On 1/29/2014 9:37 PM, RussellMc wrote: > Comment on the following is welcomed. > > The following are (stated said to be by the source) statements by the > actual manufacturers of each of the NimH brands involved. > > Avoiding high temperature storage is a major requirement of successful > longer term storage. > Not having any load applied is also very important. > > Note general advice re loss of charge with time and a need to recharge > several times on first use before full capacity is reached. > > General advice on new NimH is that they do not attain full capacity for > "several" cycles. With manufacturer-new cells my experience has been that > they are largely at full capacity by the 2nd cycle. YMMV. With stored cel= ls > this could take more cycles, as suggested below. > > My personal experience with older well used NimH cells is that charging > them on a regular basis is liabl;e to keep them in good condition longer. > As always, YMMV. > > > Russell > > __________________ > > *From: http://www.powerstream.com/Storage.htm > * > > NiMH (Nickel Metal Hydride) Battery Storage Duracell NiMH Battery Storage > > > Ni-MH batteries can give years of safe and reliable service if they are > used in accordance with recommended procedures and are not abused. > Batteries should be kept clean and dry both during use and storage. They > can be stored for many months in a charged or discharged state without an= y > detrimental effects as long as they are not exposed to extreme temperatur= es > for any long period of time. After periods during which the battery has n= ot > been used, the battery should be charged before being placed in service. > Extended overcharging or overheating of the battery should always be > avoided. > > Varta NiMH: Battery storage in any state of charge is possible. Storage > temperatures between -20 and +35 are recommended, relative humidity > approximately 50%. In case of long term storage cells must be recharged > once a year. > > *Sanyo NiMH*: Under the recommended storage conditions (-20 C to +35 C) t= he > Twicel can be stored indefinitely in either a charged or uncharged state. > Recovery may take several cycles. If a battery is stored for a prolonged > time connected to a load, electrolyte fluid will leak, the battery will > begin to deteriorate, and capacity will be impaired after storage. During > long time storage battery deactivation may tend to occur, and for this > reason charging may stop early during recharging after storage. This > problem can be solved by charging and discharging the battery several tim= es. > > *Sanyo NiMh Battery Storage*: Generally speaking, a loss of voltage and > capacity of batteries due to self-discharge during storage is unavoidable= .. > The factors inducing this self-discharge of Nickel-Metal Hydride batterie= s > is listed below: > > 1. The inside of the cell is a hydrogen atmosphere at low pressure, > which gradually reduces the active materials at the positive electrod= e, > resulting in a drop of cell capacity. Accompanied by this, the negati= ve > electrode which is thermodynamically unstable in its charged state > gradually gives off hydrogen gas, thus reducing cell capacity. > 2. The active materials at the positive electrode in its charged stat= e > self-decompose, causing the cell capacity to decrease. > 3. Impurities within the cell, especially nitric ions, are reduced at > the negative electrode and diffuse to the positive electrode where th= ey are > oxidized. This results in a lowered cell capacity. > > The factors (2) and (3) also apply to Nickel-Cadmium Batteries. As > discussed above, the self-discharge of Nickel-Metal-Hydride Batteries > during battery storage causes a loss in stored energy. However, once > recharged, this lost portion of the capacity will be almost completely > restored. The self-discharge characteristics of Nickel Metal Hydride > batteries is affected by storage temperature. . . If the battery is store= d > at high temperatures, the self-discharge will be accelerated. Also, the > longer the storage period, the more the cell capacity decreases. As > mentioned above, since the capacity of Nickel Metal Hydride batteries los= t > by self-discharge can be restored by recharging, there are virtually no > noticeable adverse effects of battery storage. However, prolonged storage > at high temperatures may deteriorate or deform the gasket or the separato= r, > and should be avoided. Either fully charged or discharged, Nickel Metal > Hydride ( NiMH ) batteries may be stored indefinitely. . . In either case= d > (charged or discharged) the capacity is recovered within two or three > charge / discharge cycles. > > Panasonic NiMH Battery Storage > Because long term storage can accelerate battery self-discharge, and lead > to the deactivation of reactants, locations where the temperature ranges > between +10=B0C and +30=B0C are suitable for long term storage. > > When charging for the first time after long term storage, the deactivatio= n > of reactants may lead to increased battery voltage, and decreased battery > capacity. Restore such batteries to orginal performance by repeating > several cycles of charging and discharging. > > When storing batteries for more than one year, charge at least once a yea= r > to prevent leakage and deterioration of performancedue to self-dischargin= g. > > > __________________ > > Some advice here. > Sounds good. > Quality unknown: > > http://www.camlight.com/techinfo/techtips.html Russell, what does YMMV mean? --=20 The only place success comes before work is in the dictionary. VINCE LOMBARDI --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .