Inside a bad 9v battery. - Page 1
Forum section: electronics / general

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 06:06:14 am
content: So, I found a 9v battery, unsure of how old it is, it's a Panasonic one, still putting out 9 volts, but it could only put out 50ma, instead of the usual ~500ma, so I opened it up...All I can say is... eww, definitely does not look good lol.

author: Psi
author_rank: Super Contributor
timestamp: May 14, 2014, 06:07:57 am
content: It's normal for some 9volts to be potted like that.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 06:18:59 am
content: Quote from: Psi on May 14, 2014, 06:07:57 amIt's not potted, that's just the standard pile construction, but the brown stuff is supposed to be more of a white color.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2014, 06:35:52 am
content: Nothing about the symptoms or the appearance that suggest it is anything but used up.If you don't know what a "good" battery looks like inside, how can you say "it doesn't look good"?That particular example appears to be made from six recctangular 1.5V cells stacked up.Other 9V batteries are made up of six "AAA" batteries bundled together.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 06:54:24 am
content: Quote from: Richard Crowley on May 14, 2014, 06:35:52 amI have taken apart plenty of 9 volt batteries, and I have never seen one with the pile construction that looks like this, even when they are used up with barely any voltage.Also considering that it is outputting 9v but a 10th of it's normal current I would definitely say it has gone bad.

author: G7PSK
author_rank: Super Contributor
timestamp: May 14, 2014, 07:52:04 am
content: That is the old pile construction, been around since the late 1930's. The outer of each cell or pile is brown paper with a waxy substance over it, if you pull a new one apart it looks the same.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 14, 2014, 08:18:21 am
content: I remember,as a kid,that Eveready in Australia made a huge fuss about going over to the "pile" construction,bragging that it increased energy storage by a substantial amount compared to stacked cylindrical cells.Previous to that time,all the locally made "A" & "B" batteries for valve radios used cylindrical cells.Eveready got a bit of a jump on their competitor,Diamond,who took a while to change their factory procedures over.I always assumed from then that dry cell batteries were all of the slab tyoe,but recently,I've come across quite a few of the stacked cylinder type.

author: electr_peter
author_rank: Unknown
timestamp: May 14, 2014, 08:48:36 am
content: Quote from: Richard Crowley on May 14, 2014, 06:35:52 amSlight correction - 9V batteries can be made from six AAAA (4 A's), not from six AAA (thee A's). AAAA size is smaller than AAA.I have seen at least 2-3 different construction methods for 9V batteries. Stacked construction (as in forst post), six AAAA's. I think there may few other methods of stacking.Nothing unusual here.

author: mariush
author_rank: Super Contributor
timestamp: May 14, 2014, 08:54:32 am
content: Quote from: XOIIO on May 14, 2014, 06:06:14 amI don't know what makes you think a 9v battery is supposed to give you 500mA ... have a look at some datasheets and some discharge graphs:http://data.energizer.com/PDFs/EN22.pdfhttp://www.panasonic.com/industrial/includes/pdf/9V_Ind_Alka_Bat_Data_Sheet.pdfhttp://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_6LF22_US_CT.pdfhttp://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_6LR61_US_CT.pdfEven at 100mA, you'll only going to get about 3-4 hours of life out of the battery at that load.

author: saturation
author_rank: Super Contributor
timestamp: May 14, 2014, 02:53:32 pm
content: http://en.wikipedia.org/wiki/Nine-volt_batterydetails and photos for old style pile construction and multiple cells.

author: Legit-Design
author_rank: Frequent Contributor
timestamp: May 14, 2014, 03:46:45 pm
content: Dave already did a video about these:https://www.eevblog.com/forum/blog/eevblog-518-9v-alkaline-battery-construction/

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 03:48:43 pm
content: Quote from: Legit-Design on May 14, 2014, 03:46:45 pmYeah, see that's how these ones usually look too, I've never seen one with paper underneath the plastic, and digging into it I'm pretty sure it is not paper.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2014, 06:01:54 pm
content: Quote from: XOIIO on May 14, 2014, 06:54:24 amThen you haven't taken apart enough 9V batteries to be aware of the wide variety of constructions.QuoteYou aren't actually proposing that the internal appearance of the battery can be used as any reliable indication of good/flat/bad?It has never been my experience that you could diagnose ANYTHING from the internal appearance.(Of course physical trauma, crushing, puncturing, etc. and thermal meltdown are obvious upon inspection.)QuoteSome battery chemistries will still show the rated voltage OPEN CIRCUIT (i.e. with no load, as when using a high-impedance DMM) even when "depleted".Assuming that the battery is "bad" just because the open-circuit voltage is 9V is rather short-sighted, IME.

author: SeanB
author_rank: Super Contributor
timestamp: May 14, 2014, 06:40:01 pm
content: Normally with the pile contruction you have the outer plastic shrink, and inside that a wax dip over the cells. Then you have the cells, made from a paper outer wrap covering an inside mix. Top of the cell is a zinc sheet with a carbon coat on the one side, then a layer of manganese dioxide mixed with ammonium chloride to make a nearly dry paste, and topped with a graphite powder block. they are layered then pressed into a block in a die to get the cells to ontact, then wax dipped for protection from drying out, then sealed with a plastic shrink and then placed into a case. The contacts on one side are just a set of teeth onto the zinc plate and the other side a steel strip with teeth onto a zinc plate with the carbon contacting the carbon anode of the bottom cell. Simple to make, and as it is mostly dry you have little issue with it leaking.the cylindrical AAAA cells have 2 methods I have seen, either a set of tabs welded to top and bottom of each cell to interconnect, or more commonly these days a simple pressure connection with a silicone pressure plate and a plastic sheet with contact strips on it to join the cells.

author: scientist
author_rank: Frequent Contributor
timestamp: May 14, 2014, 07:58:23 pm
content: Quote from: Richard Crowley on May 14, 2014, 06:35:52 am*AAAA

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 07:59:56 pm
content: Another battery related question, what is the largest cr type battery? I found a cr 3032 for the clock in an old MacBook, do they get any bigger?

author: scientist
author_rank: Frequent Contributor
timestamp: May 14, 2014, 08:02:31 pm
content: Quote from: XOIIO on May 14, 2014, 07:59:56 pmThat's what she said.http://lmgtfy.com/?q=cr+battery+size+chart

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 08:56:26 pm
content: Guess the only larger one is CR11108

author: electrolux
author_rank: Regular Contributor
timestamp: May 15, 2014, 12:02:43 pm
content: That seems pretty standard to me

author: electrolux
author_rank: Regular Contributor
timestamp: May 15, 2014, 12:06:47 pm
content: Quote from: XOIIO on May 14, 2014, 08:56:26 pmVery odd I dint know they existed but there you go Learn something ne w from the EEVblog every time!

author: electrolux
author_rank: Regular Contributor
timestamp: May 15, 2014, 12:09:03 pm
content: There is a list of battery sizes On Wikihttp://en.wikipedia.org/wiki/List_of_battery_sizes.

author: miguelvp
author_rank: Super Contributor
timestamp: May 16, 2014, 06:27:07 am
content: If it bounces is dead, if it sounds like "thunk" and doesn't bounce then it's good.Other than that, yeah, they are made both ways, although in the US I've never seen the non AAAA ones.Btw, 9v are batteries the rest are piles. Although I remember seen some 12V bateries with piles inside too. But it's late so I'm not looking it up

author: vk6zgo
author_rank: Super Contributor
timestamp: May 16, 2014, 06:37:20 am
content: Quote from: miguelvp on May 16, 2014, 06:27:07 am"Battery" just means a group of Cells connected together to obtain a higher voltage or current capacity.The construction of the Cells is immaterial.

author: miguelvp
author_rank: Super Contributor
timestamp: May 16, 2014, 06:38:53 am
content: Quote from: vk6zgo on May 16, 2014, 06:37:20 amTherefore a 9v is a battery a 1.5V is a pile (or cell)