XPost: uk.rec.driving, alt.home.repair, uk.d-i-y   
   From: CFKinsey@military.org.jp   
      
   Modern car alternators seem to be able to give out a huge amount of current at   
   engine idle speed.  I'm sure my friend got his to give out pretty much the   
   full 80 amps without revving the engine.  He was powering a small disco on a   
   campsite :-)   
      
      
   On Sat, 22 Jun 2019 11:00:34 +0100, Brian Gaff    
   wrote:   
      
   > Yes indeed, the nominal output of an alternator can be as high as 15 volts,   
   > but even a fully charged car battery is only 13.8v as far as I know and   
   > these days, I'm sure the direction of current flow and voltages are   
   > monitored very well by the computers. In the old days it was a bit of a   
   > black art just relying on the ability of the alternator or dynamo in the old   
   > bangers.   
   >  Normally the output will change due to engine speed, but  in alternators   
   > there is a voltage regulator inbuilt to keep the  thing pretty  nominal and   
   > of course the thing that then suffers is the charging rate, ie its going to   
   > be be slower when its not running very fast. I think if a battery dips below   
   > about 11v outside of starter transients, you have to charge it or get a new   
   > one. This  very accurate sensing these days can often mask a battery on its   
   > last legs though, as people tend to ignore  warnings if the car still works,   
   > then they leave it a couple of days and it won't start!   
   >   
   > Brian   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)