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Using Lithium-Ion Rechargeable Batteries in my Garmin GPS
When determining which batteries will suit your application best1 it is important to note, if Lithium batteries are chosen, that two distinct types exist.
AA Lithium Batteries (recommended)
Voltage of 1.75V and are not rechargeable
Lithium-Ion (Li-ion) Batteries (not recommended)
NOTE: These are different from the lithium-ion rechargeable battery packs that come standard with some Garmin devices, such as Montana® handhelds.
Same physical size as AA batteries
Voltage of 4.2V and are rechargeable
It is not recommended that Lithium-Ion batteries be used. In many cases, these batteries exceed the limits of Garmin GPS devices and can cause irreversible damage. Check to ensure that the voltage listed on the battery does not exceed the voltage requirement of your GPS listed in your owner's manual.
1 The eTrex® Solar outdoor handheld contains an internal lithium-ion battery that is not user-replaceable.