Run OpenBCI on LiPo battery

yj · December 2015

Hello David,

I asked myself the very similar question...

Theoreticaly Yes.

From the LP5907 data sheet : 7.4.2 Minimum Operating Input Voltage (VIN)

...

The output voltage is not regulated until VIN has reached at least the greater of 2.2 V or
(VOUT + VDO).

In our case (32b board) VOUT=3.3Volts and VDO (the dropout fig18 p9) increases linearly from 0 to 130mV when the load current goes from 0 to 250mA.

In the worst case VIN has just to be greater than 3.43Volts.

3.7 Volts lipo should work...

@wjcroft & @biomurph or @anybodyelse : Have you ever tried ?

Yannick.

qwer1304 · December 2015

Hi Yannick,

Thx for this.

It'd seem that 3.7V is TOO restrictive with LiPo discharging, wires, temperature, etc.

Is Vout really 3.3V? I thought it was 3V only.

Thx,

David

yj · December 2015

You make me doubt, David,

on http://docs.openbci.com/hardware/01-OpenBCI_Hardware#openbci-hardware-documentation-openbci-32bit-board-openbci-32bit-board-circuit-schematic

the +3V regulator outputs 3.3V.

3.7V is the voltage at the end of the discharge for an intensity between 0.1 and 0.05 of the A/h capacity (80%)

the OBCI Card current is low, the voltage drop in the wires 100mA x 0.1 ohm = 10mV... not too much...

A 2S lipo is good only if you want to heat yourself.

Yannick.

qwer1304 · December 2015

Thx Yannick.

I wan't thinking about 2S but rather about adding a booster like William does.

I don't like it too much because of the extra complexity and the noise it adds.

David

PS BTW, what is this graph of? I means - why the cutoff at 800 mAh?

yj · December 2015

Ah!!! Sorry David , I thought you wanted to not to use a booster...

This graph is the typical way the voltage of a 1000mAh Lipo, decreases with the capacity used. At 80% (800mAh used) any lipo shows this "cutoff" as you say.

Yannick.

wjcroft · December 2015

http://docs.openbci.com/headware/01-Ultracortex-Mark-III#ultracortex-mark-3-assembly-instructions-embed-openbci-into-the-ultracortex

The Ultracortex instructions use the single LiPo cell.

Be careful with the 2S configuration, the 3.3 voltage regulator on the original board run has a 6V max. New boards being shipped are higher and would have no problem.

My Powerboost makes no noise whatsoever.

biomurph · January 2016

@qwer1304

Yes

faturita · May 2016

Hey,

I do not want to fry my hard-to-get-board so, will it work with a Li-ion 850 mAh @ 3.7 V ?? The typical Sparkfun model https://www.sparkfun.com/products/341 ? My model is OpenBCI ChipKit 32 bits V3-32.

Thanks a lot guys.

wjcroft · May 2016

Yes.

See the "Embed OpenBCI into the Ultracortex" step,

http://docs.openbci.com/headware/01-Ultracortex-Mark-III-Nova#ultracortex-mark-iii-nova-supernova-assembly-instructions-embed-openbci-into-the-ultracortex

Run OpenBCI on LiPo battery

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