How to change the batteries on Spykee, the robot.

Spykee came back to life when attached to a 12V portable battery.

In the video below, we hack into Spykee to attach new leads which will later allow for the connection of an external battery pack.  We also connect a multimeter to monitor the battery volage.  We connect a 12V battery, charged with a solar panel, for testing.  Yes, Spykee works on 12V and could be off-the-grid!

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Next, we connected a new external battery pack that uses standard AA rechargeable batteries.  Nothing proprietary here.  We made the new battery pack and now Spykee is better than new. His new external AA battery pack has a higher charge capacity than the original pack that came from the manufacturer.  The original pack was rated at 1,800 mAh while my new home-made replacement battery is rated at 2,400 mAh.  The batteries I chose are Imedion Low-Discharge AA batteries made by Powerex.  See how it works in the video below.

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Testing the Original Battery Pack

I tried freezing the original batteries that came with Spykee.  That improved the battery voltage, but was not enough of an improvement to get Spykee moving.

Spykee's original 9.6V NiMH battery

The video below shows the freezing process and how freezing increased the voltage of the batteries.

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Disassembly of the original Spykee battery pack

When I took the pack apart, I found 2 bad cells and 6 good cells.  The good cells could be used for another project.

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I put the two bad cells into my battery charger.  One of them charged up.  That leaves me with one cell at 0 Volts.  I plan to surge it with my solar panel.  Spykee’s original batteries will live on in another application.

From the summer of 2008 when I started to get serious about solar panels.

Peltier Cooler (also called TEC or Thermo Electric Cooler) - resting against a hot brick

Video of experiment…

The fuel for the fire was just fallen tree branches that I found on the ground.  The portable battery was charged up by a solar panel.

The Peltier cooler rested against one of the bricks.  The brick got up to 210 degrees F while the aluminum heat sink was about 70 degrees F.  At this temperature difference (140F), the Peltier cooler produced:

• 70mW
• 1.05V
• 67mA

The power generated by this Peltier cooler is comparable to the power generated by a small solar panel on a solar landscaping light.

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La Crosse WS-2316U Wireless Weather Station Review

12V adapter-splitter review

This adapter plugs into a single 12V battery outlet and splits it into three outlets.  Could be used to power three gadgets from your car or from wherever else you have a 12V outlet.  I have one in my house for off-the-grid backup power.

Video review…

This adapter allows you to power up three items from a single 12V source. In the video above, I powered up a cell phone, a bluetooth transmitter, and an Arduino circuit board.

Powering an Arduino board with a 12V battery

I bought this item from MPJA Online. I have ordered a few things from them now and am impressed with their fast shipping and cheap prices. Their price for this item is $6 plus shipping. (I am not being compensated in any way for this review. This post is just for information sharing.)

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Charging a Media Player with Solar

The video below shows three different electrolytes for a cell.  Which electrolyte will be the best, producing the most voltage and current?

To make your own cell as in the video, get a couple scrap pieces of metal like Copper and Zinc.  The Zinc can be in the form of Zinc-plated steel.

Dunk both metals into a conductive liquid.  This experiment will test three liquids.

1.  plain tap water

2.  water with Sodium bicarbonate, also known as baking soda, which is a salt

3.  water with Sodium Chloride, known as “table salt”

Which one will produce the most power?  Which one will produce the highest voltage and current?  See the video below to find out…

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Spoiler alert:  answer is below.

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Sodium bicarbonate dissolved in water produced the most voltage, current, and power.

tap water alone produced 0.62 V, 0.27 mA

water with sodium chloride produced 0.70 V, 0.50 mA

water with sodium bicarbonate produced 0.71 V, 1.45 mA

Related post:  Tomato Battery

Acid can release electricity from metal.  What is an easy-to-find source of acid?   Tomatoes!

The video above shows how an LED and a buzzer are powered by a tomato battery.  It’s just two different metals dipped into mashed tomatoes.  It even helps charge a AAA battery.

How does this work?

It’s a chemical reaction.  Take any two metals, separate them with a liquid that conducts electricity, and you have a battery.  Details are included below.

What kind of tomato is best?

Well, green tomatoes are more acidic then red, ripe ones.  So, no need to waste a good eating tomato.  If you grow your own tomatoes, you could pick one early, while still green, and use the acid from that in the battery.

Update on Tomato Battery – 4 Days Later

The video below shows how the Zinc plating was stripped off the metal by the tomato acids.  Also shown is how the LED still lights up, although with less intensity, four days after the tomato battery was constructed.

Video above shows how the AAA battery was charged from the tomato battery.  The AAA battery went up from 1318mV to 1330mV.  While not much, it shows that this small scale experiment could have a practical use.  The energy transferred from the tomato battery to the AAA battery could be used in any application that uses AAA batteries, like wireless headphones or an LED flashlight.

Is the AAA battery being overcharged?

The battery label says it is 1.2V.  If the tomato battery is charging it up to 1.33V, is that overcharging it?  My short answer is “no”.  See the video below for an explanation.

About a week after the tomato battery was constructed, mold was growing on the tomato mix and power production dropped to nearly nothing so I disbanded this experiment and cleaned up my mess.

What kind of acid is in tomatoes?

Tomatoes have a pH of about 4.1.  The lower the pH, the stronger the acid.  To give some perspective, here are the pH values of some other acids.

0.0 Hydrochloric acid

1.0 Gastric acid (in your tummy)

2.2 lemon juice

2.4 vinegar

4.1 tomatoes

5.8 potatoes  source

6.0 urine (Yeah, your urine can be acidic and would work as a weak battery electrolyte!  It is usually more acidic when you first wake up in the morning and turns more alkaline as the day progresses.  The more meat you eat, the more acidic your urine will be.  Vegetarians can have alkaline urine.)

7.0 water (considered to be neutral and not an acid)

From my reading, it appears there are many kinds of acid present in tomatoes:

• ascorbic acid
• chlorogenic acid source
• folic acid source
• p-coumaric acid
• chlorogenic acid source
• salicylic acid source
• malic acid source
• caffeic acid source

What is the chemical reaction in the tomato battery?

In the video above, the tomato battery is initially made with:

• Zinc
• Copper
• acid

The Zinc is the negative terminal, the anode.  The tomato’s acid liberates electrons from the Zinc.

Zn(s)  –> Zn2+(aq) + 2 e-

Solid Zinc releases a couple electrons, changing into Zinc ions, which allows it to dissolve into the electrolyte (the water / tomato acid mixture).

Copper is the positive terminal, the cathode.  The Copper atoms attract electrons more than do the Zinc (Zn) atoms.  The electrons that came off the Zinc get sucked into the Copper terminal.

How does the acid help?

An acid’s active ingredient is positively-charged Hydrogen. The acid releases Hydrogen ions (H+) that are reduced to Hydrogen gas (H2), which bubbles around the electrodes.  When I was recording the video above, I did witness bubbles forming around the Zinc plates.  As more bubbles coated the Zinc plates, the battery made less power.  This is because the Hydrogen bubbles prevented the electrolyte from making contact with the metal.  When I lifted the plates out of the electrolyte, the bubbles vanished into thin air, literally!  After returning the plates into the electrolyte, without the Hydrogen bubbles covering the Zinc, the battery gave more power.

By the way, if you could capture this Hydrogen gas, you could generate power from it, too!  Just make a Hydrogen fuel cell and you would get two power sources here.  But back to the battery…

As the current flows, more Zinc ions are dissolved into the tomato electrolyte.  The Zinc is gradually being eaten away.

What is the chemical reaction when salt is added to the electrolyte?

A tomato is actually not necessary, nor is any acid.   Any pair of metals separated by any liquid that conducts electricity will behave as a battery.  The liquid cannot be pure water and the metals must be different.

Most combinations of metals and liquids do not produce enough electrical power to be practical.  The chemical reactions are usually not strong and soon stop producing an electric current.

The first battery was invented in 1800.  In early batteries, someone often had to scrub the metal plates to remove hydrogen bubbles, oxides, and other foreign material to keep the batteries working.  You could still use a battery like this if you didn’t mind the maintenance.

Salt water can be the battery’s electrolyte.  This is called an “air battery”.  However, using an acid generates more power, a higher voltage, and higher current, because it liberates the electrons from both the anode and the cathode.  This means the metals, in this case Copper and Zinc, both get consumed.  In an air battery (or salt water battery), only one of the metals is consumed, resulting in less power generated but also with less materials consumed.

In the acid battery, the acid and both metals are used up.  In the salt water battery, only one of the metals is used up – the other metal and the salt is never consumed.

Related post:  Make Your Own Air Battery

Charging a Cub Cadet lawnmower 12V battery with a solar panel and Sunsei charge controller.

The lawnmower battery will die during the winter months and will not start the mower in the spring unless it is charged. Charging the battery on a beautiful winter day helps ensure the mower will start up this spring.

Click image below for video…