Capacitors what is best

Using Arduino General Electronics
1

i have a project that will be run from a battery 3.7v 70mah rechargeable but i must have a min 3v going through to make the system work i have tried to find a small enough 4v+ battery rechargeable but i can't find one small enough .
so i'm thinking the 3.7v battery with a Capacitor now i've never used a Capacitor in my projects before so i need advice on how to use them as they all have different values that basically are confusing

the battery im using is here
RS Battery

im looking to order from here so could someone point me to the best type so i can order one please.
RS online

there in only one restriction it must be no higher than 10mm and keep the diameter as small as possible. but also allowing the system to run at a min 3v min

2

What are you going to do with the C?

Putting it across the battery will be of no benefit in holding the battery to 3v.

Weedpharma

3

3.7V is the "nominal" voltage for a LiPo; the charged voltage is 4.2V. At 3.7V it's only at about 1/4th of its capacity.

If your current draw is low enough there are plenty of low dropout regulators that will provide the 3V you need. Pololu.com also sells some pretty small switching regulator modules that you should take a look at.

4

ok thanks for that i was under the impression that a Capacitor did that ... sorry

so a low dropout regulator will help out on that will it??

its just so the board will get the most from the battery before it needs a charge

5

For example an LP2985 has a dropout voltage of .28V at 150ma current draw, or .007V at 1ma draw. For a switching regulator, the Pololu D24V5F3 has a similarly low dropout.

6

I would not recommend discharging a LiPo below 3.2 volts or you will probably reduce the life of the cell. 3.3 volts would be safer.