Garmin Geko201 and rechargeables?!

[TLS76]

Hi there!

 

As i were recently buying AAA sized batteries on a weekly basis, i finally ordered a nice set of NiMH rechargeables (750mAh) and run into a funny software problem of the Geko201.

 

In the Setup->System menu of the unit, you can switch the battery type from Alkaline to NiMH. Ok so far so good. This makes sense, as an Alkaline battery has a nominal voltage of 1.5V, while rechargeables mostly have 1.2V and you should get a reasonable battery-voltage-bar display with useing both types.

 

Ok, and now the odd thing: If i use the NiMH set for 2hours, the battery bars drop down very quickly, with the setup switched to NiMH, but if i switch the setup back to Alkaline, i immdediately gain two bars in the battery display.

 

Could it be, that Garmin mixed up the labels and the Alkaline setup is in reality the NiMH setup and vice versa?!

 

I´m just wondering...

 

Cheers

Tobias

 

P.S.: Software version is V2.20

[+quakemap]

Kind of strange that you mentioned 750MAh - most NiMH batteries now fall into 1600-1850MAh range, and 2200MAh are out (http://www.thomas-distributing.com)

There is a wealth of info on batteries in the forums, you can use Find tab, search for "NiMH"

 

Here is an interesting FAQ: http://www.greenbatteries.com/documents/Battery_FAQ.htm

 

Happy trails,

 

http://www.quakemap.com - redefining Easy...

[+quakemap]

Just wanted to mention that alkaline batteries drop voltage in time proportionally to the used capacity, while NiCd and NiMH hold 1.2 volt pretty steady till the last point, and then die rapidly. I don't know if this explains your Geko 201 behavior.

 

http://www.quakemap.com - redefining Easy...

[SergZak]

quote:

---

Originally posted by quakemap.com:

Kind of strange that you mentioned 750MAh - most NiMH batteries now fall into 1600-1850MAh range, and 2200MAh are

---

 

Tobias was talking about AAA batteries and not AA's. Highest AAA mAh rating I've seen last time I checked was 750-800.

[TLS76]

@quakemap.com:

SergZak is right. I was talking about the even smaller AAA sized batteries. Geko units all use AAA size, while the eTrex series uses AA.

 

@all:

However i was just wondering, if anybody else has seen that strange behaviour. Personally i will stick to useing the "Alkaline" setup for my NiMHs. The battery bar drops slowly and linear in this setting and if i measure the voltage, when the unit reports "Battery low" it is around 1,15V per cell. That also seems to be fine.

 

Would be worth to do the countercheck and use the NiMH setup for Alkaline batteries one time. :-)

 

Cheers

Tobias

[+Mr. Black Cat]

I won't be changing my Geko 201's settings from "Alkaline" again. Several weeks ago I put in NiMH's and changed the battery setting, and the unit died; it wouldn't wake up with Alkalines or a power cord.

 

Garmin RMA'ed it; said they had to do a "Master Reset" and now it works fine...

[Tahoe Skier5000]

I have this same sort of issue with my Vista. (though i really dont care)

 

I'll put freshly charged NiMH batteries in, and the battery guage is full for about 30 minutes of use, then it drops rapidly (over 1 hour) to less than half power. Once it gets to this point, it slowly decreases to empty over about a 8 hour period of use.

 

This all has to do with the nature of rechargeables. Since their voltage is much less than alkalines, they tend to put out power very steadily and then drop off rapidly and suddenly when the juice is running out out.

 

-----------------------------------------------------------

Garmin Vista

Using Opera 7.1

[+CharlieP]

Alkaline batteries discharge linearly, starting at 1.5 volts and going dead at about 0.9 volts. This makes it very easy to monitor remaining capacity by using the voltage, e.g., if the voltage under load is 1.2 volts, the batteries are about half gone. NiMH batteries have a much different discharge voltage curve, starting at about 1.3 volts, dropping to about 1.2 volts within a few minutes of operation, discharging slowly from 1.2 down to 1.1 volts, and then going dead. Because the voltage is in the very small 1.1 to 1.2 volt range for most of the cycle, it is difficult to accurately monitor remaining capacity of NiMH cells by measuring voltage. But the main problem with using an alkaline gauge for NiMH cells is that the NiMH will rapidly go dead when the gauge shows 1/3 capacity remaining.

 

FWIW,

CharlieP

[+TheDenvernators]

So my question, how long have you gotten with the nimh batts in the geko?

I've considered this myself, since the one major fallback to this device is the AAA batteries.

Thanks!

[JoeHKill]

Well I would not call it a "fall back" you have 12 hrs. of battery life, and it is not that hard to fit 2 extra AAA batteries into your pocket or back pack.

 

And it sounds to me that you should contact garmen at www.garmen.com and ask them about the isue.

[+TheDenvernators]

Well, compared to the life it would get with AA, I considered it a fallback. But I do love the 201, and have made it my fav amongst the two I own. (The other being a venture).

I'm sure Garmin thought of this long before I complained, so my email to them shall remain unsent.