I got one with 2.3/2.6 FW in it. Last weekend I dropped in a fully charged 2300 mAh NiMh''s, and went to hide a cache. You know what!? It went completely DEAD in 55 minutes! All this with backlite set as "0", no beeps, occasionally switching between the windows and configs. This turned me crazy....
Assuming my NiMh's were not 100% OK, - I took them from my DSLR camera, and these are may be 5 month old...I decided to make some lab measurements.
Instead of AA's , connected my Colorado-300 to lab grade DC power supply, with digital voltage and current meters.
Made the measurements in all 3 modes, (Alkaline, Li-Ion, NiMH), reducing the voltage on the regulated lab power supply from 3.0V down to.... 2.1V ( this 2.1 was my hope !).
Here is my readings:
Alkaline
@ 2.55 V - backlite goes off, warning pops-up, only one RED bar left on Colorado300's battery meter
@ 2.29 V - GPS unit goes totally OFF
NiMh
@ 2.57 V - backlite goes off, warning pops -up, only one RED bar left on Colorado300's battery meter
@ 2.31 V - GPS unit goes totally OFF
LiIon
@ 2.60 V - backlite goes off, warning pops -up, only one RED bar left on Colorado300's battery meter
@ 2.32 V - GPS unit goes totally OFF
This makes me think - does the "Alkaline-NiMh-LiIon" setting changes anything at all ???
The reading differences between these 3 cases are so small - it could easy be a variation of the voltage reduction rate (slope) (I was reducing the voltage at the rate of 0.01V per second, i.e 0.1V drop in ~10sec.. Done manually, and could be that rotation of the voltage control was not extremely smooth)
In any case, this makes me wandering of one think - how much the NiMh's can be used at all ?
If at 2.55V already the warmig pops up, and the backlite goes down? WTF ???
IF the operationall voltage range on COLORADO could be extended from 2.32V down to ~2.15V - it would add many many hours of work.
IMHO, 1.16V is NOT the level, where NiMh cell could be called a completely exhausted
As we all know, 1.2V is a "Nominal Cell Voltage", and it can we discharged down to 1.05-1.1V without any permanent damage.
Was the Garmin's "FIX" in released 2.3/2.6 firmware only a simple mod, where "Alkaline-NiMh-LiIOn" setting was simply disabled?? And now it always use "NiMh level" , regardless of what you see on your Colorado's display?
I can understand such "fix" could improved the "lifetime of Alkalines", as most likely - the "low voltage triger level" was even higher before, then is the present 2.55V
Final note:
I can't remember any other case in my life, when a new product has caused so much dissapointment
(not only battery issue, but all that other things, what we read here on this forum dozens of times)