To test an alternator you use a carbon pile. To load test a battery all you need is a variable resistance load. Most service stations have such a device. To test a battery's state-of-charge you MUST put a load on it to remove any surface charge and to see how fast the voltage drops in relation to the load. What you are really measuring is amp/hours referencing the voltage to a known ampere load. You cannot just stick a voltmeter on a battery and from that reading tell if it is any good. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@...> wrote: > > David, > Did I say anything about Amp's. I was talking about battery condition and > it's state of charge. > If you want to test the current / amps condition of the battery the correct > way you need to find someone that has a carbon pile tester. There expensive > so you may have to call around to find someone that has it. > John Hervey > www.specialtauto.com > > > > -----Original Message----- > From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of > David Teitelbaum > Sent: Thursday, August 02, 2007 8:34 PM > To: dmcnews@xxxxxxxxxxxxxxx > Subject: Re: [DML] power drains.... > > You cannot infer from a simple voltage reading what the ampere > capacity of a battery is. It takes a load test to determine that. Most > places will do it for free in the hopes of selling you a battery. If > you let a new battery go completly dead several times you may have > killed it. Lead-Acid batteries do not take kindly to being completely > discharged. > Pull all of the fuses. Put an ammeter in series with the battery. > Install the fuses one-at-a-time and watch the ammeter. When it jumps > up you will know which circuit is the problem. A battery Master Switch > is also useful. > David Teitelbaum > vin 10757 > > > > --- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@> wrote: > > > > Andy, > > 12.66 volts the battery is at 100%, 12.5 volts the battery is at > 80%, 12.2 > > volts the battery is at 40%. That's why at 12.2 volts it most likely > won't > > start. > > John Hervey > > www.specialtauto.com > > www.deloreanautoparts.com > > > > > [moderator snip] > > > To address comments privately to the moderating team, please address: > moderators@... > > For more info on the list, tech articles, cars for sale see www.dmcnews.com > > To search the archives or view files, log in at > http://groups.yahoo.com/group/dmcnews > Yahoo! Groups Links > To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/