Slow (very) Garmin GPS

Fascadale

Fascadale

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A recent post on the Liveaboard forum discussed Garmin GPS slow connections.

I have an oldish Garmin 128 GPS. It can take up to 20 minutes to discover its location.

My newer chartplotter gets a fix within seconds, so I have a good view of the sky, and the fact that the Garmin eventually works suggests the connection to its antenna is OK

In the other thread there was refernce to the Garmins internal battery.

Is it possible to change the internl battery and if so how ?

Thanks
 
Have you had the unit for any length of time or is it a 'new purchase' to you?

The reason I ask is it probably runs the same GPS engine that is used in the later Garmin 152 and if the unit has been moved more than 200 miles from the place where it was initially switched on and used, its internal 'memory' is looking at an incorrect part of the sky and will need to be 're-initialised'

I have just bought 12 new GPS 152's for an Atonis project and some were initilised on test in the States and others were initilaised in Asia. When first turned on in UK they did not want to work and I spent an hour or so trying to get them to aquire satellites. In the end I phoned Garmin UK.

Having phoned Garmin UK the technical problem was solved. [0808 238 0000 #3 and speak to either Nick Meadows or Craig]

FYI, on the Garmin 152 (and probably their GPS units) there is a boot-up procedure which will reset the unit back to factory default settings and you will have to re-initialised for your part of the world. /forums/images/graemlins/smile.gif

Hope this might help. /forums/images/graemlins/cool.gif
 
The 20 minutes acquisition time suggests a cold start, i.e. the receiver has lost the GPS almanac and has to re-acquire it from the satellites. So shortage of power between switch-ons is likely to be the cause. If the 128 handbook doesn't explain, send an email to Garmin via their website, they usually respond quite quickly.
 
Possibly at the risk of repeating what you already know. A poor signal from the aerial would increase lock in time and reduce accuracy due to not being able to use all the available satellites. A bad internal battery would allow the set to lose its memory of the constellation of the satellites so it would have to go through a full scan of the sky before it would be able to determine position.
If you are losing your waypoints, tracks etc when the set is off it's the battery. If you have low signal level on the satellites it's the aerial.
I can't tell you how to change the battery.
 
It may be worth leaving the unit powered for a good length of time (days!). Some GPS's self tune the internal timebase, which may have drifted on a unit that has not been used for a long time.
Otherwise, its a poor signal, possibly corrosion in the aerial unit. Try a different aerial.
 
We had a similar problem with a 128 after a winter layup, and used the 'reboot' procedure.

It did fail completely a few years later and Garmin replaced the unit for free. Later they replaced the aerial, also free!
 
Any message saying "memory battery low"?

If this happens the unit has lost its satellite almanac and needs to reacquire it before it can manage a fix. On my Garmin, leaving the unit powered up to boat's 12V supply for 24 hours or so is enough to reenergise the memory battery for a season.
 
Many thanks for all the swift replies

The unit is not new to me so it should know where it is

When it does get going it does give an accuracy of about 20ft

No Battery low message and it still lists waypoints on switch on

So it does sound as if it is an over winter battery issue, perhaps it will sort itself out with more usage.

(Would we enjoy boating were we not beset by these problems, and were it not for problems such as these how would we fill our Friday mornings?)
 
There's an internal lithium battery that stores memory when not in use. May be worth speaking to Garmin.

Are you still in that bay off Loch Sunart? If so, we could meet up sometime and see how our 128 manages with your connection, and vice versa. That may help eliminate cable or antenna issues. (EDIT: Oops, I'd misread; your new plotter uses same cable and antenna). Offer still stands.

PM me if you wish.
 
I inherited a very old Garmin GPS last year which would take ages to find it's position...........it turned out to be a Y2K problem (I said it was old).
What I did in the end was I found an old bit of software which Garmin had produced at the time which 'kicked' the GPS clock into the 21st Century and after this it downloaded an up to date almanac, problem solved.
If you think that this is the problem let me know and I'll try and find the info again.
 
To give you a comparison I took my Garmin GPS60 to Australia. Once I told that it was in a new location it found its exact position from scratch in less than 5 minutes. 20 minutes to find the position in a location close to where it was last used would indicate a problem.
 
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