---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 12/23/12: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:26 PM - Problem with the Harbor Freight Carbon Pile battery tester (Bill Watson) 2. 06:38 PM - Carbon Pile battery tester (Paul Millner) ________________________________ Message 1 _____________________________________ Time: 04:26:53 PM PST US From: Bill Watson Subject: AeroElectric-List: Problem with the Harbor Freight Carbon Pile battery tester I've used this unit a few times without a problem. Then it suddenly stopped working. I couldn't seem to apply a load though the exact symptoms I don't quite remember. Today, I pulled the unit apart and found 1) a fuse on a small circuit board which had not blown (not easily replaceable either) 2) the carbon disks that presumably supplies the variable resistance seem to be stacked between two steel plates but the carbon disks appeared to be loose or askew. If I screw the big knob down and shake things a bit, I can get the stack of carbon plates lined up and it seems that increased resistance results from placing more pressure on the stack. Does that sound right? Furthermore, it would seem for consistent operation, it would be best to lie the unit on its back to insure the carbon plates remain flat. Tomorrow I will attempt to use it again to see if it works now that the plates are back in position. Any insight or tips welcome. I will report further tomorrow. Thanks Bill ________________________________ Message 2 _____________________________________ Time: 06:38:55 PM PST US From: Paul Millner Subject: AeroElectric-List: Carbon Pile battery tester On 12/23/2012 4:25 PM, Bill Watson wrote: > If I screw the big knob down and shake things a bit, I can get the > stack of carbon plates lined up and it seems that increased resistance > results from placing more pressure on the stack. > > Does that sound right? Don't know about your unit, but traditional carbon piles *decrease* resistance as you tighten them up, pushing the pack into better contact, or decreasing the total electron path length, depending on how you'd like to think about it. Relaxing pressure *increases* resistance, as the carbon gets further away from each other, at least microscopically. At least, our 1937 2400 volt AC generators' excitation current control widgets work that way... technology may have marched on in the interim. Paul ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.