> I have Macs that have new and good PRAM batteries but a lot of times the > machines act like the PRAM battery is bad. Is there a AHT or something > like one that tests that section of the machine and system? It always > seems to be a crap shoot as to weather the PMU or battery is bad, A volt > meter will quickly test the battery but mining one can be a PITA.
Most Macs utilize a (nominally) 3.6 volt, 1/2AA lithium battery. These will read over 3.68 volts when new. When reading below 3.2 volts, many Macs will start to have RTC, PRAM or other problems, while other Macs will be OK down to 3.0 volts, and possibly below 3.0 volts. However, the battery is essentially dead when it reaches 3.2 volts. I discard any batteries which read below 3.2 volts, and I view with strong suspicion computer problems which occur with a battery which reads 3.2 volts, and I routinely re-confirm computer behavior with a fresh battery. I would not do work for others which left them with a battery which read less than 3.6 volts, and I prefer 3.68 volts for my own computers. Be aware that a DVM or DMM has an internal battery (actually, one or more), and that the DVM/DMM battery is also part of the "reference" circuit for computation of voltage (and resistance and possibly other measurements, but primarily voltage and resistance) and a worn-out internal battery in such an instrument can lead to mis-read voltages and resistances. For example, it is possible for the voltage on a nominally 3.6 volt, 1/2AA battery to read over 6 volts, if the internal battery of the DVM or DMM is nearly worn-out. If suspicious reading are obtained, replace the internal battery, or retest using a known voltage source. For example, the ac line voltage is usually about 125 volts, but it could be as low as 115 volts or as high as 135 volts. If your DVM or DMM, when set to read ac volts, reads significantly outside the range of 115 to 135 volts, you should immediately suspect the instrument's internal battery, and discount any readings taken of any other batteries under test. -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
