Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!netcom!fiedler From: fiedler@netcom.COM (David Fiedler) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: Need Help Building External Battery Pack for Laptop Keywords: EXTERNAL BATTERY PACK LAPTOP Message-ID: <1991Apr24.061514.5505@netcom.COM> Date: 24 Apr 91 06:15:14 GMT References: Distribution: usa Organization: Netcom - Online Communication Services UNIX System {408 241-9760 guest} Lines: 30 srm@dimacs.rutgers.edu (Scott R. Myers) writes: >I have salvaged from an old UPS 4 6volt Panasonic Lead Acid Batteries. >I would like to use them in a case as a backup battery pack for my >portable office (laptop,cellular phone,etc). Questions I have are >concerning differences in voltage and amps. >1) My laptop (Sharp MZ200) takes in 9VDC 2.5amps converted from >household current. The Cellular phone plugs directly into my >cigarette lighter. I'm not sure how I should set up the batteries to >provide current to these devices and not blow them up. Any ideas? >Also to add I would rather work with just 2 of the 4 6volt batteries. You only need two 6 volt batteries to make 12 volts! Put them in series, positive from one battery to negative on the other. This will give 12 volts. Now mount them in a case without metal inside and with a vent hole so you won't build up hydrogen when recharging, and hook up a female cigarette lighter socket (Radio Shack sells them). The red wire (positive) goes to the battery positive. Now get a car battery charger to recharge this 12 volt pack (for faster work put a male cigarette lighter plug on it to replace the alligator clips). This will work perfectly with your cellular. As far as the laptop, forget it! You would need a high current DC-DC converter or a big resistor that would just give off heat. -- David Fiedler UUCP:{ames,mrspoc,hoptoad}!infopro!david AIR: N3717R "Video for Computer Professionals" BIX: fiedler Internet: fiedler@netcom.com USMail:InfoPro Systems, PO Box 220 Rescue CA 95672 Phone:916/677-5870 FAX:-5873