Talk:Nickel–metal hydride battery/Archive 2

Memory Effects

I came to this article to know whether NiMH batteries (as in my home wireless phone) suffer from the need to be fully discharged before recharging. Why is this not mentioned, at least in the section that compares different types? Most people won't read the Talk tab. I only came here to ask why there was no mention of this aspect of battery performance. 216.121.185.75 (talk) 00:26, 17 March 2013 (UTC)

Your Ni-NH batteries do not suffer from memory effect. Memory effect is largely a myth. It affected a very specialised type of Ni-Cd battery used in a very specialised application where the batteries were regularly discharged to exactly the same level (and it does have to be exactly the same level). When Ni-MH batteries first appeared, marketing men seized on the hitherto unknown memory effect as a way of selling batteries that offered no significant advantage over Ni-Cd batteries at typically five times the cost. Early Ni-MH batteries offered little more capacity than Ni-Cd, though that rapidly changed as the technology ws developed. I B Wright (talk) 18:27, 17 December 2013 (UTC)

NiMH LSD cells internal resistance is higher not lower than traditional NiMH cells

NiMH LSD cells internal resistance is higher not lower than traditional NiMH cells because the separator is thicker than in normal cells. LSD cells do not have a larger "area" of the separator, which is always equal to the area of the electrodes that it is separating. Instead LSD cell probably achieve their reduced internal leakage current thus reducing self discharge by increasing the thickness of the separator. Since the resistance of any material is proportional to its thickness, this decreases the internal leakage current thus prolonging the time that a cell will hold a certain amount of its charge, but this also would increase the internal resistance of the cell, not decrease it. Wpbobm (talk) 00:11, 6 February 2014 (UTC)

I've been looking for a technical description of the internals of an LSD NiMh for a while now. Have you found a citation for this? --Wtshymanski (talk) 19:55, 7 February 2014 (UTC)

Cell Voltage

I would contest part of the statement "NiMH batteries normally operate at 1.2 V per cell, somewhat lower than conventional 1.5 V cells, but will operate most devices designed for that voltage." In my experience most devices will not operate properly at this voltage and torches are not very bright either. BletchleyPark (talk) 18:46, 24 May 2013 (UTC)

Filament bulbed torches are a little dimmer, but LED based torches are considerably dimmer. I would prefer to see the word 'many' substituted for 'most'. I B Wright (talk) 18:11, 17 December 2013 (UTC)

The statement is made: "NiMH batteries typically lose 4% of their charge per day of storage." This is a false statement, and is at odds with the statement in the sidebar, which more accurately describes this effect as a much smaller amount. Perhaps the author of this meant to say that the disadvantage of the NiCd battery is this, and meaning to say this is why the NiMH is better. Regardless of the reason, the statement made is incorrect. — Preceding unsigned comment added by Kz1o (talk • contribs) 20:07, 22 December 2013 (UTC)

Microprocessor-based products are typically set for a drop-out voltage of 1.25V per cell and will work only briefly if at all with NiMH's. My theory is that the designers have unlimited access to primary cells during product development and it never occurs to them to set a lower d.o.v.Julesomega (talk) 14:58, 14 May 2014 (UTC)

Emergency lights

The article says emergency lights in Europe are to work for four hours after a power cut, but to the best of my information it is only one hour. (For the record: I worked as a facility manager in an office, so I am not just guessing.) 82.139.114.136 (talk) 14:40, 22 October 2012 (UTC)

I removed that from the article. It wasn't even cited. – voidxor ^{(talk | contrib)} 00:08, 18 July 2015 (UTC)

Anode and cathode

This has been extensively discussed elsewhere, but not here. An editor has claimed in a recent edit that the anode is the positive electrode relative to the cathode. This is not necessarily the case. For primary batteries the terms are distictive, but the anode is in fact the negative electrode, the positive being the cathode. If you have a look at the article anode the position should become clear. In a secondary (rechargeable) battery, the terms are ambiguous because the anode on discharge becomes the cathode on charge (and vice versa). 86.153.131.220 (talk) 12:21, 29 October 2015 (UTC)

The terms "anode" and "cathode" are used indistinctly by the manufacturers for primary and secondary batteries to refer to the negative and positive electrodes, respectively. If you are more into theoretical physics then you use different definitions for anode and cathode, which are inverted in the contexts of charge and discharge. If you want to ensure to please both manufacturers and theoretical physicists, you can just say "positive electrode" and "negative electrode", since these properties don't change while charging. In the text you had erased, the term "anode" was referring to the manufacturers' vocabulary. I reestablish the deleted text with "negative electrode" instead of "anode", so the information is given in a fashion that everybody likes instead of being simply erased. Jlbruyelle (talk) 16:08, 29 October 2015 (UTC)

@Jlbruyelle: Good point about my removal of your attempt to define which electrode the gas is formed at - I should have changed it to the current wording. This is an encyclopedia and as such should use the terms 'anode' and 'cathode' correctly (and should be consistent with the articles). I am aware that the battery manufacturers are inconsistent with their use of the terminolgy, but in general it seems to be US based battery and equipment suppliers who use the anode is positive convention regardless, with the rest of the world generally using the terms correctly. As ever, exceptions exist. I do have an HP laptop with a sticker on the motherboard next to the BIOS coin battery that says 'anode up'. It is in fact, impossible to install the battery this way. 86.153.131.220 (talk) 17:28, 29 October 2015 (UTC)

The anonymous user is correct; the anode is the terminal of a device where current enters. It is a common misconception that anode is synonymous with the positive terminal and cathode with negative. Thus, it doesn't surprise me that such misunderstanding exists within battery manufacturers. Wikipedia is a fact-checked encyclopedia and it is our duty as editors to keep such errant sources from being used here. – voidxor 20:11, 29 October 2015 (UTC)

I have removed the wording that implies that gas is only formed at the negative electrode. This is not the case. Only Hydrogen is evolved at the negative electrode. Oxygen is evolved at the positive electrode. This is straightforward electrolysis of the water content of the electrolyte. 86.153.131.220 (talk) 08:39, 3 November 2015 (UTC)