Do you want to use the device for navigation too? Or just be able to
record a continuous track without any stops and restarts?
If the former, get one of the car units (Garmin Nuvi or zumo for
example) that has a built in battery that takes over when the normal
power is lost. Also get a small sealed lead-acid 12V battery like this
one and it will get you though a full day of driving, maybe even two
days, and can be easily recharged overnight with small AC or DC charger.
http://www.batterymart.com/p-12v-2_9ah-sealed-lead-acid-battery.html
If you only want the track data one of the small GPS track loggers (no
display for navigation) will save the track data for several days on a
charge. something like this:
http://www.amazon.com/Canmore-GT-730FL-S-Rechargeable-Waypoints-Compatible/dp/B002UWKUZQ/ref=sr_1_13?ie=UTF8
Don't buy it as a "security store", they seem to grossly overprice them
because the folks that are fervently trying to catch their
spouses/kids/employees doing something wrong makes them will to pay
almost any price.
Most track logs in consumer handheld and automotive GPS receivers will
stop adding track points to a track when the movement ceases and resume
logging point when movement starts again. So if you look at a track
later you will have continuous track with a time gap where it did not
record stationary points.
If you stop the device it will normally end the track segment and start
a new one when it gets a fix again. If those both happen in the same
spot there might be a slight "jump" in the track where first segment
ended and the next began.
Jack
--
Jack Erbes in Ellsworth, Maine, USA (jacker at midmaine dot com)
(also receiving email at jackerbes at roadrunner dot com)