Battery question -- Homemade battery not working

[K.Callaghan]

I was wondering if anyone could help me out here,
Ive built a simple battery, using two separate types of metal (copper and zinc). Using a voltage meter I can clearly see a stable reading of 1.5 volts when connecting to the anode and cathode, however when testing this on a small moter which runs fine using a standard 1.5 volt (AAA) energizer battery, my homade battery fails to achieve any result. I initially thought my voltage meter was faulty but it's not having seen the same readings on multiple devices.

Any ideas on why this may be?

 

[phyzguy]

While your homemade battery generates 1.5V, it is unlikely to have the capacity to generate a significant amount of current. It is the current through the motor windings that cause the motor to turn. Try measuring the voltage across the two batteries (the AAA and your homemade one) when they are connected to the motor. I suspect the AAA stays near 1.5V, while your homemade battery voltage drops to near zero when connected to the motor.

 

[K.Callaghan]

While your homemade battery generates 1.5V, it is unlikely to have the capacity to generate a significant amount of current. It is the current through the motor windings that cause the motor to turn. Try measuring the voltage across the two batteries (the AAA and your homemade one) when they are connected to the motor. I suspect the AAA stays near 1.5V, while your homemade battery voltage drops to near zero when connected to the motor.

Interesting. Any ideas why I'm loosing current? Perhaps material size or configuration? And your right because measuring from (aaa-negative) > (homemade-positive) connected in series results in a voltage of around 1.5. rather than 3 volts... So if it's a current issue what are my options in order to increase its magnitude ?

 

[AJK]

I'm not sure if your home made battery will be able to be modified to produce the current needed to power the motor. Batteries producing more current are made from different materials that allow them to produce much more current than a simple experimental battery often made from a lemon with a nickel and penny or similar is more just for educational purposes and testing. If it is a visual representation of the battery you are interested in let me suggest using something other then a motor. I bet it would light up a LED without a issue for a good bit of time.

 

[K.Callaghan]

I'm not sure if your home made battery will be able to be modified to produce the current needed to power the motor. Batteries producing more current are made from different materials that allow them to produce much more current than a simple experimental battery often made from a lemon with a nickel and penny or similar is more just for educational purposes and testing. If it is a visual representation of the battery you are interested in let me suggest using something other then a motor. I bet it would light up a LED without a issue for a good bit of time.

Hey AjK thanks for your reply aswell.
Yea it's more the "current" I'm after. I feel like a battery with no current is not really a practicle battery at all! so increasing current is priority #1. I can configer any number of arrangements of its layout to increase voltage yet current remains the same. Perhaps increasing acidity of the solution ? Would a larger hydrogen ion content have any effect on its current ?

 

[sophiecentaur]

There is a problem with simple cells and that is polarisation. Gas is formed on the plates and that reduces their effective area considerably and, hence, the current capability dies. This problem was dealt with by Leclanche, who invented the first(?) method of dealing with this problem.
I saw this effect when trying to get a simple school demo to work long term to drive a battery clock for an extended time. So you are in good company.
You could try using a much bigger area for the two plates (20cm square, perhaps).

 

[rootone]

You didn't mention what you are using as an electrolyte.
In car batteries this would be sulphuric acid, but there are other possibilities that might be better for your home made cell.

 

[K.Callaghan]

There is a problem with simple cells and that is polarisation. Gas is formed on the plates and that reduces their effective area considerably and, hence, the current capability dies. This problem was dealt with by Leclanche, who invented the first(?) method of dealing with this problem.
I saw this effect when trying to get a simple school demo to work long term to drive a battery clock for an extended time. So you are in good company.
You could try using a much bigger area for the two plates (20cm square, perhaps).

Hey sophie Awesome reply thank you !
Yes, this makes a lot of sense, I think my big issue is the polarization created during electrolysis. Larger materials are out of the question though :) I'm afraid weight is also a factor in this case.

 

[sophiecentaur]

Hey sophie Awesome reply thank you !
Yes, this makes a lot of sense, I think my big issue is the polarization created during electrolysis. Larger materials are out of the question though :) I'm afraid weight is also a factor in this case.

Battery technology has taken us far beyond the cell that you are using. We get to assume that we can use a power tool for an hour on one charge of a Lion battery. Big business and some very secret work involved.
Why not try a form of the leclanche cell, based on info in that wiki article?

 

[K.Callaghan]

Battery technology has taken us far beyond the cell that you are using. We get to assume that we can use a power tool for an hour on one charge of a Lion battery. Big business and some very secret work involved.
Why not try a form of the leclanche cell, based on info in that wiki article?

Yea I am definitely taking some notes, thanks for the link. Very helpful! And yes as far as the advancements in design I can imagine the secrecy, however when it comes down to the actual physicalweight of any standard single cell battery, even today the industry is barley able to stay above water pardon the pun. Ie... Battery's are heavy as hell based on current models. I believe that smaller open system cells are the future!

 

[K.Callaghan]

You didn't mention what you are using as an electrolyte.
In car batteries this would be sulphuric acid, but there are other possibilities that might be better for your home made cell.

Hey rootone ! It's a secret formula ;) haha it's alkaline in nature, non toxic.

 

[CWatters]

Yea I am definitely taking some notes, thanks for the link. Very helpful! And yes as far as the advancements in design I can imagine the secrecy, however when it comes down to the actual physicalweight of any standard single cell battery, even today the industry is barley able to stay above water pardon the pun. Ie... Battery's are heavy as hell based on current models. I believe that smaller open system cells are the future!

Battery companies have large research programs trying to improve battery technology. I believe it's quite easy to make batteries with higher capacity but the problem is you also need good battery life. Typically they try to increase capacity by increasing the surface area. One way to do that is by giving the electrodes a fine texture of some sort. However when you charge and discharge a cell you can get physical/dimensional changes that can damage the fine texture reducing cell capacity. Sometimes you find cycling the cell causes the growth of crystals that can puncture separators or otherwise short circuit a cell. So once you have invented a new high capacity cell your next job is to cycle it 1000 times and see if it is still as good.

PS You can get Li Cell that are essentially enclosed in a plastic bag - so there is very little excess weight.

 

[tech99]

A good battery can be made by using Copper Sulfate as the electrolyte and copper and zinc (or magnesium) electrodes. It will give about 1V and can operate small devices such as a low current motor and 3 batteries in series can light a flashlamp bulb.