From Canon:
Details
AA Lithium batteries cannot be used with any Speedlite or Macrolite products and compact battery packs including those listed below because certain AA lithium batteries, in rare cases, may become extremely hot during usage in such products.
Canon Products
Speedlite 220EX | Speedlite 580EX |
Speedlite 270EX | Speedlite 580EX II |
Speedlite 270EX II | Speedlite 600EX |
Speedlite 320EX | Speedlite 600EX-RT |
Speedlite 380EX | Macro Ring Lite MR-14EX |
Speedlite 420EX | Macro Ring Lite MR-14EX II |
Speedlite 430EX | Macro Twin Lite MT-24EX |
Speedlite 430EX II | Compact Battery Pack CP-E2 |
Speedlite 540EZ | Compact Battery Pack CP-E3 |
Speedlite 550EX | Compact Battery Pack CP-E4 |
Thank you,
Customer Support Operations
Canon U.S.A., Inc