Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!zaphod.mps.ohio-state.edu!ncar!umigw!mthvax!wb8foz From: wb8foz@mthvax.cs.miami.edu (David Lesher) Newsgroups: sci.electronics Subject: Re: Car Battery Rechargers Message-ID: <1990Oct15.202407.13654@mthvax.cs.miami.edu> Date: 15 Oct 90 20:24:07 GMT References: <1990Oct4.222556.20668@athena.mit.edu> <63220@iuvax.cs.indiana.edu> Reply-To: wb8foz@mthvax.cs.miami.edu (David Lesher) Distribution: na Organization: NRK Clinic for habitual NetNews Abusers Lines: 28 >Caution is advised if you have an electronic ignition system on your car. >Some cheaper models can turn into smoke when jump-starting. Disconnecting >the positive terminal of the helping car should make things safe, It's not clear if he means disconnect the jumper cable, or the *battery* cable. NEVER disconnect the battery on a running car. This is referred to as a "load dump" and generates the worst possible transient voltages. The battery is an essential low impedance element at frequencies above DC. Without it, the inductance of the field is such that the electronics will be history before the voltage regulator can get things down to where they belong. The best way to avoid problems is patience. Hook up the cars. Sit and let the weak one charge for a while. (10 minutes maybe) Once the other car is running, you can let the good car idle down, and maybe if you want, turn on all of its loads: headlights, heater, etc. Them disconnect the cables. For more details on load dumps, see the GE MOV Engineering Handbook. -- A host is a host from coast to coast.....wb8foz@mthvax.cs.miami.edu & no one will talk to a host that's close............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335