Power options

Would it be better to use a single cell lipo/liIon and boost it to the voltage I need, or would a high voltage bucked down to the voltage be good. So question is would a single cell get drained faster boosted or a 2~3 cell bucked drain quicker. FYI battery capacity will be identical in either situation

Hi,

I don't have an exact answer but it seems it would depend on the efficiency of your particular converter.

I would think the buck (down converter) would have an edge on efficiency due to the lower input currents.

It depends.
Look at the efficiency graphs on the Pololu website.

A single LiPo is easier to charge in-circuit.
Leo…

Buck is usually a bit more efficient, all else being equal - but the difference is small and the added complexity of charging multiple cells probably favors a 1S battery. If possible, try to skip the boost and run your project straight off the battery - that both improves the efficiency and saves you the quiescent current of the boost converter.

If you really mean battery CAPACITY (mAh) then two or three cells would have twice or three times the energy of a single cell so naturally they would last longer.

OTOH if you meant total energy (so 1S 300mAh vs 3S 100mAh) and you're talking about conversion efficiency I have no idea.

Stev

Squid90:
So question is would a single cell get drained faster boosted or a 2~3 cell bucked drain quicker. FYI battery capacity will be identical in either situation

If the power consumption is the same for both setup then a single cell will always drain faster than 2 or 3 cells (unless your buck converter is very crappy)

Convert your battery specs into mWhr + consider conversion efficiency and you’ll get the idea.

Example

Battery
1 cell = 3.7V*2600mAh = 9.6Whr
3 cell = 3.7V2600mAh3 = 28.8Whr
9.6Whr < 28.8Whr
Efficiency
Boost converter = 90% efficient
Buck converter = 90% efficient
Boost = 9.6Whr*90% = 8.6Whr
Buck = 28.8Whr*90% = 25.9Whr
So we get 8.6Whr < 25.9Whr

Now let’s say IF your buck converter is only 25% efficient, THEN
Buck = 28.8Whr*25% = 7.2Whr

So this time - boost 8.6Whr > 7.2Whr buck