Electric Pattern

[mdarr00 at comcast.net]

    Bill, you are correct about a cars alternator putting out 100 amps.  Some put out less, maybe around 80 amps, and some put out as much as 130 amps.  The concern is that they do not put out that much current at idle.  At best they may put out 20 amps.  Before you get the max amperage output of an alternator, you would need to rev the engine to approx 2,000 rpms.  Obviously if you had the hood open the underhood lamp would also be on, your engine is running, so you have the ignition system, cooling fans, engine computer, and all of the sensors needed to make the engine run drawing current.  Having said that, now you add your battery charger, that may or may not put you over what your alternator may put out at idle and now you are running on just the car battery.  While this is happening the alternator is trying to keep the battery charged to the best of its ability which is not much at idle, causing the alternator to burn up.  Food for thought.

Mike Darr
  ----- Original Message ----- 
  From: Bill Glaze 
  To: discussion at nsrca.org 
  Sent: Sunday, August 10, 2003 3:56 PM
  Subject: Re: Electric Pattern


  I can't imagine burning out a perfectly good alternator that is rated for 100 amps by just charging a battery.  I've done it so many times.  Yet, I suppose if there was something else going on, it sure could happen.  I mean, this mechanic said he's seen it.  It's just hard to imagine--my alternators put out ~14.7 volts x 100 amps. = 1,470 watts.  Lots of current.  Last time I looked, that's more than a large TV uses, or even a 2 slice toaster.  I'd like to know what the DC current draw is on Jason's chargers.) 
  Oh, Well. 
  Bill Glaze 
  Ron Van Putte wrote: 

      
    Bill Glaze wrote: 

      Word I got  was $750 per pack for Jason's setup, and 1-1/2 hr. charge time.  Don't know the power source for the charger.

    Tony Stillman reported from Poland that he went to a local car parts place and bought a car battery and car battery charger for Jason to use in lieu of charging from the car's battery while it was running. 

    Ron Van Putte 

      ArestiPattern at aol.com wrote: 
        I'm thinking this new e-pattern flying might be pretty trick to try.  As far as costs go, I'm a bit concerned about the battery packs and charger needs.  I've read the Li-Polys Jason's using are about $325 bucks each so $700 for the plane (that'll come down in price for sure).  So, if I head to the flying field after work to bang off 4 to 6 practice rounds in a couple of hours, how many battery packs and chargers am I gonna have to buy to get this done?  Will I be carrying a Honda portable generator along to power my 'bank' of chargers as well?  What is the re-charge time for one pack? 
        I peeked in the Hacker booth at the last TOC, really impressive stuff and an awesome halftime show each day.  Granted, they were setup to fly several models at the show, but the spaghetti of wires and chargers they had to get this accomplished simply twisted the mind. 

        Rick Hannah 
        St. Joseph, Michigan

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