Side LED markers and battery life

[mpisanek]

I'm sure that this has been discussed before but I was not able to locate the thread, so I'll ask again if that is all right?
 
I have just purchased a Europa with side LED markers.  I understand that the LEDs are powered by 4 9 volt batteries.
 
I have two questions.
 
1.  Aren't LEDs extremely low power consumers?
 
2.  What sort of life might I expect from a set of batteries, either alkaline or rechargeable?
 
Thanks.

[son_of_magni]

I imagine that the LEDs are wired in series.  Red LEDs have about a 1.5 volt forward drop so if you count the LEDs and multiply by 1.5 that's the minimum voltage you would need to just barely start turning them on.  So if you've got about a dozen LEDs, and with some margin, plus allowing for the voltage drooping as the batteries discharge, 4 would probably be the right number.
 
(Message edited by Son of Magni on September 12, 2005)