garmin 450t

[+paul6921]

will a low battery cause the compass to turn in all directions? other geo-caches were found easily but the battery went low and it asked me to re- calibrate the compass which i only do when i change the batteries. it sent me 10feet in 1 direction and 10 feet in another direction. is this a result of a low battery? i do realize that you must be walking fast to get the compass to work accurately. anybody experience this with a 450 t or any other kind .thanks

[+GeekBoy.from.Illinois]

will a low battery cause the compass to turn in all directions? other geo-caches were found easily but the battery went low and it asked me to re- calibrate the compass which i only do when i change the batteries. it sent me 10feet in 1 direction and 10 feet in another direction. is this a result of a low battery? i do realize that you must be walking fast to get the compass to work accurately. anybody experience this with a 450 t or any other kind .thanks

My personal experience with the Oregon line is that the GPSr itself becomes less accurate when the batteries get too low. It may report a 12-16 foot accuracy, but it may really be off by over 30-40 feet. This also explains why my GPSr will consistently report a 8-9 foot accuracy when connected to external power in my car but goes to 12-16 feet when on battery. If the GPSr is less accurate, it may be bouncing you more and you are just thinking it's the compass that is being "flaky" due to the low batteries.

[+kwcahart]

Just guessing, but don't you also have to tell it what type battery you are using? If it has a diff type than you have it set to I think it could give you a problem.

[+dfx]

the compass will never turn wildly in all directions unless you're really close to GZ, in which case the GPS won't be much help anyway.

 

i've also never seen the oregon prompting me to recalibrate. it will bring up the recalibration dialog if you hold your finger on the compass rose for a while though. maybe that's what happened.

 

i can't say i noticed the GPS getting less accurate, but i never paid attention to that. i will now.

 

try using NiMH batteries if you don't already (and if you do, make sure you have the right battery type selected in the setup). if you need more than one pair, use identical ones. don't recalibrate the compass right after putting freshly charged ones in, rather use them for a few minutes and then calibrate the compass. with a bit of luck, you'll never have to recalibrate again. only keep in mind that the compass is likely off with totally fresh batteries, but that will wear off after a few minutes.

[+ecanderson]

The compass chip in these units is somewhat voltage sensitive. So yes, if you calibrate with a fresh set installed, your compass will start to behave strangely when the batteries start to become depleted. If you calibrate again at this point, it will help for a while, but at near total exhaustion they'll be off again, and when you install a fresh set of cells, the higher voltage can whack out your readings again.

 

FWIW: misidentifying the battery chemistry has no impact on this at all. That's just to give you a better "gas gauge" reading, nothing more.

 

My philosophy for NiMH on both my old eTrex Summit HC (2-axis) and Dakota 20 (3-axis, like yours) has been to calibrate with a fresh set after about 5 minutes use, and once I see 1/2 on the gauge, drop in new cells -- avoids the recalibration issue.

 

Since this last spring, I've been using NiZn cells. Unlike other battery chemistries, NiZn provides a very flat discharge profile -- the voltage changes very little from a fresh set to depletion. That avoids any compass calibration at all. The only downside is that there's very little warning when they're about do become depleted. The gas gauge is fat and happy, and the next time you look down, poof. So it's necessary to keep them charged or have a spare set in your pocket.

[+paul6921]

thanks to all i use alkaline batteries they went from 3 bars down to 1 bar in about 10 minutes of use i had the cells in there for while i probably held my thumb over the compass to long and brought up the recalabration page.i get a good signal even in a heavy canopy. the batteries these happened on were alkaline batteries i have sinced switched to nimh.i was surprised that the alkaline dropped so fast . i guess thats what caused the compass to send me in different directions.the 450t puts me within 2feet or less of the cache s i was surprised when it was off. again thanks to all.