Panasonic Cordless Telephone Battery (HHR-P104A)

This replaces my old land line battery. Works great

Needed some new batteries for all of the cordless phones in the house, so I decided to check Amazon for any possible deals. Batteries are EXPENSIVE as you all know, so I'll take all the help I can get.I stumbled across these batteries available through DependableResource for..$8.95 (at the time of purchase)?! Did I read that right?!This price was SIGNIFICANTLY cheaper than any other retailer's price that I knew of (about $15.00 elsewhere).Of course, you can't have your cake and eat it too, so something like this naturally made us a bit doubtful. I mean, for that kind of deal, there's gotta be some kind of catch, right? Fake batteries, perhaps? But, seeing that the seller had a great rating and excellent reviews, we decided we'd give it a try, and bought three batteries for a total of $26.88 (with Super Saver Discount, therefore no S&H, and no tax) with a cautious "we'll see" attitude. If anything was wrong with the product, we were immediately going to send it back.Well, the batteries arrived, and we were pleasantly surprised to learn that they are GENUINE! Yay! So I guess you really CAN have your cake and eat it too sometimes! :)The only thing I can think of that wasn't even really a problem is that the package took a little while to arrive (about 9 days). But, we were in no hurry, therefore we didn't need the package right away, and didn't need to spend a lot on shipping to get it here quickly. I think we were just excited, that always makes things seem like they're taking forever. :)These guys are the real deal, thanks, DependableResource, for selling my family genuine batteries, and saving us a ton of money! :)

A battery is a device that converts chemical energy directly to electrical energy. It consists of a number of voltaic cells; each voltaic cell consists of two half-cells connected in series by a conductive electrolyte containing anions and cations. One half-cell includes electrolyte and the electrode to which anions (negatively charged ions) migrate, i.e., the anode or negative electrode; the other half-cell includes electrolyte and the electrode to which cations (positively charged ions) migrate, i.e., the cathode or positive electrode. In the redox reaction that powers the battery, cations are reduced (electrons are added) at the cathode, while anions are oxidized (electrons are removed) at the anode. The electrodes do not touch each other but are electrically connected by the electrolyte. Some cells use two half-cells with different electrolytes. A separator between half-cells allows ions to flow, but prevents mixing of the electrolytes.Each half-cell has an electromotive force (or emf), determined by its ability to drive electric current from the interior to the exterior of the cell. The net emf of the cell is the difference between the emfs of its half-cells, as first recognized by Volta. Therefore, if the electrodes have emfs and , then the net emf is ; in other words, the net emf is the difference between the reduction potentials of the half-reactions.The electrical driving force or across the terminals of a cell is known as the terminal voltage (difference) and is measured in volts. The terminal voltage of a cell that is neither charging nor discharging is called the open-circuit voltage and equals the emf of the cell. Because of internal resistance, the terminal voltage of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging exceeds the open-circuit voltage. An ideal cell has negligible internal resistance, so it would maintain a constant terminal voltage of until exhausted, then dropping to zero. If such a cell maintained 1.5 volts and stored a charge of one coulomb then on complete discharge it would perform 1.5 joule of work. In actual cells, the internal resistance increases under discharge, and the open circuit voltage also decreases under discharge. If the voltage and resistance are plotted against time, the resulting graphs typically are a curve; the shape of the curve varies according to the chemistry and internal arrangement employed.As stated above, the voltage developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. Alkaline and zinc-carbon cells have different chemistries but approximately the same emf of 1.5 volts; likewise NiCd and NiMH cells have different chemistries, but approximately the same emf of 1.2 volts. On the other hand the high electrochemical potential changes in the reactions of lithium compounds give lithium cells emfs of 3 volts or more.And it fits perfectly into my old cordless phone.

This is not the OEM battery pictured in the ad. It seems to be a very good battery though, and it takes a charge, and works in the phone as it should, unlike the old battery I had in the phone, which wouldn't retain a charge, and kept giving me an error message, to move the phone closer to base, almost every time I tried to use it.The only reason I didn't give it 5 stars, is because I was expecting a Panasonic OEM battery as pictured, but otherwise I am satisfied so far.