sdc100 wrote:Lithium batteries don't have higher voltages. They are rated at 1.5V, just like alkaline batteries (rechargeable NiMH batteries are only 1.2V). So yes, you can use Dollar Store Duracells. You can even use ordinary zinc batteries and heavy duty batteries.
Where Lithium, ALkalines, Heavy Duty and ordinary Zinc batteries differ is in mAh, or capacity. That determines how long the batteries last. The included lithium batteries are rated at 3000mAh, I believe, and it's pretty constant regardless of load. Alkaline batteries are usually 2800mAh, but diminishes quickly under heavy load. That's why they don't last long in digital cameras.
I have a very similair device that I use Sanyo Eneloop Hybrid NiMh rechargeables and they work just fine.
I was curious about your post and looked up the batteries included, they do indeed have a 3000mAh rating but that is in 'pulse' 2 seconds on, 8 seconds off cycles. This is great for camera flash. On a device like this where the phone is usually being charged on a 500mah USB port connected to a computer or even at 1000mAh on a USB3.0 'quick charge' port, I don't see it pulling much more than 2000mAh.Many hybrid recharables like the Eneloop will easily handle that. Even on a usb 'wall wart' charger I don't see these phones it pulling more than 2mAh, if even half that, during charge.
I could be totally wrong here, and would love more technical clarification, but the Eneloops I use seem to work fine on my AA portable phone charger, and they last quite a long time too.
P.S. I'd not use normal rechargeables, on the hybrid 'pre-charged' type which do not drain (very fast) just by sitting in the device.