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Author Topic: Intercalated graphite carries a resting voltage without giving a charge.  (Read 9118 times)

kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #15 on: December 26, 2019, 01:45:10 PM »
A couple things you might keep track of is temp and humidity. It is socked in fog where I'm at so moisture in the air may have some effect.

kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #16 on: December 26, 2019, 01:50:17 PM »
I tried everything I could think of.

Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #17 on: December 26, 2019, 02:49:24 PM »
A couple things you might keep track of is temp and humidity. It is socked in fog where I'm at so moisture in the air may have some effect.
I have a barometer in the shed so that’s a very good test. Thanks. I should get some good transients of the next couple of days. It has felt more humid but I have not measured it. I should add though if I hit with a torch voltage will increase.

kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #18 on: December 26, 2019, 05:53:39 PM »
I had to find out for myself how much moisture content effects the measurements. These are the results from 3 runs. I started each run with saturated separator of salt solution. I then popped the separator in microwave in ten second intervals and recorded voltage of assembled cell.
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kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #19 on: December 26, 2019, 06:16:52 PM »
I just realized that I'm not taking into account the contact when the separator drys. It becomes rigid and wrinkled and is effecting the readings. I'll try to clamp it someway before taking measurements.

sm0ky2

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #20 on: December 26, 2019, 07:52:28 PM »
Smoky2, I can only guess that your suggestion to use graphite is to point out something I'm overlooking.


It was for Jimboot , to eliminate galvanism as a possible explanation.
it is standard battery practice to use inert electrodes.
this also prevents corrosion and extends the lifetime of the cell.


You can connect Al or Cu or any suitable conductor to a graphite rod
and not worry about erroneous readings.


Analog meters don’t usually cause the same problem that the DMM’s do.
Because internally they are built to respond to the circuit,
Where as a DMM alters the circuit then analyzes the results.


Also DMM’s can be susceptible to static charges and be inaccurate at times.
(sometimes shorting the terminals or removing the battery can ‘fix them’)




On the uneven paper electrode surface:: the paper towel might not be the best way to go.
You may need coffee filter or something that will stay flat


kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #21 on: December 26, 2019, 08:01:40 PM »
Thanks for the info, I have a roll of celgard 2400 seperator material on order. What I need badly is some ideas for a non aqueous electrolyte that would be suitable for aluminum ion battery.

kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #22 on: December 26, 2019, 08:12:57 PM »
I will repeat the test tomorrow using filter as you suggested. I'm on night shift so I'm getting a little cross eyed from no sleep.

Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #23 on: December 27, 2019, 05:54:23 AM »
At 65% humidity 1.125 at 60% 1.140 . Btw this started at 300mv . I surprised it's risen over time. My analogue meter is busted but that will be a good test.

Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #24 on: December 27, 2019, 06:03:55 AM »
Also these are screen shots I took on the 21st. I'm using the house ground which is adding by the looks of it a harmonic set of spikes. The zoom is of the final spike in the sequence.[/size]

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kajunbee

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #25 on: December 27, 2019, 07:04:13 AM »
What I noticed in my test was the voltage was lower when I first formed the cell. After the first 10 second warming period the voltage increased. Now I'm not sure which way I should look at this. Did the warming lower its ionic resistance. Or did removing some of the water raise the salt concentration which lowered the resistance. Or a combination of the two. https://en.m.wikipedia.org/wiki/Aluminium–air_battery

Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #26 on: December 28, 2019, 02:01:01 AM »
Still at 1.18 this morning I built it two weeks ago.  I think I need to go and buy an analogue meter. It will be interesting to see the effect as when I remove the dmm the voltage rises.

sm0ky2

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #27 on: December 28, 2019, 02:28:03 AM »
Earth ground will always introduce those low-amplitude feedback signals
Partially telluric currents, partially underground television cables
(and yes with an Amp and filters you can watch tv from an earth battery signal)


But, 0 will always be 0 unless your other reference is a different part of earth.


With an ungrounded scope, 0 is the scope case, and what you are measuring could
be at any potential until you try to measure it.
At which point it is referenced to the scope.
Why does this matter?
Normally it doesn’t.
The scope shielded case has a high inductance.
but if it’s sitting on a metal desk and the cooling fan is blowing charged air onto it
the scope takes on a charge (and the desk oppositely)
Which makes 0 not 0.
(in which case everything would take on a voltage when you try to measure it)


There are many ways in which we can measure a potential.
When my PC is on, my desk measures +4.3v  with respect to earth fairly consistently.
(fatal flaw in electronics, ground everything to the case but the PSU to earth)


Once you eliminate every other possibility, and are still unable to discharge the material
Feel free to classify it as
an Electret
Category: 1n










Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #28 on: December 28, 2019, 06:17:04 AM »
.

Jimboot

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Re: Intercalated graphite carries a resting voltage without giving a charge.
« Reply #29 on: December 28, 2019, 06:20:23 AM »
Thanks Smoky.

I bought a passive analogue meter. Over the 3k resistor I get around 100mv. Leaves me scratching my head.
Every time I measure seems to get less and less so what ever it is looks like I'm dissipating heat?