Which battery technology to use?

[neazoi]

Hi I have a circuit (rf preamplifier) that can be powered from 0.8v to 5v.
Higher voltage is at benefit, to increase dynamic range.

I consider two batteries for it (it has to be a single cell at about the AAA diameter):
1. AAA 1.2v Ni-MH low self discharge.
2. 10440 Lithium ion battery 3.7v

Obviously 2 is better, however the li-ion cannot be discharged to less than 3v do avoid damaging.
I feel like I loose quite a lot of overhead voltage, since the circuit can operate down to 0.8v. So why switch it off at 3v?

Is there any other battery or solution I should consider to cover this overhead?

 

[BradtheRad]

the circuit can operate down to 0.8v.

I'm not sure I would drain a AAA nimh down to 0.8V. I think they prefer to operate between 1.0 and 1.4V. You can boost that to 5V if you wish, but it requires that you draw 5x as much current from the battery to accomplish that. The battery will drain much more quickly.

Since you specify a single battery, I think you would like to extend battery life. What supply V do you really need? Would it be sufficient if you were to boost 1.2V twice as much, to 2.4v?

 

[treez]

There might be some kind of Nicad that is ok going down to 0.8v or even less.
tHATS WHY NICADS GET USED IN EMERGENCY LIGHTING.
THEY MIGHT EVEN NOW BE ILLEGAL FOR ANYTHING ELSE DUE TO POISON IN THEM. (sorry about capitals)