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I'm trying to experiment with supplementing battery power using microbial fuel cells. MFCs are batteries that produce their charge from decaying matter, but they often only get up to 0.9v (unless youre an electrical wizard, in which they can go to 6v). I have an Arduino, while it is off Id like to switch to charging the battery with this MFC. The issue is its going to be low amp (I havent measure it yet) and around 0.9v. Will charging it this low even do anything? Assuming the battery charge will be higher than the MFC.

I additionally thought maybe 3 or 4 in series could solve the problem, but one is the ideal scenario. If its not possible would anyone recommend using a supercap to relay the MFC charge instead?

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  • \$\begingroup\$ TI do a good range of 'power harvesters' that take low voltage, low current sources, and charge cells. Other manufacturers do similar ICs. \$\endgroup\$ – Neil_UK Jan 29 at 16:01
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I have an Arduino

If you want low power, this isn't the best choice, as it contains lots of circuitry that you might not use but it will still draw power. So if you want to supply it from a low power microial fuel cell, make sure you check how much current each part on the board uses.

The issue is its going to be low amp (I havent measure it yet) and around 0.9v.

Would be a good idea to measure it...

Will charging it this low even do anything? Assuming the battery charge will be higher than the MFC.

Nope.

A LiIon battery is probably the best choice here due to high charging efficiency. Also it has no "memory effect" so it can be charged when power is available, and its voltage range is ideal for most microcontrollers.

However you need to boost the voltage from your 0.9V fuel cell to charge the battery.

would anyone recommend using a supercap to relay the MFC charge instead?

a supercap won't boost your voltage

Check energy harvesting chips, for example from analog/LT. Here's one that looks interesting.

Even if you don't use it, reading the datasheet and app notes should provide useful information about what you want to do.

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