Choosing batteries

Hi guys,

This is probably a very simple question, but I need some help to figure it out:

I have a few components that need to run on batteries:

Arduino Mini Pro (3.3V)
LSM9DS0 9DOF board (not sure, I think between 2.4 and 3.6 V)
Bluetooth mate (3.3 - 6 V)

This would basically be my circuit...I need to power it with as small a set of batteries as possible, I'm not sure though how those voltages work. Am I right that I could put some coin cell batteries in series?

Any help would be much appreciated!

Lester

Sounds like a single 3.3V supply would be simplest:

LiPo (nominally 3.7V) plus a low-dropout 3.3V regulator?

LiFePO4 battery (3.2V nominal) - regulator not required.

Other battery pack plus buck or boost DC-DC converter as appropriate?

Coin cells could be many things, lithium low current 3V, alkaline 1.5V. The
non-rechargable lithium coin cells cannot usually source enough current
for a project (2mA is a common spec for instance). Alkaline coin cells are
much more powerful but only 1.5V each.

Have you requirements for operating time? For maximum capacity in minimum size/weight
LiPo is the best, although there are safety issues to consider.

I happen to have sitting on the desk here a 240mAh LiPo cell that's 5.5g, 20x30mm in
size and 5mm thick... Don't expect much more energy density than that from a small
battery.
Do you know the total current consumption?

MarkT:
Sounds like a single 3.3V supply would be simplest:

LiPo (nominally 3.7V) plus a low-dropout 3.3V regulator?

LiFePO4 battery (3.2V nominal) - regulator not required.

Other battery pack plus buck or boost DC-DC converter as appropriate?

Coin cells could be many things, lithium low current 3V, alkaline 1.5V. The
non-rechargable lithium coin cells cannot usually source enough current
for a project (2mA is a common spec for instance). Alkaline coin cells are
much more powerful but only 1.5V each.

Have you requirements for operating time? For maximum capacity in minimum size/weight
LiPo is the best, although there are safety issues to consider.

I happen to have sitting on the desk here a 240mAh LiPo cell that's 5.5g, 20x30mm in
size and 5mm thick... Don't expect much more energy density than that from a small
battery.
Do you know the total current consumption?

I agree with all this. I like the idea of a DC to DC convert the best because it allows you to get the most out of your lithium battery. Look at this:

and you can get as small as 110mAh lithium batteries which are tiny!

MarkT:
Sounds like a single 3.3V supply would be simplest:

LiPo (nominally 3.7V) plus a low-dropout 3.3V regulator?

LiFePO4 battery (3.2V nominal) - regulator not required.

Other battery pack plus buck or boost DC-DC converter as appropriate?

Coin cells could be many things, lithium low current 3V, alkaline 1.5V. The
non-rechargable lithium coin cells cannot usually source enough current
for a project (2mA is a common spec for instance). Alkaline coin cells are
much more powerful but only 1.5V each.

Have you requirements for operating time? For maximum capacity in minimum size/weight
LiPo is the best, although there are safety issues to consider.

I happen to have sitting on the desk here a 240mAh LiPo cell that’s 5.5g, 20x30mm in
size and 5mm thick… Don’t expect much more energy density than that from a small
battery.
Do you know the total current consumption?

Thanks a lot for your input, Mark!

I am not sure I understand everything you say, but I will try and figure it out! :slight_smile:

I currently have 6x 3V Lithium coincells on my desk and a Li-ion 1000mAh, 3.7V battery

The operating time is not really of any concern…it’s a prototype that needs to run for a few hours, that’s enough at first…

No, I’m not sure about the current…I figure it should be on the spec sheets right? But I can’t really find it, I am not good at these things :-\

Charles_Creations:
I agree with all this. I like the idea of a DC to DC convert the best because it allows you to get the most out of your lithium battery. Look at this:

https://www.sparkfun.com/products/11231

and you can get as small as 110mAh lithium batteries which are tiny!

Thanks a lot Charles!

I will take a look at it!

Lester