da0g+@andrew.cmu.edu (David Apfelbaum) (03/23/91)
My Zenith-183 (8088, 10M harddrive) is suffering from a dead battery. Because of the way the power system is designed, the computer is unusable. (The circuitry that detects a low-power situation and inactivates the computer is wired solely to the battery.) I have talked with the people at Heath/Zenith and they want $175 for a replacement battery-pack. They also recommended I get the power-supply-circuit "re-tuned" so that it is producing the proper voltage levels, which would cost an additional $65. Now knowing what I do about modern power-supply design and the price of hi-capacity nicads, I feel that I am being "Taken". The battery pack should cost less than half the price that they are asking. And can the power supply circuit even be "Tuned"??? But there is another problem. The computer charges the battery-pack whenever it is plugged in -- Not just when the power is off! As a result, the battery pack gets seriously trashed! According to one Zenith person that I talked to, I am supposed to run the computer off the batteries until they die, and then continue by running off the power supply. This is inconvenient when I am running long number-crunching programs. And while this will make the batteries last longer than they currently do, they will still be wearing out faster than they should be as nicads only have a limited number of charge/discharge cycles. (It is also not mentioned in my owners manual -- How convenient for them! :-( I did talk to the people at Heath/Zenith about hooking up my own battery -- or just disconnecting the charging circuit. They assured me that if I were to try such a thing, I would surely burn out my computer. Now this is something that I wish to avoid. However, it strikes me that if such a thing was possible, Heath/Zenith would be the first to deny it -- Based on the profit motive. And it can't really be all that difficult! So my questions to the net are: (1) Is it possible/feasible to hook up my own battery? And if so, how? And (2) Is it possible to disconnect the charging circuit without damaging the computer? Or just limit it to charging when the computer is turned off? I have no problems with building my own external charger, if it's necessary. Does anyone have any ideas? It really irks me to just be "Taken"! Thanks, -David Apfelbaum. =========================================================================== David Apfelbaum Student (mostly Math/CS) at Carnegie Mellon. 5266 Beeler St. INTERNET, BITNET, etc: da0g+@andrew.cmu.edu Pittsburgh PA 15217 Alternate: da0g%andrew@CMCCVB (412) 683-7216 UUCP: ...!harvard!andrew.cmu.edu!da0g =========================================================================== #include <std_disclaimers> /* CMU is not responsible for my babblings. */ #include <std_quote(s)> /* Beware of Hackers carrying screwdrivers. */ ===========================================================================
RON@psuvm.psu.edu (Ron McCarty) (03/27/91)
In article <EbuYnNG00VovAiVVVG@andrew.cmu.edu>, da0g+@andrew.cmu.edu (David Apfelbaum) says: > > My Zenith-183 (8088, 10M harddrive) is suffering from a dead battery. >Because of the way the power system is designed, the computer is >unusable. (The circuitry that detects a low-power situation and >inactivates the computer is wired solely to the battery.) > I don't understand. My 183-92s batteries have been dead for almost a year now but it hasn't prevented me from using the machine. I simply removed the battery pack and use it exclusively on ac with the powerpack. I have had no problems doing this. > > But there is another problem. The computer charges the battery-pack >whenever it is plugged in -- Not just when the power is off! As a >result, the battery pack gets seriously trashed! According to one This is why i didn't bother to buy new batteries. Given the deficient design of the machine (the fact that the batteries are always charging) I could see that the new batteries were just going to get trashed the way the originals did. And you are right, using it off batteries until they die is not the way i want to use my machine. I usually have access to ac and prefer to have the machine plugged in. The batteries (when I ha had them) were a nice backup when the power went off or for those rare occasions when i didn't have access to ac. Ironically, it is the fact that i always used ac rather than the batteries that destroyed the batteries. Ron McCarty Penn State Erie
da0g+@andrew.cmu.edu (David Apfelbaum) (03/28/91)
> Excerpts from netnews.comp.sys.zenith: 26-Mar-91 Re: Questions on > Zenith-183.. Ron McCarty@psuvm.psu.ed (1512) > I don't understand. My 183-92s batteries have been dead for almost a > year now but it hasn't prevented me from using the machine. I simply > removed the battery pack and use it exclusively on ac with the > powerpack. I have had no problems doing this. Thats strange. I wonder if we have different editions. My system has a diode network that prevents me from doing this. It looks like this: (This is a little simplified, there are other components, but this is the basic problem.) To low-power warning and auto-system shutoff. || || battery positive -----++-------Diode-- To rest of system power supply. Basically, this diode prevent me from doing just that -- running solely off AC. And because of the way the charger circuit works, the battery gets trashed really easily. My basic question is how to get around the problem without destroying the computer. Is it possible to hook up a external battery or DC power supply without connecting up the charger circuit AND without destroying/damaging the computer? I know that the zenith battery-pack contains several solid-state devices. Does anyone know what they do? I am assuming that they are either part of the charging circuit, or some sort of overload device. (I'm guessing.) Does anyone out there know how to do this (hook up a home-made external DC power system (ie either a battery or a DC power supply) to the computer's battery connections) SAFELY? Does anyone have any clues as to how this system works? Or should I just try it and hope/pray for the best? Thanks, -David Apfelbaum. ========================================================================= == David Apfelbaum Student (mostly Math/CS) at Carnegie Mellon. 5266 Beeler St. INTERNET, BITNET, etc: da0g+@andrew.cmu.edu Pittsburgh PA 15217 Alternate: da0g%andrew@CMCCVB (412) 683-7216 UUCP: ...!harvard!andrew.cmu.edu!da0g ========================================================================= == #include <std_disclaimers> /* CMU is not responsible for my babblings. */ #include <std_quote(s)> /* Beware of Hackers carrying screwdrivers. */ ========================================================================= ==