan for their destruction:
1) Determine their expiration date, before which everything must be destroyed. In order not to create a bunch of small boxes with dates, can choose the number by the closest expiration date. If they were all used once during a short period of research on a boat, perhaps all of them are from the same box. For example, choose a date after 7 years.
2) 500 / 7 / 12 = 5.95, i.e. 6 batteries per month must be destroyed.
3) Depending on the number of lights, their power and frequency of use, these 6 batteries can be destroyed both within a month and during the day if a person is often forced to work in the dark, therefore, can make adjustments to the plan. People’s preferences or lifestyle are also changing, so new adjustments are inevitable.
In view of all this and what people said from above, 1 pc battery vampire is required, everything else is at the discretion.
I had 1 Peak LED solutions, I did not like - QTC material was quickly destroyed, sent the wrong shade of the diode, poor assembly - lack of sealing of head, did not receive a response or help from the manufacture, although ordered directly.
With that many cells you need a very inefficient light lol yep go with a 6P and some good old P60’s or lumens factory has incandescent‘s for it.Also with a duel cell setup like that you can let all of us know if you have ANY issues with them.
I would sell/trade a bunch of them to get things that use the batteries myself as less and less people are using them and as people find out that rechargeables save money and when you top them off you have guaranteed runtime vs somewhat unknown runtime on a primary battery once you start using it often it is hard to calculate how much time is left on the partially used cell. One thing that a CR123 can be used for it replacing 2 alkaline cells in series in things to eliminate leak chances. If a flashlight uses 2AAs you may be able to hollow it out a little more and add some springs and use a 123 in it.