there are different types of lithium batteries, and each have their own limits .. the type used in dive lights is the same thats used in computers and cellular phones and has a higher allowable limit than say som,ething like a liSOCl2
here is the pertinent regs
According to IATA, "
[FONT=Arial,Italic]consumer electronic devices containing lithium or lithium-ion cells or batteries, such as
watches, calculating machines, cameras, cellular phones, lap-top computers, camcorders, etc., when
carried by air passengers or crew for personal use"
are permitted aboard passenger aircraft as carry-on
baggage or checked baggage, without the approval of the operator or pilot-in-command.
The same applies to [FONT=Arial,Italic]spare batteries [/FONT]for these devices, as long as they are
- individually protected against short circuits,
- in carry-on baggage only,
- for primary batteries, with a lithium content of less than 2 grams,
- for lithium-ion batteries, with an "aggregate lithium-equivalent content*" of less than 8 grams,
If the aggregate lithium-equivalent content of lithium-ion batteries exceeds 8 g but not 25 g, the number of
spares is limited to 2 per person. Primary batteries containing more than 2 grams of lithium and
rechargeable batteries containing more than 25 equivalent grams of lithium-equivalent cannot be carried by
passengers aboard aircraft.
[/FONT]
ADDITIONAL INFO
a LI-on cell of about 7Ah has a lithium equivalent of abour 2 grams
