Author Topic: Seawater Aluminum / Air battery.  (Read 41 times)

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Offline CG

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Seawater Aluminum / Air battery.
« on: October 15, 2019, 03:57:10 pm »
I decided to spend some time tinkering with batteries.
This battery is called an aluminum / air battery.
It is a primary cell (cannot be recharged), but can be renewed.
It uses aluminum as the fuel for the battery, it is consumed in the process of discharge.
It uses saltwater or seawater as the electrolyte.
The one I built uses commonly available materials, (one of my basic requirements.)
Basically;
An Aluminum soda can with the coating sanded off.
salt
water
paper towel
the carbon fiber wrap from a used home water filter.
(When removed from the filter it is a 10x24 inch sheet of fabric).
https://drive.google.com/file/d/1GqBw_IhZh81TYnNd4ImDxQKBVQ52FwI-/view?usp=drivesdk
Here's what wikipedeia says about it.
https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery

I built a small one to test it out.
It is about 1.25 inches square and about 0.187 inches thick per cell.

Here is the diagram;
https://drive.google.com/file/d/1GpqhOmGNLz4Wtb2EzsN3S4Oy1zeSrHR8/view?usp=drivesdk

I dissolved salt in water until no more would dissolve.
I measure about 0.5 volts for the 1.25" sq. cell.
To renew (recharge the cell) you just put in a new piece of aluminum (soda can with the inside sanded clean of the coating), and refresh the seawater.
To get higher voltages just add more cells in series. To increase the current you make the aluminum and carbon bigger, or add smaller  cells in parallel.
It has unlimited shelf life if you don't add the seawater. That way it can be ready in an emergency.
I'll keep tinkering with it.
P.S. Lots of seawater in Barbados.   ;D

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Offline CG

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Re: Seawater Aluminum / Air battery.
« Reply #1 on: October 15, 2019, 03:58:55 pm »
Delivers about 5-10 mA but voltage drops when the ammeter is connected.

Offline CG

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Re: Seawater Aluminum / Air battery.
« Reply #2 on: October 17, 2019, 12:56:53 pm »
I replaced the Stainless steel with Graphite and got a voltage boost to 1.0 volts per cell. Now it's just :  Aluminum , paper separator, Graphite with saltwater electrolyte.

https://drive.google.com/file/d/1HWo48G8GSmkt8y6DEExZGL4b1rS_HeJY/view?usp=drivesdk
« Last Edit: October 17, 2019, 02:27:21 pm by CG »

Offline CG

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Re: Seawater Aluminum / Air battery.
« Reply #3 on: October 18, 2019, 03:43:21 pm »
I also replaced the graphite pencil lead with the carbon rod from a heavy duty D cell. The voltage was 0.3 volts less.