If I separate the rechargeable batteries and not leave it inside the flashlight, does that make a difference? Also, do primaries or rechargeables matter
I think the crux of the issue is that nobody in the shipping industry is actually following the regulations at all. The only part that sunk in was "lithium = fire" and they likely just fabricate their own interpretation.
Lithium batteries are class 9 dangerous goods (ie: miscellaneous) according to IATA regulations.
Any lithium battery that has not passed UN safety tests is automatically considered hazardous and barred from air transport. They don't come out and say it, but they strongly infer that they're talking about generic and counterfeit Chinese batteries in that subsection.
Primary cells may contain no more than 1 g of lithium each, and no more than 2 g of lithium for a pack of cells. Rechargeble cells may store no more than 20 Wh of energy, or 100 Wh for a pack. The total shipment including packaging material may weigh no more than 35 Kg and all batteries or cells must be electrically isolated from each other. Under these limits, you need only attach a battery handling label. Otherwise they must be fully labeled and handled as hazardous.
(The 2 g limit for lithium does not refer to the entire shipment, apparently. I've met
many postal workers and some customs officials who believe that it does, so consider yourself warned)
The limits don't seem to take into account the relative safety of different chemistries or design at all. A docile 20 Wh LiFePO4 battery is considered more hazardous than a cheaply built 10 Wh LiCo battery.
If the batteries are safely contained in or packed with the equipment they are used in (eg: Dell shipping laptops), you don't need to declare them as dangerous goods or affix a hazard label.
I take that to mean the IATA believes that it's safer to ship some six-cell hotwire with CR123s installed than to ship the same six batteries secured in an SC2 spares carrier...
I'm convinced cocaine was involved in the drafting of these regulations.