Bounce a battery on its end to determine its charge ?? - Page 1
Forum section: electronics / general

author: Sionyn
author_rank: Frequent Contributor
timestamp: August 14, 2013, 07:40:26 pm
content: density possibly,diffrent brand may be the cause of it ?

author: smashedProton
author_rank: Frequent Contributor
timestamp: August 14, 2013, 07:45:00 pm
content: Well I have no idea what he is on about, but batteries do get lighter after they are used up. E=mc^2 and such. The mass difference is negligible for this though...

author: SeanB
author_rank: Super Contributor
timestamp: August 14, 2013, 07:57:10 pm
content: It does enable you to tell the difference between a good cell and a fake one though.......

author: Legit-Design
author_rank: Frequent Contributor
timestamp: August 14, 2013, 08:02:45 pm
content: Bad battery has already started the process of leaking it's internals out? This makes it push out the terminal and make it more springy?I would also like to see tests with the same kind of battery, one still new and the other one drained, preferably from same package. To make it more scientific buy a 8 pack of those and divide them up for serious testing.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 14, 2013, 09:55:24 pm
content: If a genuine effect, it could be a change in viscosity - a fluid that can move around inside will cause damping, and make it bounce less.

author: AlfBaz
author_rank: Super Contributor
timestamp: August 14, 2013, 10:29:07 pm
content: Maybe we can re-instate the phlogiston theory!!

author: EEVblog
author_rank: Unknown
timestamp: August 14, 2013, 11:27:59 pm
content: It was just ludicrous to try this experiment on two different brand batteries

author: Stonent
author_rank: Super Contributor
timestamp: August 14, 2013, 11:32:41 pm
content: CHARGE YOUR CELLPHONE WITH AN ORANGE!

author: EEVblog
author_rank: Unknown
timestamp: August 15, 2013, 01:41:21 am
content: I was going to go all scientific on this and do controlled discharges and controlled drops on different brands etc, but then thought I'd try it quickly to see if it's like the video. I figured there wouldn't be much in it, if anything, but it turns out it does work and the difference is as obvious as shown in the video.My next step after that was to try and do some vibrational response analysis of the batteries, but I don't have the proper gear for that any more.

author: Corporate666
author_rank: Unknown
timestamp: August 15, 2013, 02:22:37 am
content: The video is a joke guysYou can see it cuts away just before he drops the Energizer battery, so it's not a battery anymore... just something that looks like one.I think it's like the old "did you know that, statistically, if more than 2 of the lines on the palm of your hand intersect, it means you are in the top 5% in IQ?"then you laugh as all the people stare at their palms inquisitively

author: Guppzor
author_rank: Contributor
timestamp: August 15, 2013, 02:34:57 am
content: If this test does show that your battery is flat or low in charge, here is a quick and easy way to recharge it:

author: EEVblog
author_rank: Unknown
timestamp: August 15, 2013, 03:34:29 am
content: Quote from: Guppzor on August 15, 2013, 02:34:57 am

author: c4757p
author_rank: Super Contributor
timestamp: August 15, 2013, 03:39:45 am
content: Thank you for that.....

author: AlfBaz
author_rank: Super Contributor
timestamp: August 15, 2013, 04:13:54 am
content: Its not just one dumbass, there are credits at the end, it took a team!!... I better rethink my use of electrical tape

author: EEVblog
author_rank: Unknown
timestamp: August 15, 2013, 04:14:54 am
content: Quote from: Corporate666 on August 15, 2013, 02:22:37 amNo, it's real, I tried it, it works exactly as claimed.

author: TerraHertz
author_rank: Super Contributor
timestamp: August 15, 2013, 04:24:00 am
content: Quote from: Guppzor on August 15, 2013, 02:34:57 amHA ha ....I thought he must be serious, ie a nutter, till he said "It's called electrical tape because it conducts electricity."So really he's a joker with an advanced degree in keeping a straight face.Sending up all the lunatic 'tubers out there.

author: c4757p
author_rank: Super Contributor
timestamp: August 15, 2013, 04:29:01 am
content: Quote from: TerraHertz on August 15, 2013, 04:24:00 am"Don't you hate it when you go to use a flashlight, or a TOS phaser...."

author: mariush
author_rank: Super Contributor
timestamp: August 15, 2013, 04:41:10 am
content: Quote from: EEVblog on August 15, 2013, 01:41:21 amDave, I think you would have to do a sort of double blind test.You KNOW which one is dead subconsciously and you may let the battery drop slightly differently than the full battery... you need to go full mythbusters and build a robot to with a hand which would drop the battery from an exact height... in a box so it won't be affected by air conditioning airflow etc

author: Dajgoro
author_rank: Frequent Contributor
timestamp: August 15, 2013, 04:35:24 pm
content: I went to try the same thing with Camelion C size alkaline batteries that I use in my multimeter.I recently bough new ones of the same kind and replaced the dead ones.And I was surprised by the results! I got the exact opposite effect. The charged battery bounced, and the empty didn't??? What is going on here?

author: Kremmen
author_rank: Super Contributor
timestamp: August 15, 2013, 04:59:30 pm
content: Quote from: smashedProton on August 14, 2013, 07:45:00 pmErm.. surely these cells are not nuclear powered? If not, E=mc^2 does not apply as chemical reactions take place in the electron shells only. Reduction/oxidation - basically exchange of electrons in more or less complicated ways. Mass is not converted however.Offhand i would say that the cell weight cannot change as the total number of electrons should be constant - they just swap electrodes as the cell is used up. Closed circuit and all that...

author: Fraser
author_rank: Super Contributor
timestamp: August 15, 2013, 05:54:12 pm
content: Even if there is any validity to this drop test, I advise against such treatment of modern Alkaline cells. Even without abuse some brands have a habit of leaking and doing damage to equipment, even when not discharged. I personally have had a lot of problems with Duracell/Procell and no longer buy the brand.An alkaline battery is constructed with the positive terminal formed by the cells metal shell. The negative electrode is inserted from the bottom and secured in place using a crimping method. An insulating electrolyte seal is located between the negative contact and the positive shell.The manufacturer of Duracell (Gillette) admitted to me that excessive pressure on the bottom of the cell can lead to seal failure and leakage of electrolyte. This comment pertained specifically to use in D cell Maglite torches.If you start dropping a good cells negative end onto hard surfaces, do not be surprised if you cause the cell to leak at some point in its life due to seal failure. Dropping any form of cell or battery onto hard surfaces isn't a bright idea.

author: smashedProton
author_rank: Frequent Contributor
timestamp: August 15, 2013, 06:01:46 pm
content: Quote from: Kremmen on August 15, 2013, 04:59:30 pmNo, I disagree. The energy is mass inside the chemical bonds. AA batteries hold about 5kj of energy so we are only arguing about 55E-15 kg.

author: Legit-Design
author_rank: Frequent Contributor
timestamp: August 15, 2013, 06:02:58 pm
content: Kipkay says the cells start to formgas insidewhich makes it more springy. Sounds plausible.I think we need x-ray comparison of cells and more scientific testing.

author: SArepairman
author_rank: Frequent Contributor
timestamp: August 15, 2013, 06:30:23 pm
content: cut it open under water and observe for gas bubbles if you wanna see if its comrpessed gas

author: Fraser
author_rank: Super Contributor
timestamp: August 15, 2013, 06:45:01 pm
content: To see what is going on you need to analyse what distortion occurs in the flat negative contact upon impact with the surface. It may well be the case that the negative cap becomes more domed or flexible as the cell ages. Think of it like a drum skin.Have people tried dropping the cells on their positive nipple to see what happens ? That is a part of the sell and may not flex so easily when dropped.

author: Corporate666
author_rank: Unknown
timestamp: August 15, 2013, 07:01:05 pm
content: Quote from: EEVblog on August 15, 2013, 04:14:54 amColor me amazed!Or, maybe Dave is just in on this hoax?

author: SeanB
author_rank: Super Contributor
timestamp: August 15, 2013, 07:01:37 pm
content: They do form gas, but the manganese dioxide inside is a depolariser that recombines the gas to water in the electrolyte. Gas build up is only a problem with very fast discharge ( like into a short circuit) and not an issue in normal use, but the pressure does change with time, temperature and state of charge a little.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: August 15, 2013, 07:04:42 pm
content: Quote from: Aurora on August 15, 2013, 06:45:01 pmI just did a quick and dirty check with some AAA batteries I had. It doesn't matter which end hits the table, the discharged battery bounces more than the new battery. I'll try some more when I get home.

author: AG6QR
author_rank: Frequent Contributor
timestamp: August 15, 2013, 07:45:34 pm
content: E=mc^2 holds regardless of the type of process. Addany kindof energy to a body, and its inertial mass increases according to E=mc^2. It's just that, with ordinary chemical reactions, the change is so small that it's almost always lost deep in the noise. That c^2 term is huge.Here's Einstein's original paper:http://www.fourmilab.ch/etexts/einstein/E_mc2/www/If a body gives off the energy L in the form of radiation, its mass diminishes by L/c².The fact that the energy withdrawn from the body becomes energy of radiation evidently makes no difference,so that we are led to the more general conclusion thatThe mass of a body is a measure of its energy-content; if the energy changes by L, the mass changes in the same sense by L/9 × 10^20, the energy being measured in ergs, and the mass in grammes."We now use different units, and use the letter E instead of L, but the conclusion has held up to experiment very well.Quote from: Kremmen on August 15, 2013, 04:59:30 pmJust to be clear, though, as a practical matter, the mass and energy change due to E=mc^2 is so tiny that I'm sure it's absolutely NOT responsible for any observable effect in bouncing a battery. 2000 mAh at 1.5V works out to 1.2 * 10 ^-10 grams. A tenth of a nanogram. That's not responsible for any mechanical effect at a visible scale.

author: Spunky
author_rank: Regular Contributor
timestamp: August 15, 2013, 08:58:42 pm
content: This must be a change in the compressibility of the electrolyte. All fluids have some bounce, even water, so I don't find it surprising at all. It's a neat trick though. I'll use it sometime to amaze the guys at work.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: August 15, 2013, 10:01:30 pm
content: Quote from: Kremmen on August 15, 2013, 04:59:30 pmMass is converted in chemical reactions. An electron in a high energy state has a greater mass than an electron in a low energy state. But the difference is miniscule, compared to the mass lost in nuclear reactions, and the energy is correspondingly lower.Physics is weird.

author: Skimask
author_rank: Super Contributor
timestamp: August 16, 2013, 04:20:17 am
content: Tried the same thing here with D cells, two fresh, two dead, same brand (Duracell), roughly the same production date, all 4 at room temperature, etc.Don't have video, don't have a camera worth even trying to get video...but...dropped them from about 6 inches, repeatedly.The fresh ones landed with a deeper pitched thud, bounced but not much, and landed upright more often.The dead ones landed with a bit of a 'tink' sound, seemed to bounce high, and couldn't get the dead ones to land upright at all.I'll call it a good quick&dirty check...That's my 2 cents worth of highly unqualified, totally anecdotal, statistically deficient analysis.

author: BravoV
author_rank: Super Contributor
timestamp: August 16, 2013, 05:29:49 am
content: Even though there is a safety vent mechanism, is it possible that the built up pressure but still below the venting threshold at those used cell might bulge the battery's bottom tab abit that made it springy compared to fresh cell ?

author: Skimask
author_rank: Super Contributor
timestamp: August 16, 2013, 05:49:17 am
content: I just put a straight edge across the bottom of all those D cells.Didn't see any differences between all 4 of those cells, and no noticeable difference in the feel of the bottom tab (e.g. didn't sink in when pushed on with my finger), but, again, highly unscientific tests...

author: Kremmen
author_rank: Super Contributor
timestamp: August 16, 2013, 06:29:05 am
content: Quote from: smashedProton on August 15, 2013, 06:01:46 pmWell, you are of course correct. For all practical purposes (and most non-.practical as well) this can be safely ignored. The mass loss inside a nuclear reactor is absolutely miniscule compared to the total mass - even more so with any chemical reaction which is why i didn't think of that at all.So true in the strict sense but as you originally pointed out, negligible. My previous reply was in the spirit of a nuke reactor where the mass loss is at least detectable, although the power levels to produce that loss are of course multiple orders of magnitude higher than in a measly cell.Mass lost through energy extraction won't help to identify a spent cell. There may of course be other factors at play, causing loss of mass (or any other detectable change in the drop test) as the cell is exhausted. I think this whole idea is BS but let's see if a plausible mechanism surfaces.

author: Stonent
author_rank: Super Contributor
timestamp: August 16, 2013, 07:03:45 am
content: I'd be interested in seeing a battery on a scale for one hour with the leads connected to make sure the weight wasn't shifting, then turn on the load and monitor the weight until the battery goes flat.

author: Kremmen
author_rank: Super Contributor
timestamp: August 16, 2013, 07:16:27 am
content: Where are the mythbusters when you need them.

author: houdini
author_rank: Regular Contributor
timestamp: August 16, 2013, 08:41:51 am
content: Well the mass loss would be made even more pointless by the fact that battery actually have fairly large size tolerances, to the point that i got some Duracell that pushed the battery cover out of flush so i couldn't use my mouse

author: AlfBaz
author_rank: Super Contributor
timestamp: August 16, 2013, 11:04:51 am
content: I haven't given this a great deal of thought, but would the battery have to be heavier to bounce higher?The surface the battery is bouncing off hasn't changed so given a controlled drop the energy the battery hits the table with is 1/2mv^2Some of this is lost on impact and what isn't is reflected by causing the battery to bounce back up. Doesn't it follow that for the battery to bounce higher you need more energy and as v is fixed by acceleration due to gravity the only way to get more energy is to either increase mass or reduce losses in the impact. My bet is with mike on this one, its the latter the chemical composition of the battery has changed such that it absorbs less energy on impact

author: Fsck
author_rank: Super Contributor
timestamp: August 16, 2013, 11:18:05 am
content: Quote from: mikeselectricstuff on August 14, 2013, 09:55:24 pmthat's what I'd think too. it'd make an amusing lab if you could somehow get a decent sample size of identically specced cells.

author: EEVblog
author_rank: Unknown
timestamp: August 16, 2013, 11:50:56 am
content: Quote from: AlfBaz on August 16, 2013, 11:04:51 amNo.QuoteYes, you are correct. It's the changing dampening effect of *insert battery composition theory here* that is at play here.Try dropping a lead weight and a bouncy ball of the same weight and see which one bounces higher.It is fascinating to measure this stuff with proper accelerators attached at various angles and getting various spectrum plots.

author: AlfBaz
author_rank: Super Contributor
timestamp: August 16, 2013, 12:01:14 pm
content: Quote from: EEVblog on August 16, 2013, 11:50:56 amThat's the problem with your "no" assertion, in your example you are not dropping to similar objects of differing mass you are dropping 2 items with differing mass and hugely differing surface elasticity properties.If the lead weight's surface would deform and revert back with the same proportion as the bouncy ball the lead weight would bounce back up to the moon

author: Wytnucls
author_rank: Super Contributor
timestamp: August 16, 2013, 12:22:35 pm
content: Not the moon, original height at best. It is called conservation of energy. The difference in height would give mgh, energy dissipated as heat.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: August 16, 2013, 01:00:17 pm
content: Quote from: Wytnucls on August 16, 2013, 12:22:35 pmYep - nothing more than high school level physics.

author: Wytnucls
author_rank: Super Contributor
timestamp: August 16, 2013, 01:22:55 pm
content: Yes, so, in the case of the AA battery, if the bouncing effect is confirmed, it can only be due to a chemical change in the electrolyte, with the formation of elastic polymer chains or the production of a gas in the material.

author: FJV
author_rank: Regular Contributor
timestamp: August 16, 2013, 01:39:51 pm
content: I,m not gonna dent perfectly good batteries.For those interested they might determinde if mass changes are an explanation by making a pendulum of the battery and measure the oscilation.etc.....

author: Excavatoree
author_rank: Frequent Contributor
timestamp: August 16, 2013, 02:03:27 pm
content: Quote from: FJV on August 16, 2013, 01:39:51 pmThe AAA batteries I tested showed the difference in "bounce" by dropping them 20 mm or so. The AA batteries Dave dropped were not damaged. As someone earlier said, dropping them from longer distances would, but I believe that the effect can be tested without damage to the batteries.

author: G7PSK
author_rank: Super Contributor
timestamp: August 16, 2013, 02:46:57 pm
content: I think that the bounce is due to water loss, I have noticed that old dead batteries are considerably lighter than new ones and the only reasonable explanation that I can come up with is water vapour venting from the battery, but the bounce could also be due to changes in the consistency of the deoxidiser in the cells.

author: ptricks
author_rank: Frequent Contributor
timestamp: August 16, 2013, 09:53:12 pm
content: Does anyone have a scale sensitive enough to weigh the batteries between charge and discharged ? Also wonder if the pivot point has shifted on the cells if you balanced them on the longest side.Energizer says the makeup of the battery is:Graphite 2-6%Manganese Dioxide 30-45%Potassium Hydroxide 4-8%Zinc - 12-25%Water , paper, plastic 18-22%

author: ddavidebor
author_rank: Super Contributor
timestamp: August 16, 2013, 10:10:59 pm
content: Dave urgently change eevblog to cevblog!!!We need some chimical engineer here, the situation is pretty low!Where are this electrone gone???xD

author: Phroon
author_rank: Contributor
timestamp: August 17, 2013, 02:37:00 am
content: Quote from: EEVblog on August 16, 2013, 11:50:56 amAnd that's why they make Lead Acid batteries and not Bouncy Ball batteries.

author: smashedProton
author_rank: Frequent Contributor
timestamp: August 17, 2013, 03:07:03 am
content: Quote from: FJV on August 16, 2013, 01:39:51 pmIs your asshole really so tight that you wouldn't take a tiny tiny risk for your curiosity?

author: smashedProton
author_rank: Frequent Contributor
timestamp: August 17, 2013, 03:25:48 am
content: Quote from: ptricks on August 16, 2013, 09:53:12 pmThe chemical reaction of the alkaline battery is 2MnO2 +Zn ---> Mn2O3 + ZnOManganese(III) Oxide and zinc oxide are water soluble while Manganese(IV) oxide and zinc metal are not. I think this is the cause of the effect.