Lightweight, basic GPS logger – Holux?

Lithium batteries have a slightly higher voltage

NiMH are slightly larger diameter

Lithium batteries is understandable, of course.

But it doesn't sound like you cannot use rechargeable AAs because they don't work, but because there might be a technical problem?

I think NiMH rechargeable batteries also have a little lower voltage. But a fully charged NiMH battery has a higher voltage than a mostly discharged Alkaline. NiMH can supply more current, so higher current devices like cameras are better with these.

It just depends on how they designed the device which batteries they'll run with.

You either have to listen to their recommendation or try it yourself.

I have been using the QStarz 1000XT since January, 2011. It has operated as reliably and accurately as I could have hoped.

There is nothing in the manual about operating temperature but I use it year-round; there is no problem using it in temperatures well below zero Celsius.

I have used the Bluetooth feature only once or twice. It is very slow compared to the USB feed. In any case I use the USB cable to charge the battery.

It uses rechargeable cell-phone style batteries. On one week backpack trips I take one spare battery and do not run out of power.

The mapping software that comes with the unit is rudimentary. If you want to superimpose track points onto a topo map it is a simple matter to use the QTravel software to export a .gpx file to hillmap.com.

It is not waterproof. I usually keep it in a plastic sandwich bag. Never a problem.

It needs a good view of the sky and works well at the top of a backpack or attached up high to a shoulder or other strap. It does not work well when placed into a Gossamer Gear Hipster (belly pack). The case does not completely enclose the GPS so you have to be creative/careful in attaching to a strap to prevent it from exiting the case.

There is no information display, merely a few status LEDs. It records your route and shows you where you have been when you load the saved information onto your computer.

It weighs 64.4 grams/2.27 ounces with battery on my scale. The case weighs 10.1 grams/0.35 ounces.

A quick search shows that they (or very similar models) are still available.

A few years ago I thought I had found the perfect minimalist GPS–the Wintec Easy Showily. A small LCD display showed latitude, longitude, elevation, and a few other bits of data. Unfortunately it died after about 1 1/2 years.

I have a gps that will not work with NiMH or NiCd batteries. With fully charged batteries, it lasts about 20 min, just until the battery voltage drops far enough that it thinks they are dead. It works great with alkaline, and very great with energizer ultimate lithium. It is made for 1.5 V, not 1.2V.

You don't mention which Holux model you have been looking at – I have been using the Holux m241 for a few years now, exclusively with lithium batteries (specifically, the Energizer Ultimate Lithium AA's) and so far its worked fine / hasn't melted. There is a lot of useful info on the OSM wiki at http://wiki.openstreetmap.org/wiki/Holux_M-241, well worth a read. I have also used it well below freezing without any issues.

I believe that the datum used by the m241 is WGS84 (see http://www.holux-uk.co.uk/holux-m-241-bluetooth-gps-logger.php?it=220). I generally pair it (vi bluetooth) with a smartphone running a "moving msp" app for navigation purposes, and also use it to record a track for geotagging photos. In the latter case, I used 3rd party software to download the data from the logger (BT747 software – see the OSM wiki above) and to Geotag the images (Geosetter software). Both of these software packages are free.

I have used the Lat/Long info in the logger window for a quick position fix without resorting to the smartphone, by dint of superimposing a Lat/Long grid on a digital version of the map I was using (using mapping software OKMap, which is donation-ware). Its surprisingly easy for a quick position fix, but does require that you print the map (and/or load the modified image into your smartphone "moving map" app). It also requires a georeferenced map.