This is great. I have used one LiFePO4 batteries (3.2 V) and a copper rod to replace two 1.5v batteries in a few electronic. This would be even better then a copper rod.
Search for "lifepo4 14500" It does need a specific charger. I bought my charger from batteryspace.com. I found the following linked from their site.
Charging Non-cobalt-blended Li-ion
While the traditional lithium-ion has a nominal cell voltage of 3.60V, Li-phosphate (LiFePO) makes an exception with a nominal cell voltage of 3.20V and charging to 3.65V. Relatively new is the Li-titanate (LTO) with a nominal cell voltage of 2.40V and charging to 2.85V. (See BU-205: Types of Lithium-ion.)
Chargers for these non-cobalt-based Li-ions are not compatible with regular 3.60-volt Li-ion. Provision must be made to identify the systems and provide the correct voltage charging. A 3.60-volt lithium battery in a charger designed for Li-phosphate would not receive sufficient charge; a Li-phosphate in a regular charger would cause overcharge.
