Garmin GPS 12 pretends batteries are dead?

[TheMaritimeMan]

Hi everyone,

A few weeks ago I got a mint-condition Garmin GPS 12CX on eBay. Besides having a dead memory battery (no surprise), it works perfect, and I've been having a lot of fun with it.

Today I went to use it, and when I turned it on, it only ran for a few seconds before it turned back off. I didn't remember the batteries being low last time I used it, but I thought nothing of it, and bought a pack of new batteries.

When I put the new batteries in it, it booted up, acquired a fix, and worked fine. Then about 2 minutes later, the battery meter all of a sudden fell from full to empty in about 10 seconds. Then I got the Low Battery warning, then it died.

Then it acted like before, running for only a few seconds upon boot-up before turning off. At one point, I turned it on, and it acted like it was running from a power adapter, with no battery meter present at all! It ran like that for about a minute before it shut off again.

I tested the new batteries, and they read ~1.6V each, like new batteries should. In-fact, I tested the old batteries too, and they are also just fine. I also tested the current draw of the GPS for the few seconds it would stay on, and it too is normal.

From there, I pressed Enter+Power to boot into the diagnostic mode. That's when I saw what appears to be causing this behavior. The GPS is able to display both battery voltage and external voltage (which normally should be ~6.0V and 0V, respectively), but for some reason, it's splitting the battery voltage between the two fields. For example, it may display a battery voltage of 2.3V and an external voltage of 3.7V before turning off (keep in mind that the GPS is not plugged into any external power source at all). This also explains why at one point it turned on and acted like it was plugged into an external source.

Why is my GPS 12CX acting like this all of a sudden? Like I said, it's in mint condition, (I personally doubt it was used more than once or twice before being put away for 10+ years), and outside of the memory battery being dead, it's been working absolutely perfect for the 3 weeks that I've owned it. I assume the memory battery won't charge because I've kept batteries in the GPS since I got it, and the memory battery error is still present. I wonder if the memory battery is in-fact charging, and it's reached a point between being dead and being usable that's confusing the GPS?

I hope this GPS hasn't simply died out of the blue. the GPS 12CX is a very rare model, and I've been looking for one for years.

Thanks for any thoughts,

Trent

[Alan Murphy]

Trent,

I am guessing that the memory backup battery has developed a short
circuit which may be temperature dependent. Once it warms up, the
short gets worse. Perhaps try cooling it in the fridge for a while
before you switch on to see, if that has any effect upon the time to
fail.

I have an old Garmin 45, bought in 1994, which still works. Over the
last 19 years I have always made sure that the batteries are fresh,
with plenty of volts, as I read that in the early days, if you let the
main batteries die, then the backup battery will gradually degrade.

The above is only a theory though, as I have good knowledge of the
behaviour you describe.

Hope that helps,

Alan

[TheMaritimeMan]

Alan,

Thanks for your response. Your theory definitely sounds plausible. I wonder how that works to make the GPS think a portion of the battery voltage is coming through the external power, though?

Anyway, I have an update on the issue. Today I received a power cord I bought for the GPS when I first got it. The GPS worked fine with it. Without batteries in, the voltages were as they should be; ~12V for external and 0V for batteries. With batteries in, however, the GPS still worked, but the battery voltage was still shared with the external. I would get something like 16V for external and 2V for battery.

However, I have had the GPS plugged into power and running all day, and I checked tonight, and the problem seems to have alleviated. For the past half hour I've had it beside me running solely on batteries, and it's working flawlessly, showing 6V for batteries and 0V for external. I'll keep it plugged into power overnight. I'm going away for the weekend and will be using the GPS solely on batteries, so I'll update again on how it's working.

Regarding your GPS 45, you may be interested to know that the 45 actually doesn't use a memory battery at all! The 45 and 40 actually use a capacitor to keep the memory alive for about an hour. Not as convenient for long-term storage of the unit, but excellent since there is no battery to worry about as these units are aging.

Thanks again,
Trent

On Thursday, August 15, 2013 11:06:23 AM UTC-3, Alan Murphy wrote:
> Trent,
>
>
>
> I am guessing that the memory backup battery has developed a short
>
> circuit which may be temperature dependent. Once it warms up, the
>
> short gets worse. Perhaps try cooling it in the fridge for a while
>
> before you switch on to see, if that has any effect upon the time to
>
> fail.
>
>
>
> I have an old Garmin 45, bought in 1994, which still works. Over the
>
> last 19 years I have always made sure that the batteries are fresh,
>
> with plenty of volts, as I read that in the early days, if you let the
>
> main batteries die, then the backup battery will gradually degrade.
>
>
>
> The above is only a theory though, as I have good knowledge of the
>
> behaviour you describe.
>
>
>
> Hope that helps,
>
>
>
> Alan
>
>
>
> On Tue, 13 Aug 2013 12:33:23 -0700 (PDT), TheMaritimeMan
>
>
>
>
>

[No Body]

In alt.satellite.gps, you wrote:
>
> Regarding your GPS 45, you may be interested to know that the 45 actually
> doesn't use a memory battery at all! The 45 and 40 actually use a capacitor
> to keep the memory alive for about an hour. Not as convenient for long-term
> storage of the unit, but excellent since there is no battery to worry about
> as these units are aging.

I had a couple of 45's years ago.. bought when they first came out... Built
like a brick outhouse!

The only two weaknesses I recall were the battery case door and the antenna
BNC.

Wasn't there a "service alert" on them a few years back about some sort of
DOW rollover problem with them?

Last I knew one of the 45's was still running as a gps clock, all these years
later.

I think the other one is in a drawer someplace.
~

[TheMaritimeMan]

Well, the night I posted my last response, the GPS ran for about an hour before it conked out again. I left it plugged in overnight, and the next day was about the same; It ran for about an hour before the power circuitry went haywire.

I now have a Panasonic VL1220 battery on the way. I'll be researching the proper type of silicone to reseal the case with and obtaining that, as well. It may be a long time before I actually get to fixing the unit, but if/when I do, I'll hopefully remember to report back here.

Thanks again,
Trent

[TheMaritimeMan]

Hi everyone,

It took a while, but I'm finally in the process of fixing this GPS. I currently have it opened up. (Cracking the case open was a very smooth process. :) ) I discovered something that rather goes against everything I learned in preparation to fix this thing. The memory battery is NOT a VL1220. In-fact, it's not even a rechargeable battery! It's a simple CR2032! Actually a BR2032, which is simply a high-temperature, low self-discharge version of the CR2032. I'll have to re-do my research and see if this battery is used across the 12 series, or if it's unique to the 12CX. It's good to know, though, as this means everybody who buys a used 12CX can now expect the memory battery to be dead, and expect it to be easily replaceable.

The battery has tabs soldered onto it. I could probably get a battery with similar tabs on eBay, but I figure I'll try my luck and see if I can de-solder the tabs from the old battery and solder them onto the new battery (which will be a CR2032).

Stay tuned!

Trent

[TheMaritimeMan]

Indeed, they were spot welded. I only managed to tear one off with my own hands, and I couldn't get it soldered onto the new battery (a CR2032), so that was out the window. It was a silly endeavour, anyway...!

Since I had already bought a VL1220, I decided to use that instead of putting $7 on a BR2032 or CR2032 with tabs. I did it purely as the cheap way out, and I might be sorry later since it's a much smaller battery that's meant to be recharged. At any rate, though, my GPS 12CX now has a good memory battery! I bought some RTV silicone, and with a little bit of mess, the case is back together, and it seems to hold just as well as the original factory seal. I don't know about (and won't test) its water resistance, but structurally it seems rock-solid.

Also, in response to the original reason I posted this thread, the weird voltage problem seems to have cleared. :) At least, it hasn't surfaced in the several hours I've run the unit. If that changes I'll report back.

I'm in the process of editing a (long and unprofessionally done) YouTube video documenting the entire process of replacing the memory battery. It's the first time a Garmin GPS memory battery change will be shown on video, so I hope it will help a lot of people who wish to try the same on their own unit. I will link the video here when its up.

Trent

[TheMaritimeMan]

Hi all, apologies for the delay. I actually got the video up shortly after my last post, but I completely forgot to post it here. Here it is:

https://www.youtube.com/watch?v=UwpybTtTfJo

I've gotten feedback from viewers who've opened up their units, with an interesting find - the 12XL and 12CX were sold with both the VL1220 and BR2032 for memory batteries. Possibly many other units sold before and during the turn of the century were, as well. My guess would be those units originally had the VL1220, and Garmin later moved them to the BR2032 in response to problems with the charging circuitry not fully charging the VL1220.

Trent

[L42E...@comcast.net]

Dear maritime: I have a Garmin GPS 12.
I took the batteries out some months ago to make sure that there was no leakage. I put fresh batteries in this morning. The message appeared "memory battery low".
And all way points have been lost 😥
I thought I read somewhere that if you put the new batteries in and leave it for three or four days, the lost waypoints will reappear.
Was this your experience?

[Stephen H. Fischer]

Hi,

My Garmin 12XL has an internal battery charged by the main main batteries.

The Internet said long ago to keep removable fresh batteries in the unit
when not is use for a long time. I thought that I had Lithium ones in but
alas only NiMh were found so the power on message with a set of Low Self
discharge Ni-MH said all memory was lost and stated that the memory battery
was low.

So I suspect that your waypoints are all lost like mine.

The Garmin 12XL is taking a long period to find where it it is in the world
as expected. A dead internal battery may prevent my Garmin 12XL from ever
finding where it is in the world.

The life time of the internal battery is ~ five years, Garmin at one time
would replace the internal battery, But I expect no longer.

I have moved on to the:

DeLorme
Earthmate PN-60
Rugged, Reliable GPS with Maps Included

Topo and Street Detail for U.S. and Canada

and before that the PN-20.

They have all maps included, even for where I camp, near to the wilderness
in the National Forests.

Bottom line, you made a bad decision, a set of batteries should be in the
12XL at all times.

SHF

<L42E...@comcast.net> wrote in message
news:6167cc86-2858-478d...@googlegroups.com...

[Stephen H. Fischer]

Hi,

I put charged batteries in my 12XL and surprise!

The internal battery took a charge. I have seen so many NiCd batteries fail
after five (5) years that after fifteen (15) years it was not expected.

If you want to keep your waypoints you need to transfer them to a computer
or keep charged main batteries in your 12, once the internal battery is
discharged they will be lost.

For extending the life of the internal battery it was stated decades ago
that you need to keep charged main batteries installed.

After some time a fix was done and then lost so my 12XL still works. I
actually see no reason to use it as I have two better GPS handhelds.

If the internal battery fails, you are stuck with a failed GPS. Opening the
case is hard, replacing the internal battery doable but closing the case
impossible!

Replacing a leaking main battery is easy, just check for leaks once a year.

SHF


<L42E...@comcast.net> wrote in message
news:6167cc86-2858-478d...@googlegroups.com...

[TheMaritimeMan]

Hi,

I thought I would post an update, two years later. When I replaced the dead BR2032 in my 12CX with a VL1220, it worked fine for about three weeks, and then the battery died. So evidently, units that shipped with the BR2032 have no facility to charge a rechargeable memory battery, if one is installed.

I put the unit away after that, and just brought it out a few days ago. Aside from the once again dead memory battery, it worked fine for a few hours, but now it's doing the weird thing again where it pretends the main batteries are dead and won't come on. If I leave it for a day or two, it will work again for a couple of hours before dropping the ball again.

I don't recall it ever doing this during the time that the VL1220 was charged and keeping the memory alive, so I'm still betting on and hoping that the dead memory battery is indeed what causes this.

I have purchased a tabbed BR2032 battery, and upon its arrival I shall open the unit again and install it. That will fix the memory battery issue once and for all (or for another decade, anyway), and I will report back on whether it cleared the weird voltage problem.

Trent

[TheMaritimeMan]

My replacement BR2032 arrived today, and I replaced it, and not only does the memory stay alive again, but the weird voltage problem is gone.

And so the question I asked here almost 3 years ago is answered - yes, a dead memory battery can cause a Garmin GPS to behave erratically, aside from just having the memory erase every time it is turned off.

Trent

[Heinrich Pfeifer]

thank you very much for your long-term report. I have an old 12XL from
1997 which I want to keep alive. No problem so far.

--

Heinrich
mail: new<at>pfei.eu

[TheMaritimeMan]

I have bad news all. While the GPS initially worked perfect after replacing the memory battery, it has since gone into such a downward spiral that it is now completely nonfunctional.

At first, after a few hours of use with the new memory battery, it started occasionally throwing the memory battery error again. But it would go away after a few seconds, and the memory always stayed intact.

A few days later, the power problem came back. Even with new batteries, the GPS would turn on for a few seconds, then turn back off, as if the batteries were dead. The memory still stayed intact though.

I left it for a few weeks, and now trying it today, it won't even turn on. I'm going to tear it open again, and see if anything's awry inside. The only thing I can think of is if one of the wires came off the memory battery and is shorting something out, but I'm not going to be surprised if everything's fine and the GPS has just kicked the bucket for no reason.

Trent

[TheMaritimeMan]

I've been inside the GPS, and found something disturbing. My solder job on the battery held fine, but the battery was discharged to 1.1V. Something is seriously wrong to have discharged the battery that far in a month.

I removed the battery - GPS still dead. I connected a fresh battery to the terminals - still dead. I connected external power to the data connector - still dead.

It appears this GPS has well and truly kicked the bucket, for no good reason. The only sign of life it gives is when you press the power button, it draws about 50 mA of current, from either the main batteries or the external power. I have no idea what could have happened to this. It went from working perfect to completely dead whilst sitting on a shelf.

[Hans-Georg Michna]

One not too rare cause is that an electrolytic capacitor has bit
the dust and corroded on the inside far enough to create a
shortcut.

https://en.wikiversity.org/wiki/Electrolytic_capacitor#Reliability_and_length_of_life

But this is just one guess. Another is that one of the chips has
soured, which happens due to diffusion of material inside the
chip.

Hans-Georg

[TheMaritimeMan]

There is indeed one lone electrolytic inside the unit, and I have been slightly suspicious of it. It would really surprise me if it's bad since the thing is only 16 years old, but I'll try removing I and see what happens. I got nothing to lose at this point.

[TheMaritimeMan]

I removed the capacitor - it tests perfect, and the GPS is still dead with it out of circuit.

I think I'm going to deem this a lost cause and sell it for parts, at a major loss to me. Based on the fact that this problem surfaced when I got the thing, and a dead memory battery shouldn't cause it anyway, I think this has a low-level electronic malfunction that was there from the beginning. I don't want to spend any more time on it.

Thanks to all who helped me. Maybe down the road I'll get another 12CX, and have better luck.

[Hans-Georg Michna]

I have given away my GPS 12 some time ago. I still have a Garmin
eMap and a Garmin GPSmap 76C. I don't use them any more. They
have been superseded by smartphones.

If mailing them to the US would not be so expensive, I could
probably sell them, as there is still interest in these Garmin
devices.

The GPSmap 76C floats, just barely. Smartphones rarely do. (:-)

Hans-Georg

[brian...@gmail.com]

Try using 'neutral cure' RTV sealant. In your YouTube video (which was good BTW) you mentioned the stuff you used smelled of vinegar, that means it isn't neutral cure. The fumes given off by non-neutral cure sealant are corrosive. The could have caused damage inside the unit.

Brian