### Author Topic: EEVblog #508 - Can You Test Battery Charge By Dropping It?  (Read 22911 times)

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#### EEVblog

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« on: August 15, 2013, 09:15:55 am »
Can you determine the charge of an alkaline battery by simply dropping it and see how high it bounces?
A followup to the KipKay video

#### ddavidebor

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #1 on: August 15, 2013, 09:36:59 am »
Mmh morning video niceeee
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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #2 on: August 15, 2013, 10:47:15 am »
The result you get might be correct. However I am not convinced by the testing method. Dave - thanks for doing a video about battery bounce vs charge.

Areas that could be done better:
• Do a blind test where you have a group of batteries of unknown charges, drop batteries, rate the charge based on the drops then compare it with a multimeter / see if you can rank the charge based on the how they bounce, record it then compare it with the actual result.
• Drop the batteries in the same way from the same height. e.g. use a line to drop the batteries from. Preferably make a device do the dropping. In the video
• Show that a given battery normally bounces in a certain way.
« Last Edit: August 15, 2013, 10:50:36 am by adam1213 »

#### Citizen

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #3 on: August 15, 2013, 10:56:06 am »
OMG it is not  rocket science...

Charged batteries have more electrons=> more weight,
Empty battery=>less electrons=>less weight.

You can also spin batteries to check if they are charged:
If it is full with electrons, then the battery will not wobble, since the mass is distributed equally through he whole? battery.
In case it is discharged, then it will wobble, because the electrons will shift the mass center...

#### mikeselectricstuff

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #4 on: August 15, 2013, 11:01:14 am »
Why would anyone think this is about weight? Weight changes would not change the bounce.
It's clearly a damping effect due to the change in physical properties affecting the mobility of the stuff inside, which change how much mechanical energy it absorbs.
I bet if you opened them up you'd find the bouncy one less goopy than the other
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#### EEVblog

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #5 on: August 15, 2013, 11:03:52 am »
The result you get might be correct. However I am not convinced by the testing method.

I said it was deliberately a very quick unscientific test, just as a go/no-go to show if it's true or not, or marginal.
From the result it is almost certainly true. I was expecting it to be marginal, but it's a fairly big difference in bounce.
I dropped some other fully charged ones and it appears consistent, as you'd expect.
« Last Edit: August 15, 2013, 11:12:12 am by EEVblog »

#### dr.diesel

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #6 on: August 15, 2013, 11:05:53 am »
I bet if you opened them up you'd find the bouncy one less goopy than the other

Perhaps some of the same reason dead batteries are prone to leaking as well.

#### EEVblog

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #7 on: August 15, 2013, 11:08:53 am »
OMG it is not  rocket science...

Charged batteries have more electrons=> more weight,
Empty battery=>less electrons=>less weight.

To quote Doc Brown - "weight has nothing to do with this"
It is not the weight, it is a change in the dampening effect of the changed chemical reaction and hence composition in the battery, as I mentioned in the video.

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #8 on: August 15, 2013, 11:14:05 am »
Why would anyone think this is about weight? Weight changes would not change the bounce.

right, it is not weight directly. An discharged batt have (actually you cant "have" dark matter, you can only "bind" it) less dark matter (which is due changed potential and/or amount of electrons), so the influence of dark energy (on the gravitrons) is bit higher and the batt can bounce more/higher.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
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#### EEVblog

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #9 on: August 15, 2013, 11:16:27 am »
• Do a blind test where you have a group of batteries of unknown charges, drop batteries, rate the charge based on the drops then compare it with a multimeter
Using a multimeter to determine a batteries charge level is a very poor way to do it.

Quote
• Drop the batteries in the same way from the same height. e.g. use a line to drop the batteries from. Preferably make a device do the dropping. In the video

I will do that, but I need some bits and more time.

Quote
• Show that a given battery normally bounces in a certain way.

I can confirm fully charged batteries bounce to roughly the same height.

#### Citizen

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #10 on: August 15, 2013, 11:17:55 am »
Lol. i was joking:))
BTW a charged battery has as much electrons in it as a discharged one;)

#### EEVblog

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #11 on: August 15, 2013, 11:24:09 am »
KipKay's video is a complete ripoff of this one done a month ago:

#### Wytnucls

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #12 on: August 15, 2013, 11:32:16 am »
You could also carefully recharge the depleted battery and see if it stops bouncing.

#### Psi

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #13 on: August 15, 2013, 11:56:30 am »
It's probably to do with the reflected shockwave being somewhat absorbed vs propagated throughout the battery chemicals.

A better question is, if you do it repeatedly will the absorption/propagation rob a full battery of charge or recharge a flat battery.
« Last Edit: August 15, 2013, 11:58:46 am by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)

#### ddavidebor

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #14 on: August 15, 2013, 01:05:01 pm »
No
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#### Wytnucls

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #15 on: August 15, 2013, 02:00:58 pm »
When the battery discharges, hydrogen gas is formed, increasing the internal pressure in the battery. The spongy KOH electrolyte then acts as a spring at impact, with a higher recoil than in a charged battery.
With the aid of a micrometer, one may be able to measure a slight difference in battery overall length depending on charge condition.

#### lewis

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #16 on: August 15, 2013, 03:35:04 pm »
I will not be pushed, filed, stamped, indexed, briefed, debriefed or numbered.

#### LaurenceW

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #17 on: August 15, 2013, 04:29:45 pm »
My dad dropped the car battery from our old Austin Marina on his foot, once. That was flat, but I don't think it bounced that much. I did learn a new Anglo-Saxon expletive, however.
If you don't measure, you don't get.

#### KedasProbe

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #18 on: August 15, 2013, 06:25:33 pm »
Maybe you can drill into one at the top to let the gas out.
Not everything that counts can be measured. Not everything that can be measured counts.
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#### hammy

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #19 on: August 15, 2013, 08:36:47 pm »
... as I mentioned in the video.

Before the video you bounced the batteries and then you discharged the two who bounces better. Then you marked them black and made the video.
No need to fake the video. You sorted the batteries before.

#### Legit-Design

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #20 on: August 15, 2013, 08:39:01 pm »
... as I mentioned in the video.

Before the video you bounced the batteries and then you discharged the two who bounces better. Then you marked them black and made the video.
No need to fake the video. You sorted the batteries before.

For next video, someone needs to go to the store and get fresh pack of batteries and film it all on one go. From buying to testing to conclusions. Please get James Randi as your audience so there is no trickery. After that someone will determine that the people at the store were actors and it was all faked.
« Last Edit: August 15, 2013, 08:40:59 pm by Legit-Design »

#### IanB

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #21 on: August 15, 2013, 08:51:14 pm »
So is nobody going to mention that dropping batteries onto a hard surface is a really bad idea?

With NiMH you can certainly damage the internal construction and cause a permanent loss of capacity.

With alkaline batteries there is a danger you could weaken the seal and make the battery more prone to leakage.

With carbon-zinc batteries you could snap the positive carbon electrode and kill the battery.

A good rule for all batteries is to treat them gently and do not subject them to mechanical shocks.
I'm not an EE--what am I doing here?

#### firewalker

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #22 on: August 15, 2013, 09:46:49 pm »
Take two metal cylinders. Fill them with water. Freeze the one. Drop them.

Alexander.
Become a realist, stay a dreamer.

#### Psi

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #23 on: August 15, 2013, 10:06:57 pm »
No
You can't say that unless you've actually tested it.
« Last Edit: August 15, 2013, 10:08:35 pm by Psi »
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#### EEVblog

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #24 on: August 15, 2013, 11:14:09 pm »
Before the video you bounced the batteries and then you discharged the two who bounces better. Then you marked them black and made the video.
No need to fake the video. You sorted the batteries before.

I assume you are kidding, right?

#### Excavatoree

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #25 on: August 15, 2013, 11:19:37 pm »
So is nobody going to mention that dropping batteries onto a hard surface is a really bad idea?

With NiMH you can certainly damage the internal construction and cause a permanent loss of capacity.

With alkaline batteries there is a danger you could weaken the seal and make the battery more prone to leakage.

With carbon-zinc batteries you could snap the positive carbon electrode and kill the battery.

A good rule for all batteries is to treat them gently and do not subject them to mechanical shocks.

I'm not being a wise-ass here, I feel I have to say that because my comment may appear snarky, when I'm being sincere.  Is the small shock of dropping a battery (really a cell, but I won't go there) those few cm really a problem?  Aren't they subject to far worse treatment in packing and shipping, and in use in various devices?

#### PeteInTexas

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #26 on: August 16, 2013, 05:54:08 am »
Gives a whole new meaning to "dead cat bounce"

« Last Edit: August 16, 2013, 06:09:41 am by PeteInTexas »

#### PeteInTexas

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #27 on: August 16, 2013, 06:17:37 am »
OMG it is not  rocket science...

Charged batteries have more electrons=> more weight,
Empty battery=>less electrons=>less weight.

To quote Doc Brown - "weight has nothing to do with this"
It is not the weight, it is a change in the dampening effect of the changed chemical reaction and hence composition in the battery, as I mentioned in the video.

No, no you're both wrong.  Its the Earth's magnetic  field: no charge, no attraction to either pole to drag the bounce hence a higher bounce.  Full charge, greater attraction to opposite pole to drag the bounce hence a thud.
« Last Edit: August 16, 2013, 06:19:51 am by PeteInTexas »

#### IanB

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #28 on: August 16, 2013, 06:46:25 am »
I'm not being a wise-ass here, I feel I have to say that because my comment may appear snarky, when I'm being sincere.  Is the small shock of dropping a battery (really a cell, but I won't go there) those few cm really a problem?  Aren't they subject to far worse treatment in packing and shipping, and in use in various devices?

Sure, just dropping from a height of 5 cm or so as David showed won't cause much of a shock. But reading the subject line without context is alarming. I can state from experience that dropping a NiMH cell from desk height onto a hard floor is certainly able to damage it.

Lest anyone be tempted to increase the drop height to see a greater bounce, I caution against it. I know an alkaline cell is not an NiMH cell, but given that alkaline cells have a tendency to leak and ruin electronics it would be wise not to take chances.

About packing and shipping and abuse during transit, yes this is actually a concern, although hard to prove or quantify. Bad handling between factory and consumer is something that may increase the risk of leakage when the battery is in your hands.
I'm not an EE--what am I doing here?

#### 99tito99

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #29 on: August 16, 2013, 07:05:49 am »
Poke a hole in the discharged bat to relieve the pressure, then check the bounce.
Cheers, Mark

#### ddavidebor

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #30 on: August 16, 2013, 08:57:26 am »
No
You can't say that unless you've actually tested it.

If i've understand the question then is no. That kind of things just don't happen.
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#### nitro2k01

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #31 on: August 16, 2013, 09:36:11 am »
If i've understand the question then is no. That kind of things just don't happen.
What kind of thing just doesn't happen?

You do realize a chemical process happens while the power is consumed right? A fresh alkaline battery consists of zinc powder for the anode and manganese oxide (MnO2) for the cathode. When the battery is dry, the anode becomes ZnO and the cathode another manganese oxide (Mn2O3). It stands to reason that the final ZnO is no longer a powder, but mostly a big solid lump, which is much less shock absorbent. But don't take my word for it, you could actually open a fresh and a dry alkaline battery and investigate the consistency of the materials.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!

#### nitro2k01

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #32 on: August 16, 2013, 09:42:24 am »
Right, you were answering Psi's question in the post above the "no" post. Well, it might actually serve to discharge the battery quicker. How? By temporarily or permanently damaging the integrity of the separator between the anode and cathode and help the self discharge happen more quickly.
I don't see how mechanical impact could recharge the battery. Maaaybe if it rearranged the anode and cathode materials such that an unused part of the chemicals could be used. Even so, that effect would be negligible at best.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!

#### ddavidebor

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #33 on: August 16, 2013, 09:44:03 am »
If i've understand the question then is no. That kind of things just don't happen.
What kind of thing just doesn't happen?

You do realize a chemical process happens while the power is consumed right? A fresh alkaline battery consists of zinc powder for the anode and manganese oxide (MnO2) for the cathode. When the battery is dry, the anode becomes ZnO and the cathode another manganese oxide (Mn2O3). It stands to reason that the final ZnO is no longer a powder, but mostly a big solid lump, which is much less shock absorbent. But don't take my word for it, you could actually open a fresh and a dry alkaline battery and investigate the consistency of the materials.

Don't mind you word, but how on earth you're going to restore the electrons charge and reverse the reaction WHIT A BUMP???
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#### nitro2k01

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #34 on: August 16, 2013, 09:51:30 am »
That's not what I said! Consider the possibility that there's unused zinc powder near the center conductor, or MnO2 near the outer shell, ie in either case far away from the separator so the reaction can't happen optimally. Shake it around and magic happens. But like I said, this effect would be somewhere between non-existent and negligible. The whole point of the electrolyte is to provide good ion flow across the whole battery. But if the electrolyte was somehow dried up, it could theoretically have a small effect.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!

#### ddavidebor

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##### EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #35 on: August 16, 2013, 10:24:50 am »
Ahhhhhn ok
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#### Oracle

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #36 on: August 18, 2013, 11:30:52 am »
I'm just wondering if this method can be used only whit alkaline batteries or also whit lead acid ones.

#### jancumps

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #37 on: August 18, 2013, 12:01:04 pm »
fail

#### 555applelc

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #38 on: August 18, 2013, 01:52:26 pm »
i can't see the video???
because of i come from china???

#### dr.diesel

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #39 on: August 18, 2013, 02:02:18 pm »
i can't see the video???
because of i come from china???

#### kyndal

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #40 on: August 19, 2013, 08:14:04 am »
Before the video you bounced the batteries and then you discharged the two who bounces better. Then you marked them black and made the video.
No need to fake the video. You sorted the batteries before.

I assume you are kidding, right?

no.... this thing stinks to hell and high water like your NE555 discoveries.  etc..
fool me.. twice?  i lost count.. anyway  there is no trust left in this world...... ;o)

saving grace is that its nowhere near april.  so i have been bouncing batteries..
that being said..  your probably going to need to build that rig..
weigh some batteries.  poke a few holes ?

haha..

mythbusting monday?

/Kyndal

#### hammy

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #41 on: August 19, 2013, 09:06:31 am »
Before the video you bounced the batteries and then you discharged the two who bounces better. Then you marked them black and made the video.
No need to fake the video. You sorted the batteries before.

I assume you are kidding, right?

I watched the video, I don't believe it. But I also don't think you fooled us. It's time to buy some batteries ...
« Last Edit: August 19, 2013, 07:03:42 pm by hammy »

#### robrenz

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #42 on: August 19, 2013, 11:00:51 am »
Here is my GUESS. There is an anode rod that is connected to the negative cap of the battery that runs up through the anode powder.  With full charge it is more intimately connected to the anode powder and the anode powder is more rigid itself. A force on the negative cap will try to push the anode rod further into the anode powder causing shear forces at the cylindrical interface of the anode rod and the anode powder and compression forces at the tip of the anode rod. This will make the negative cap more rigid than if there where no anode rod or if the anode rod could move freely (no friction)in the anode powder.  So we have a diaphragm spring (negative cap) with a central post (anode rod) that acts as a frictional damper whose damping rate is affected by the mechanical changes in the anode powder caused by the chemical reactions that occur in discharging the battery. Therefore change in the bounce height.

EDIT:  The reason the test works somewhat better on a compliant (rubbery) surface is the edge of the negative cap is fairly rigid from its shape and a flat hard surface cannot deflect the diaphragm center into the battery if the diaphragm is flat to begin with.  The compliant surface also lessens the need for the battery to be perfectly vertical at impact to get deflection of the diaphragm.

Remember this is all speculation on my part.
« Last Edit: August 19, 2013, 11:12:31 am by robrenz »

#### IanB

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #43 on: August 19, 2013, 02:45:31 pm »
When alkaline batteries discharge the chemical reaction produces bubbles of gas (hydrogen) inside. The gas increases the internal pressure of the cell, blowing it up a bit like a bicycle tire. This gas pressure is also what forces liquid out through the seals when batteries leak.

There are chemicals in the cell designed to absorb the gas and turn it into water, but some gas bubbles are always going to remain, especially if the cell is fully discharged.

So the strongest possibility is that "bouncy cell" = "gassy cell".
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#### robrenz

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #44 on: August 19, 2013, 03:35:46 pm »
So we can determine that by drilling a small hole in the edge of a depleted cell to relieve the gas pressure and retest. If same bounce as fresh cell then pressure is it. If same bounce as before more mechanical.
« Last Edit: August 19, 2013, 03:56:50 pm by robrenz »

#### c4757p

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #45 on: August 19, 2013, 03:52:45 pm »
I'm not sure that would be a conclusive test, though. Before hydrogen production you have n solid mass + 0 gaseous mass. After, you have n - m solid mass + m gaseous mass, and after drilling a hole, you are only back to n - m solid mass and a lower density. Granted, m is very small, but couldn't the density change possibly make a difference?

As far as I'm concerned, the hydrogen production is plausible enough that I'm willing to take that as an explanation even without testing. As long as it's an established fact that hydrogen is a product of battery operation, which AFAIK it is, then pressurization of the canister seems an obvious result.
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#### robrenz

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #46 on: August 19, 2013, 04:01:40 pm »
I just vented several dead bouncy cells with a dremel disc on the positive end and no change in bounce. I don't think pressure is the predominant mechanism. I don't have time right now to do more scientific testing but I might do a video later including showing the spring rate of the negative terminal diaphragm on fresh and depleted cells both vented and unvented on the depleted ones.

#### KedasProbe

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #47 on: August 19, 2013, 04:50:17 pm »
in a Nickel-Cadmium battery you have a different pressure curve:
http://batteryuniversity.com/learn/article/charging_nickel_based_batteries
(should act the other way around)
Not everything that counts can be measured. Not everything that can be measured counts.
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#### KedasProbe

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #48 on: August 19, 2013, 05:02:17 pm »
I just vented several dead bouncy cells with a dremel disc on the positive end and no change in bounce.
You have to do that on the one that has a bounce.
(like reducing the pressure of the ball that bounces too much)
Not everything that counts can be measured. Not everything that can be measured counts.
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#### robrenz

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #49 on: August 19, 2013, 05:09:43 pm »
That is exactly what I did. the bouncy cells are the dead cells. There was no change or decrease in bounce when vented.

#### ciccio

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #50 on: August 19, 2013, 07:26:49 pm »
Well, I'm really astonished: tested more than 40 dead or very discharged batteries (all VARTA INDUSTRIAL) against 10 new, charges batteries: it works. Dead cells bumps and fall down, charged cell stand up.
It's time to find the free time to investigate.
Best regards

Ciccio

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #51 on: August 20, 2013, 02:51:34 am »

While I find the bounce test to be impractical I do know of one practical application for a similar kind of testing.

For a long time myself and several other engineers at work noticed that 9V batteries could easily be tested to see how good they are by squeezing the flat side of the battery between our fingers.  A fresh fully charged battery feels solid but a dead battery feels squishy, we could actually see the sides squeeze inward between our fingers.  One day we decided to cut one open and what we found was that the material inside had contracted away from the sides as it dried out leaving about .5mm of space going around the battery.  It would stand to reason that the same thing happens with the AA battery and the contracted material allows the end cap to flex inward and create a greater bounce.   It's funny how stuff that a few engineers played around with 20 years ago comes back up again.
The Optimist says the glass is half full, the Pessimist says its half empty, an engineer only see's a glass thatâ€™s twice as big as it needs to be!

#### rsjsouza

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #52 on: August 21, 2013, 06:17:18 pm »
Why would anyone think this is about weight? Weight changes would not change the bounce.
+1. Although there is a small change in mass given the decrease in energy (nice explanation here).

A fresh fully charged battery feels solid but a dead battery feels squishy, we could actually see the sides squeeze inward between our fingers.
I wonder if this is still valid if the 9V battery is comprised of six LR61 cells (or AAAA)... (wikipedia reference)
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#### PA4TIM

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #53 on: August 26, 2013, 01:33:31 pm »
Funny, I'm gonna try this.
But about a tear ago I did some testing on batteries. Nicad, nimh, lead batteries and normal akaline. I found out full batteries have an impedance that is  Real Ohms with a small inductive imaginair part. Empty but still good rechargable batteries have a higher (AC, 1 kHz ) Rs as full ones but still an imaginairy part close to pure Ohms. A bad battery however has a much bigger negative imaginair impedance part. It is capacitive. I tested this with a lot cells and the measurement is done with a GR1650 and a HP decade to zero the bridge. And checked measurement (not from all tested cells because it takes a lot of time) with a VNA

I made a page about it on my site.  The reason I did this test was because I was experimenting with a desulfator. That test is not done yet. The dead battery is still connected to a loader and desulfator (so over a year) and I plan to do some tests again on it if I find the time.

http://www.pa4tim.nl/?p=3550
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
www.schneiderelectronicsrepair.nl  repair of test and calibration equipment

#### dexters_lab

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #54 on: August 26, 2013, 08:40:59 pm »
yes but would the gas not be within pockets? i'm not sure if the gas would be distributed around the inside of the battery case ready to be released by drilling a hole.

"A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools." - Douglas Adams

#### EvilGeniusSkis

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #55 on: June 04, 2015, 02:42:54 am »
http://www.princeton.edu/main/news/archive/S42/72/95S25/index.xml?section=topstories
turns out none of us got it right; @robrenz was the only one on the right track.

#### HighVoltage

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #56 on: June 04, 2015, 06:54:38 pm »
http://www.princeton.edu/main/news/archive/S42/72/95S25/index.xml?section=topstories
turns out none of us got it right; @robrenz was the only one on the right track.
Very interesting article.
Thank you very much !
There are 3 kinds of people in this world, those who can count and those who can not.

#### EvilGeniusSkis

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #57 on: June 04, 2015, 09:55:21 pm »
http://www.princeton.edu/main/news/archive/S42/72/95S25/index.xml?section=topstories
turns out none of us got it right; @robrenz was the only one on the right track.
Very interesting article.
Thank you very much !
Your Welcome, I read the article and the immediately thought of putting it on here for everyone else to read.

#### ornea

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #58 on: August 21, 2015, 12:05:00 pm »
OMG it is not  rocket science...

Charged batteries have more electrons=> more weight,
Empty battery=>less electrons=>less weight.

You can also spin batteries to check if they are charged:
If it is full with electrons, then the battery will not wobble, since the mass is distributed equally through he whole? battery.
In case it is discharged, then it will wobble, because the electrons will shift the mass center...
I dont think electrons are lost.  The same net electrons flowing out the neg (pos) equal the net electrons flowing into the pos(neg).  The battery does work to push them around.

#### eilize

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #59 on: August 23, 2015, 07:37:45 am »
Quote
Charged batteries have more electrons=> more weight,
Empty battery=>less electrons=>less weight.

You can also spin batteries to check if they are charged:
If it is full with electrons, then the battery will not wobble, since the mass is distributed equally through he whole? battery.
In case it is discharged, then it will wobble, because the electrons will shift the mass center...

nice try  ^^

a corpse   in free fall gain a speed
that speed....don't depend of the weight
it depend of gravity (ok it change from heigh...you need a lot of difference to see something :p)
a cannonball and a  feather fall at the same speed in vacuum
so, it depend of  air resistance (no luck a empty and a full battery have the same form or there is not enough difference)

IF you see difference when you let fall 2 battery ,it's because you don't blet fall at the same moment or the don't let fall from the same angle

#### tree

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #60 on: August 28, 2015, 11:48:34 pm »
Question is...If I slip on the batteriser, will the battery bounce higher or lower?

#### amyk

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #61 on: August 29, 2015, 03:00:23 pm »
Question is...If I slip on the batteriser, will the battery bounce higher or lower?
Probably not at all, thus it can increase the charge in the battery and make it last longer.

#### Godzil

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #62 on: September 01, 2015, 10:29:15 pm »
Question is...If I slip on the batteriser, will the battery bounce higher or lower?

Don't do that! With the 800x more energy in your battery you may create a blackhole! That's what batteriser is, accumulating more energy in a small area, like a blackhole does!
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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#### Barny

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #63 on: September 02, 2015, 07:48:58 am »
Funfact:
If you try the bounce-test with a button cell, the bouncing effect is extreme.
If you use a small button cell out of an hearing aid, it bounce nearly to the same high if it hit a hard surface when its emty.

#### ez24

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #64 on: September 10, 2015, 08:20:14 pm »
http://www.princeton.edu/main/news/archive/S42/72/95S25/index.xml?section=topstories
turns out none of us got it right; @robrenz was the only one on the right track.

Who would have guessed that bouncing batteries gets to this level:

Support for the project was provided in part by the National Science Foundation, the U.S. Department of Energy and Brookhaven National Laboratory.
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166

#### apis

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #65 on: September 10, 2015, 10:29:14 pm »
Nice picture:
« Last Edit: December 02, 2018, 05:15:09 pm by apis »

#### vinicius.jlantunes

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #66 on: September 11, 2015, 01:20:55 pm »
Thanks ez24 for that link, very interesting!

#### ez24

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #67 on: September 11, 2015, 07:52:17 pm »
Thanks ez24 for that link, very interesting!

Thanks but it was not my link -- it came from EvilGeniusSkis

So I also say thanks to EvilGeniusSkis
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166

#### vinicius.jlantunes

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #68 on: September 11, 2015, 08:08:06 pm »
ooops, right, thank you both!

#### EvilGeniusSkis

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #69 on: September 28, 2015, 03:24:10 am »
Thanks ez24 for that link, very interesting!

Thanks but it was not my link -- it came from EvilGeniusSkis

So I also say thanks to EvilGeniusSkis

#### BrianHG

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##### Re: EEVblog #508 - Can You Test Battery Charge By Dropping It?
« Reply #70 on: December 02, 2018, 01:20:13 am »
Here is a really good side-by-side comparison of full and empty batteries, and why they bounce higher when they are empty:

__________
BrianHG.

Smf