Talk:Ampere-hour

Topics from 2006

E=QV

It says here E=CV, though I doubt this is the case. C is commonly used for capaciTANCE (a different yet extremely common parameter in electricity) while Q is used for charge. While it's possible in the same circles where mAh are used, (rather than Coulombs) C is used for capacity, I doubt this. -Oreo Priest ((talk)) at 02:05, 9 June 2006

Unit of measurement

Variables should not have an associated unit of measurement. Those equations should be correct *despite* ones use of units (as long as the units are properly tracked). Fresheneesz 02:11, 12 August 2006 (UTC)

Battery description

All the stuff about batteries should be moved to the battery (electricity) article. Articles about a unit of measure should not be dominated by one use of that unit. --Wtshymanski 22:34, 17 November 2006 (UTC)

sorry, I don't agree, I've just been looking this unit of mesurament up in regard to batteries details and that info has been very useful to me. —192.33.238.6 (talk) 15:30, 5 April 2007 (UTC).

Ummm... I was just about to add all that stuff, not realizing you deleted it. You didn't even include a link? — Omegatron 02:49, 14 September 2007 (UTC)

17-Oct-2008: (1 year later) I have added some small examples, using batteries, to help relate the terms "ampere-hour" or "mAh" for general users, as in cordless phones or iPod batteries. Examples don't have to cover a vast array of applications, just provide some common-place use of the concepts. After revising many complex articles (tagged "too-technical"), I've found that using examples can often simplify the wording, while an abstract, precise definition is often tagged as "too-technical" for general readers. A mathematically pure set of ideal, abstract articles just will not work for informing general readers about units of measurement. However, a hybrid approach has worked by splitting articles into sections, where math formulas can be expanded in particular sections of the article. -Wikid77 (talk) 15:12, 17 October 2008 (UTC)

Am I missing something?

[...] a CD player draws a constant current of 200mA from two rechargeable AA batteries that have a capacity of 2300mAh each. So, 2.300Ah / 0.200A = approximately 11.5 Hours of battery life.

I am not well versed on electricity, but if we are talking about 2 batteries with a capacity of 2300mAh each, wouldn't that bring the total amount of capacity to 4600mAh? The CD Player on that example would then last 23 hours... --CronoT 15:31, 20 December 2006 (UTC)

The batteries are connected in series, giving a total voltage of 3 V with a capacity of 2300 mAh. The same current flows through both batteries. Would they be connected in parallel, the voltage would be 1,5 V, with a total capacity of 4600 mAh. LHOON 15:39, 20 December 2006 (UTC)

Heh, that was fast! :-) Thanks for the clarification. Maybe this should be clarified on the article as well, for the sake of newbies like me. --CronoT 16:56, 20 December 2006 (UTC)

Done. LHOON

Topics from 2007

SI

Which is the SI metric equivalent ?. --Nopetro 21:48, 21 May 2007 (UTC)

Since 1960 it would be Ampere-hours. http://en.wikipedia.org/wiki/Coulomb#Historical_note Memobug (talk) 23:53, 2 August 2008 (UTC)

Why don't they use Coulombs to tell battery capacity? I think the current usage is as dumb as telling distances in knot-hours, even if all are correct. Alvaro --212.81.220.70 (talk) 14:13, 24 November 2008 (UTC)

3600 C = 1 Ah, probably the same reason we use kWh and not MJ. --

Topics from 2008

Retrofit topic year headers

17-Oct-2008: I have added subheaders above as "Topics from 2006" (etc.) to emphasize the dates of topics in the talk-page. Older topics might still apply, but using the year headers helps to focus on more current issues as well. Afterward, I retro-dated/named the unsigned comments. -Wikid77 (talk) 15:12, 17 October 2008 (UTC)

Redirection titles

17-Oct-2008: Beyond title "Ampere-hour" the following terms also link to the article as redirection titles:

• amp-hour, Ah, mAh, A/h, A/H, milliampere-hour,
• milliamp-hour, milliampere-second, milliamp-second, mAs.

There might be other associated titles as well; however, they should only be defined as redirection-titles in Wikipedia if commonly used. Otherwise, users can run a wiki-search for any term to find any related wiki articles which contain/define that term. There is no need to define a wiki-name for every term which could be found by searching. -Wikid77 (talk) 15:12, 17 October 2008 (UTC)

A/h and A/H (amps per hour) is technical nonsense and has nothing to to with ampere hours. This is a misuse of the letters A and h in this context and should not be encouraged. A gradient of rising or falling current should be dealt somewhere else. Anyway, it is very rarely used according to recent statistics. The lemma should be deleted, as the wiki search function is distracted by alternatives which mean nothing. --Gunnar (talk) 23:08, 17 September 2020 (UTC)

thank you, editors of these science articles!

it helped me sooo much in my schoolwork, i know i forgot 2 log on but who cares, andyway, thank the editors who did all the nerdy scientific contributions!!! you saved my life and it's certainly better than my science teacher's boring lessons 78.105.31.170 (talk) 17:35, 23 October 2008 (UTC)

[ah] is an abrevyasion for ampere hour witch is E=QV witch i have no idia what it is! when you tern on the lights the light bulb can get up to 2,200 degrease c. also when a light bulb lights up the fliliments in the adums start vibrating and they heat up during that proses. —Preceding unsigned comment added by 65.117.213.17 (talk) 01:01, 28 February 2009 (UTC)

Power? Energy?

Twinkle twinkle little star, power equals $I^{2}R$.... My concept of a battery is something that stores energy, not electrons. How is mAh a useful measure of a battery? I suppose I can multiply by the voltage (assuming a constant voltage) and get that a 1,000 mAh battery at 1.5 V is 5400 joules or 1.3 kcal... But (a) that sounds like too much energy (over a half a day's food in one AAA battery!?) and (b) Why don't battery manufacturers talk in units of energy? Or is there something about the chemistry of batteries that makes this more meaningful (like rocket engineers using specific impulse)? —Ben FrantzDale (talk) 01:20, 8 October 2009 (UTC)

a) You don't eat 2.6kcal a day, do you? b) Rechargeable batteries at least, talk in mAh. —Preceding unsigned comment added by DarknessEcko (talk • contribs) 20:25, 7 June 2010 (UTC)

Yes, a battery does store energy in the form of chemicals that are about to react together. Your calculation looks correct to me. I have no idea why mAh was chosen over J. I could make a calorimeter and test how much heat I can transfer to some water. My power company chooses to give me energy usage as kWh. The only explanation I can come up with is that the decision was made by politicians/engineers rather than scientists. Vmelkon (talk) 02:15, 26 November 2019 (UTC)

The reason is that the active material in a battery can accept a certain amount of electrons. The electric charge going in and out is constant, whereas the electric energy is not due to the losses in the conductors and the battery cell itself (internal resistance). Therefore, you cannot guarantee how much energy you get out of a fully charged electrochemical cell: this depends strongly on the current (rate of discharge). Therefore the energy content of a battery is only nominal and just a rough indicator, whereas the electric charge in C or Ah is real. --Gunnar (talk) 23:27, 17 September 2020 (UTC)

Topics from 2010

Redirects

If you type mAh on the address bar you get to MAh, which gets you to Ampere-hour.

What i'd like to address is that lowercase makes a real big difference in electricity, and so the redirect should not actually happen. —Preceding unsigned comment added by DarknessEcko (talk • contribs) 20:21, 7 June 2010 (UTC)

kW

Is there any relation with kW or kWh?. --Nudecline (talk) 12:09, 24 June 2010 (UTC)

No. They are measuring different things - amperehours are measuring charge, and kw and kwh are measuring power and energy. If, for example, you knew what the voltage and current was at all points of discharge of a battery, you'd be able to work out the power, energy, and charge transferred, but Ah alone is insufficient information. You could walk from Kenora to Saskatoon and it would take you days, or you could drive it in less than a day, or travel over the two places in a jet in an hour, or an Earth-orbiting satellite covers the distance in a minute or so...knowing the distance between two cities doesn't tell you how long it will take to travel between them unless you know a lot more about the problem. Of course you can say that, all things being equal, Kenora to Saskatoon will take less time than St. John to Vancouver or London to Tokyo. --Wtshymanski (talk) 13:04, 24 June 2010 (UTC)

I see that due to all the fighting about what should and shouldnt be in the article, the article is now ..

useless........ there is no information here. Its far better to have way too much information even if its not 100% relevant than it is to have a 2 paragraph article that explains just about NOTHING!! add more information! — Preceding unsigned comment added by Gawdsmak (talk • contribs) 04:21, 11 November 2013 (UTC)

Here here! Three cheers! There's more useful information in the talk page than there is in the article. What's up with that?---Puff (talk) 22:55, 16 May 2014 (UTC)

my tab sm-t211 battery problem created, 100% charge within 10min gone 99% but 1% 2hour living battery shows always 1%

Please solve my problem Rony2543 (talk) 21:17, 24 December 2015 (UTC)

Topics from 2016

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Hyphen

There is a rule in ISO/IEC 80000-1:2009 "Quantities and units -- Part 1: General":

7.2.4 English names of compound units

In the English language, the name of the product of two units is the concatenation of the two names, separated by a space.

EXAMPLE 1 newton metre

Therefore, I argue to remove the hyphen and use "ampere hour" instead. --Gunnar (talk) 13:13, 2 November 2016 (UTC)

Let us understand: you are cherry picking the rules you like, negating the importance of the SI and NIST rules, despising the American and English common use language, and, in the process, distrupting redirects and wiki-links ? --Robertiki (talk) 15:10, 25 January 2017 (UTC)

And beside, you shouldn't move a page without a previous discussion, and anyway, unless you are willing to do repair. There are almost 500 wiki-links pointing to Ampere-hour. --Robertiki (talk) 16:20, 25 January 2017 (UTC)

As far as I know the English grammar, a hyphen may be used for instance to concatenate two adjectives such as "high-voltage transmission line", the hyphenated compound refers together to the main expression. Which hyphen rules did you cite as an argumentative support. BTW, I just found the NIST Guide for the Use of the International System of Units (SI), 2008 on pages 45 and 58 they use "ampere hour" without hyphen. --Gunnar (talk) 15:38, 14 September 2020 (UTC)

FYI, Wikipedia has its own rules regarding the use of hyphens, which take precedence over any external sources such as Grammarly.

Also, the SI explicitly accepts both spaces and hyphens. From section 5.3 of the SI brochure: "When the name of a derived unit is formed from the names of individual units by juxtaposition, either a space or a hyphen is used to separate the names of the individual units."

The Wikipedia Manual of Style section on unit names and symbols agrees: "Indicate a product of unit names with either a hyphen or a space."

Therefore, I question the utility of the mass edits you've been making to articles of various mobile devices, especially since in most cases you're changing the target of a piped link, rather than the text that is actually shown on the page. Indrek (talk) 06:15, 18 September 2020 (UTC)

Rules for concatenation of adjectives are irrelevant. This is about multiplication. I do think it makes sense to choose between a space and a hyphen, and stick to that. My personal preference is a space, but consistency between (and within) articles is more important than my (or anyone else's) preference. Dondervogel 2 (talk) 18:30, 25 September 2020 (UTC)

Energy capacity

"The ampere-hour is frequently used in measurements of electrochemical systems such as electroplating and incorrectly, the capacity of electrical batteries." - Why is it incorrect to use Ah for electrical batteries? It should be clear that not the energy capacity is meant, but an electrochemical cell like a battery is full if the material inside is 'saturized' with enough electrons. --Gunnar (talk) 13:32, 2 November 2016 (UTC)

Ampere-hour is not a energy unit, but a unit of electric charge, so I don't understand your reasoning. The ampere-hour is a count of the available electrons in a battery. --Robertiki (talk) 16:11, 25 January 2017 (UTC)

"and incorrectly, the capacity of electrical batteries" - my mobile phone battery says "1450 mAh" - that is a capacity of 1.45 Ah = 3600*1.45 As = 5220 C. It says nothing about the energy content or energy capacity, as the exact voltage is unknown, but tells something about the active material on the electrodes. Therefore it is not wrong to specify the capacity (either in Coulomb) of electrical batteries or in ampere hours. --Gunnar (talk) 15:44, 14 September 2020 (UTC)