Handheld GPS

Has it been shelved for appreciable length of time ?

Suggest connect via power to a car battery etc. - leave it looking at sky and let it update / reload its almanac data etc.

Common problem with GPS when not used is to lose data and then have to spend anything like 12 - 24 hrs to get it all on-board again .... it may also have a duff memory retention battery ... a button cell inside ...
 
I have a Magellan handheld. A year or so ago I was ready to chuck it away and get another as it was hopeless at finding satellites and keeping locked on. Eventually I contacted Magellan in US via email and nice bloke told me to initialise by wiping everything off, leaving a few minutes, then turning on and being VERY PATIENT for as long as it took - and it might take several hours - for it to 'find itself' again. I was sceptical, but it worked! Now it finds satellites very quickly, stays locked on and the battery power lasts longer too.
 
I have a Garmin 45, about 12 years old(?). It was misbehaving. eg. failing to pick up satellites and showing me where I wasn't.
I took out the batteries and left it for a few days before fitting fresh batteries and re-initialising it. It took HOURS to finally establish where it was and update itself (firmware? Almanac?).
It now works great; powering up and on-line in just a few minutes.
 
I have a n*vman in the car which is like that - the minute there is a cloud in the sky it loses its fix. The first fix can take hours sometimes!
 
I too have a Lowrance iFinder Go and have noticed that it seems really fussy about the battery voltage.

I have been running it off NiMh rechargables, but even when it shows the batteries as 2/3 full it won't get a fix. Putting in a freshly charged set of batteries seems to get it going again.
I'm planning on switching to Duracells next year, to see if they give longer service.
 
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Oh dear. I only get to sail every 3 weeks at most. Does that mean that I have to let the GPS 'find itself' for 24hrs before I use it every time?

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Doubt it. I don't think mine likes being used in one location, then flown several hundred miles to be used in another. It gets confused.
 
Use ...

I would guess that maybe your internal button battery may be on its way out ... they can be changed.


But anyway ... all you have to do is stick it the window every now and again and switch it on - leave it for a day ... My old 1980's Magellan Meridien is a right B***** for this ... but sorts itself once it's had its switch on day .... which happens maybe 2x a year !!
Do you have a spare car battery anywhere ? An old one with a duff cell is good enough ... I have one under my desk right here at home ... I then have my GPS siting in the window powered from that ... allows me to play with cahrting prog's etc. as its also connected to PC. Saves on AA's etc. and gives you literally endless power to the HH .... That would sort you nicely.

But every 3 weeks shouldn't be a problem ??
 
Are you taking the batteries out when it is not in use? If you are this may be your problem.

I have a Garmin Map76, I believe it has some options which come up when it has difficulty locking on to satellites one is an option to be selected when booting up for "Stored without Batteries" another is I believe "New Location".

When I left it without batteries for a couple of months I had to use this option, it took a long while to boot up but has been fine since.

My GPS moves between boat (Winderemere) and home (Cheshire) and does not have any much difficulty working out where it is.

If you are only sailing every 2 to 3 weeks and taking batteries out in between it may be the internal battery never has any chance to charge properly.

David
 
I have a feeling that my Garmin 12XL (poss representative of all Garmins??) has the answer. It has a rechargable cell with a poor hold-up time. I operate it without it's own batteries, so it gets plugged in to boat power for actual use. If I dont go out for a long time, it comes up with a message, wording I cant exactly remember, but saying the data memory is low.. and then takes ages to relocate, with other messages asking which method to use for location. Then it is OK until next time I leave it for a significant interval. Not the fault of the GPS unit, just a battery problem. /forums/images/graemlins/smirk.gif
 
Slow first fix time :
This is due to the need to pick up at least one satellite for 15 minutes solid in order to get the almanac data which gets transmitted every 15 minutes (what satellites with which code number are where in orbit) and also the ephemeris data which is transmitted more often (how much they have drifted from the almanac position) when cold starting in the worst case.

Normally you only need to wait about a minute for ephemeris data on older recievers like the Garmin 45, hence these take about a minute from switch on to get a position fix.

I was once present when the owner of a non-functional old Garmin 40 was being persuaded to buy a new GPS in a chandlery. I was outside with his GPS. Just as the deal was concluded I rushed in with a position showing on the old GPS. The sale had taken about a quarter of an hour ...

I have also run a set of batteries flat on a Garmin 45 without getting a position fix because it never saw a satellite in the sky for long enough in my enclosed back garden.

Normally a GPS contains a valid almanac stored when it was last used , they do have an expiry time in the region of weeks AFAIR. When the backup battery fails this data gets lost giving the symptom of needing up to 15 minutes for the first fix.

Another thing that is stored is temperature compensation data. Losing this can increase the time taken to find satellites as it introduces more uncertainty in the operation of the GPS.


More modern GPS recievers employ clever tricks based on empirical and theoretical knowledge derived from years of experience of operation of GPS - things like yesterdays ephemeris data is almost certainly valid to start off with today so dont wait once you have tracked three or more satellites to give a position fix.

That brings the time from switch on to fix down to less than a second.
 
I use a Garmin 12 as a back up and whilst I sail every couple of weeks, I often don't turn it on as many's the time it is just a river trip and thus pilotage only.

When I do turn it on 3 or 4 times a season it finds it's position quickly and accurately
 
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