For what it is worth my 2 garmin 45 XL GPS's sat for 3 months on one of 
them and 14 months on the other they did not lose any of their way 
points or other stored data.  Three were not batteries in either unit.

Bob

John Nall wrote:

>Howard Winter wrote:
>  
>
>>>Actually, not necessarily!  My brother has a boat and I did some rewiring for him last year.  As you say there 
>>>      
>>>
>>are battery switches that allow the two batteries to be used together, independantly, or not at all, but there 
>>is also a small "always on" feed which takes power from the "Domestic" battery (the one that isn't used to 
>>start the engine). 
>>    
>>
>.
>Obviously I do not know about the battery switch on your brother's boat, 
>but the battery switch on my own boat, as well as all the others that I 
>know of, will disconnect the "panel feed" wire when the switch position 
>is turned to OFF.  As you say, this "panel feed" wire normally goes to 
>the bus from which all the accessories such as GPS, radio, etc., derive 
>their power.  Whereas the main wire (or, more accurately, cable) goes to 
>the starter for the engine.  But I know for an absolute fact that my 
>battery switch will disconnect everything when turned to the OFF position.
>.
>
>  
>
>>>The boat-repairer may have removed the battery connections so the GPS lost its waypoints, and may have failed 
>>>      
>>>
>>to reconnect the "always on" wire, which will be a small one, easily missed when connecting the huge main 
>>battery cable.  Get your friend to look at the batteries, and see if there's a small unconnected wire hanging 
>>around nearby, possibly with an inline fuse in it.
>>  
>>    
>>
>.
>Had the panel feed wire not been connected, then the GPS unit would not 
>have powered on.  So I don't think that is the answer.  One person 
>suggested the possibility of an intermittent power connection such that 
>the internal software for the unit might not have functioned correctly.  
>Although this does not make complete sense to me, it nonetheless makes 
>more sense than any of the other educated guesses.  :-)
>.
>
>  
>
>>>All the talk of bad antenna connections and such is irrelevant - no form of connection to an antenna would 
>>>      
>>>
>>affect the stored data, only its ability to find out where it is at the moment.
>>  
>>    
>>
>.
>I agree.. 
>.
>John
>
>
>  
>
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