REFLECTOR: How to protect the battery bus

[Joe Ewen]

Hiroo,
Rather than a shunt you may want to consider a current sensor.  In my opinion there are several advantages to a Hall Effect Current Sensor.  There are no exposed electrical parts, in many cases it is lower cost than a shunt, it can withstand a much greater over current than a shunt, and it can be hooked to a single ended analog input rather than a differential input (single ended IO is cheaper than differential.)  The current sensor provides a voltage output rather than a current, so may not work properly with a discrete ammeter, but if you have a scalable voltage input (such as in a EFIS) then this would work very well.

http://www.ampsense.com/

Joe

  ----- Original Message ----- 
  From: Hiroo Umeno 
  To: reflectortvbforg 
  Sent: Friday, February 16, 2007 2:55 PM
  Subject: REFLECTOR: How to protect the battery bus


  Last weekend, I cranked the fickle Franklin one too many times.

   

  (Yes, I am still trying to find out why it simply will not run.  Long story.)

   

  On the third cranking, the voltage on the battery must have dropped sufficiently that the starter motor stopped turning the prop.  I probably left my thumb on the starter button a tad longer than I should have.

   

  The shunt blew and the whole electrical system went (except the backup battery system that ran the instruments (glad to know THAT works well).

   

  That got me thinking.  Shouldn't there be a CB or something protecting the starter line?  I've heard that the starter line is the only line that should NOT have a CB on.  Yet I've managed to fry the shunt.

   

  Any thoughts?

   

  Hiroo



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