Re: CS>Answer to Catherine, warning to Mike Monett... From: Marshall Dudley Date: Mon, 23 Jun 2003 09:41:21
> This guy is claiming to be a Ray-O-Vac engineer? I have my doubts. Boy, posting in html sure garbles things. Yes, he is a reliability engineer for batteries, and he knows what he is talking about. > Putting a partially discharged battery in series with good ones > will not cause a reverse current, but can cause a current to be > forced through it when it becomes totally dead which might be a > problem. This is exactly the problem. Current flows in the reverse direction as he described. This causes gas to build up. Batteries that are not designed for recharging have no way to vent this gas. Eventually the battery explodes. > To get a reverse current requires the battery to be installed > backwards, or in parallel with one or more batteries that are not > discharged. Out of 3 possibilities, he chose the one that was > wrong. No. When the batteries are in series, the strong batteries charge the weak one in the reverse direction. This is called cell reversal. If the battery is not designed for recharging, gas buildup causes the battery to explode. > Regular batteries are in a steel can also for most types, such as > a C or D cell. He should know that if he is a battery engineer. > Marshall As he described, carbon-zinc batteries have a zinc outer shell. Here is a picture from the Energizer site: http://data.energizer.com/batteryinfo/cross_sections_for_manuals/cs1215.pdf Alkalines have a steel outer shell insulated with plastic. There is a picture on the Energizer site at this url: http://data.energizer.com/batteryinfo/application_manuals/cylindrical_alkaline.htm Alkalines that are not designed for recharging usually have a printed warning stating "Do Not Recharge". The gas buildup causes the battery to explode when the pressure gets high enough. The problem is putting a weak battery in series with fresh ones. Shorting a battery stack causes a very high current drain. This is extremely dangerous. The battery does not heat up. There is no warning. It just explodes. The Energizer "Design and Safety Considerations" states this clearly, but uses euphanisms that do not indicate the true danger: http://data.energizer.com/batteryinfo/other_available/design_and_safety_considerations.htm "b. Instruct the consumer to replace all batteries at one time." "The replacement of a partial set or mixing batteries from the different chemical systems exposes the device to the possibility of electrolyte leakage and damage through over-discharge of the lower capacity batteries." Translation: Alkalines suffer from cell reversal and will explode if charged in the reverse direction. "c. Advise the consumer that batteries that are not specifically designed to be recharged can leak and in, some cases, rupture if recharged." Translation: They will explode. On the Alkaline Applications page, they finally come out and admit the danger: "Charging of Primary Batteries" "Charging of primary batteries may cause explosion or leakage which may result in bodily injury." "IF ENERGIZER/EVEREADY PRIMARY BATTERIES ARE SUBJECTED TO ANY FORM OF RECHARGING, ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE NULL AND VOID." (Sorry - they are shouting, not me:) "Metal-Jacketed Batteries" "It is important to note that some batteries have metal jackets." (Actually, they all do. But the Alkalines are made of steel and are sealed tight. Carbon-Zinc have a zinc outer shell and an insulator covering the top. The insulator will give way with very low pressure, so there is no danger of explosion.) "Proper design of devices using these batteries should include electrical isolation of the battery jacket from the device circuitry to prevent short circuiting." "Short circuits may cause battery explosions or leakage which may result in bodily injury." http://data.energizer.com/batteryinfo/application_manuals/cylindrical_alkaline.htm Marshall, does this help? Best Regards, Mike Monett -- The silver-list is a moderated forum for discussion of colloidal silver. Instructions for unsubscribing may be found at: http://silverlist.org To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
