Travelling with GPS is far comfortable then without it, the closer you know your unit the safer you feel... FEEL SAFER! |
|||
|
GPS Power Hacks
Without power, even the best GPS receiver is nothing more than
just an interesting box that does nothing. Given that a GPS unit
has to pick up signals from satellites that orbit the globe at an
altitude of 12,000 miles (19,200 km) and complete two rotations around the
Earth every day, it’s easy to see why there is a fair amount of power drain
by the antenna in order to pick up and decode the signal. Add to that the
power load of processing the data and displaying it, and you see that two
or four small batteries aren’t going to last too long under these conditions.
This chapter describes some power hacks you can do to your GPS to
improve battery life, and how to extend battery life by making use of
external sources.
GPS devices that contain a rechargeable Lithium-Ion battery are
appearing on the market now. While this is generally an advan-
tage, it can also be a disadvantage if it runs out in the field and
you don’t have access to a suitable charger.
GPS Power Needs
On the whole, battery lifetimes aren’t that bad, depending on what batteries
you use. Most GPS receivers use either AA or AAA batteries, but not all
AA or AAA batteries are created equal, as you’ll see in the following
sections.
For more information on batteries, a good website to visit is
http://michaelbluejay.com/batteries
Alkaline Batteries
A fresh set of alkaline AA batteries in a receiver such as the
basic Garmin eTrex will last approximately 22 hours, while the top of the
range eTrex (the Vista) will go through the same two AA batteries in about 12 hours.
Use poorer quality alkaline batteries and you will see a drop of a few hours in these times. If
you try using cheaper zinc-carbon batteries, you will see a huge decline in battery lifespan. A
set of AAs might last only a few hours.
In high-drain devices (which a GPS receiver most certainly is) cheap zinc-carbon batteries are a
false economy and offer very poor performance.
Compared to other types of batteries, alkaline batteries have greater availability, are reasonably
priced, and have a consistent lifespan (when using good brands). They often have a warranty
against leakage and damage, and are packaged with expiration dates (again, when using good
brands). However, they are costly, have a short lifespan, and are wasteful (not to mention envi-
ronmentally unsound).
Lithium Batteries
If you are willing to spend more and get a set of lithium AA batteries (not to be confused with
rechargeable ones), you will see a huge increase in battery life (two or
four times what you get from alkaline AA batteries). However, these batteries can cost two to
four times as much as good quality alkaline batteries.
Lithium batteries have an excellent lifespan in use, and a very long shelf-life. They also offer
excellent cold weather performance, and are lighter than alkaline or rechargeable batteries.
However, they’re generally not widely available; and as mentioned above, they are very expensive.
Rechargeable (NiMH) Batteries
By far, the best way to invest your money is on rechargeable batteries. Get the best possible
batteries, which means choosing nickel-metal hydride batteries (NiMH),
rather than the older and inferior nickel-cadmium (NiCd) batteries. In addition, choose the
batteries with the greatest capacity (over 2000 mAh, preferably 2300 mAh or greater). The rule
is that the greater the mAh (milliamp hour) capacity, the longer the batteries will last. These
batteries will initially be more costly than alkaline batteries — especially if you figure in the cost
of the charger too — but they can be recharged hundreds, if not thousands, of times.
Although some systems on the market claim to be able to recharge ordinary alkaline batteries, I
don’t recommend them. They are not recommended by battery makers; and not only do they
invalidate any warranty on the battery (such as the leakage warranty), but they also increase
the risk of the battery damaging your device. Play it safe and get proper rechargeable batteries
and chargers.
Compared to other types of batteries, rechargeables have a good lifespan in use, and can be
recharged repeatedly. They ’re environmentally friendly, and you can recharge them while you’re
on the move, using in-car chargers or solar chargers.
Some drawbacks to rechargeable batteries are that they are not widely available and they are
very costly. They generally have a shorter life than alkaline batteries, and they don’t handle cold
weather as well as alkaline or lithium batteries. They also require recharging before first use,
which can be inconvenient. Finally, some rechargeable batteries can be slightly smaller (in
length) than alkaline batteries, which can make the device cut out if subjected to shock or
vibration.
You should be sure to get two chargers. Get a fast charger for when you want batteries in a
hurry , and get a slower charger that you can use occasionally to recharge and
recondition your batteries. Alternating between a fast charger and a slow charger is good for
battery health and will guarantee you the best performance and lifespan from your batteries.
Make sure that your charger matches your batteries. Never use a charger that’s not designed
for the batteries you are charging
For best performance and safety, never mix battery types. That includes mixing old and new
batteries, different brands, and different types or capacities of rechargeable batteries. Mixing
batteries can result in poorer performance and reduced lifespan, and creates a real risk of batter-
ies exploding or rupturing.
A super battery-saving tip is to check the settings of your GPS. Look for an option or mode called
Battery Saver or Low Power Mode. Not all receivers have this setting, but if yours does, it means
that your GPS receiver consumes less power than normal, enabling it to last longer on a set of
batteries than it typically would. The disadvantage of this setting is a slight decrease in accuracy
because of the way in which the unit keeps a lock on the GPS satellites.
As for battery brands, there are plenty of good ones — Duracell, Energizer, Sanyo, Hama and
Ansmann are all of excellent quality and backed by good warranties. Avoid buying cheap “no
name" generic batteries, or batteries that are loose or out of blister packs — if these are DOA or
leak all over your device, you are unlikely to have any warranty to fall back on.
Another thing to remember is that some GPS receivers contain a small button cell, similar to a
watch backup battery (usually non-user replaceable), that is used to store some data in memory
in case the main batteries are depleted or removed. However, if you store your GPS for a long
period of time without batteries or with dead batteries, this can cause a drain of the backup
battery. If this is battery is run down, then the device may not work properly and will need
repairing. Therefore, when storing a GPS unit with this kind of backup battery, always be sure
to fit new (or recently recharged) batteries and check them regularly.
Never put a GPS receiver that contains old batteries into long-term storage, as this increases the
risk of damage from leaking batteries. Battery Do’s and Don’ts
The following guidelines will help you get the most from your batteries:
Recharge NiCd and NiMH batteries as soon as possible after discharge to maintain peak
performance.
Never store batteries loose in a bag or pocket, which increases the risk of a short circuit
that can result in fire or injury. Store batteries in a proper battery box or holder.
Store batteries at room temperature. There is no need to store batteries in a freezer or
refrigerator to maintain peak performance.
Never use batteries after their expiration date.
Never dispose of batteries in a fire, as this can result in an explosion and cause serious injury.
Extreme temperatures reduce battery life. Keep battery-powered devices away from
extreme heat or cold.
Take care that you insert batteries properly into your device. Some devices that use three
or more batteries might still function with one battery inserted incorrectly, but this can
cause battery damage that can potentially damage your device.
Dispose of used batteries responsibly.
Power Hacks
There is no doubt that having auxiliary power (in addition to the internal batteries) is handy
when out and about with your GPS. The easiest way to accomplish this is to carry a stash of
batteries and replace them as they run out. This method, while effective, is very expensive and
not very eco-friendly.
When in a vehicle, another option is to use a power cord that draws power from the automo-
tive 12-volt system via a cigarette lighter socket. Chapter 2 describes these kinds of cables and
how to make them.
But what about when you are on the move. How can you supply power to your GPS receiver
when walking, hiking, or geocaching. Carrying Your Own 12-Volt Power Supply
One thing that you can do is carry your own 12-volt power supply around with you. No, this
doesn’t mean having to lug a heavy car battery that can spill sulphuric acid all over the place!
Other options are available to you.
One thing you can do is buy a portable lead-acid battery designed for large flashlights. They
contain a cigarette lighter socket and often come with a case and belt loops. These batteries
usually have fuses. They come in a variety of sizes; generally, the
larger the battery the longer it lasts. The downside, however, is that the larger the battery,
the heavier the battery.
These packs will give you hours of additional battery time and the batteries can be recharged
when you get back to your vehicle by plugging them into the cigarette socket. Charging back
at base is via a charger that plugs into a mains power outlet.
However, you might have handy batteries suitable for this job lying about. If you have an old
PC uninterruptible power supply (UPS) unit lying around (the kind of thing that any self-
respecting geek would have!), these typically contain a battery similar to the battery packs that
you can buy for flashlights
Usually, you remove the battery through a hatch at the back of the UPS unit (remember to dis-
connect it from the mains power supply first). Once you have the battery out, you will need a
few things to complete the build:
Wire (automotive wire like the type used to wire in spot lamps is ideal)
A cigarette lighter socket
A fuse and fuse holder (such as those used in an automotive spotlight or in car stereo
parts; a 2A fuse will do just fine)
Connectors to fit the connectors on the battery (sizes will vary and depend on the battery)
A small car charger (to charge the battery when not in use)
Some sort of case for the battery (heavy-duty nylon or cordura( works just fine)
Assembly is easy. Wire the cigarette lighter socket to the battery, negative (–) to the frame of
the socket and positive (+) to the center post, remembering to add a fuse holder with the fuse
in the wire. Test the whole circuit with a multimeter before plugging a GPS power cord into
the socket.
These small lead-acid batteries are extremely handy auxiliary power packs and keep their
charge for a long time in storage (recharge them every three months when not in use). A
sticker on the side of the battery is ideal for keeping track of charge dates!
When you are outdoors, take great care when carrying a lead-acid battery. Any damage or
crack in the battery will leak dangerous, corrosive sulphuric acid.
If you want an alternative to lead-acid batteries, the following section describes how you can
make simple battery packs from ordinary batteries (or rechargeable batteries).
Battery Packs
Making a battery pack isn’t hard. All you need is a holder for the batteries and some way to
wire that to the GPS you use. The easiest way to wire it up is through the GPS connector.
Before continuing, however, first a little battery theory. If you take two AA batteries and put
them in a circuit end to end , the voltage will equal 1.5 volts plus 1.5 volts,
resulting in 3 volts.
This is called putting the batteries in series. However, if you place the batteries in parallel, that
is, take a wire and connect them positive to positive and take another wire and connect that
negative to negative (see F igure 3-9), and then measure the voltage across the two wires, you
will get a voltage measurement of 1.5 volts.
However, there is a side effect. The capacity of the batteries is increased. Therefore, if you take
four AAs and put them into two pairs of two in series and join the two pairs in parallel, the output voltage would still be 3 volts, but the capacity (or how long
the batteries would last) would be doubled.
As long as you have no more than two batteries in series, you can add a few sets in parallel to
get additional power from the system. This is true no matter what kind of battery you are deal-
ing with (although rechargeable batteries generally run at a lower voltage — about 1.2 volts —
than alkaline batteries do).
Remember that you aren’t limited to using AA batteries. The bigger the battery, the more
power you’ll get from it!
As you can see, a typical alkaline D-cell battery has approximately six to eight times the capac-
ity of a AA NiMH battery. The disadvantage is one of weight — twelve AAA batteries weigh
about the same as one D-cell, but the D-cell has 14 times the capacity.
Now that NiMH AA batteries are capable of capacities of 2500 mAh, they are getting close to
the capacities of their alkaline rivals. What You Need
This section describes what you need to build a battery pack. Remember that there are many
ways to build one and the final pack can be of any shape. The only important caveat is that you
don’t subject the GPS unit to too much voltage; if you stick to the normal battery voltages
you’ll be fine.
For example, a Garmin eTrex has two AA batteries and therefore runs at 3 volts, while a
Garmin GPS III+ runs on four AA batteries, providing the operating voltage of 6 volts.
Feeding more voltage through the GPS than it needs serves no purpose. If you feed it only what
it needs, you avoid wasting batteries (and carrying extra weight), and supplying wasted addi-
tional voltage.
Batteries
A good battery to use is the AA battery because it is quite light and easily available. If you want
greater capacity, then you might want to consider using D-cells, which have a far greater lifes-
pan but are heavier to carry. Battery Holder
Battery holders can be almost anything that can hold a battery. You can use a specific battery
box (available from electronic outlets), a box you have lying around your home or office that
you wire up, or something that you may already own that holds batteries.
A good example of something that already has a battery inside is a flashlight. Moreover, a
flashlight has the added advantage of having a ready-made switch (although you may want to
wire in a different switch because you might not want the flashlight on when you are running
your GPS from the batteries). Wiring and Connections
Figuring out the wiring and connections isn’t hard if you follow the instructions in Chapter 2.
All you need to do is hook up a connector suited to your GPS to a length of wire (covered in
Chapter 2) and solder that wire to the connection in your battery pack, paying special attention
to ensuring that you connect the positive and negative terminals correctly .
Load the holder with batteries and away you go!
This kind of battery pack gives you great flexibility. You can either keep it in your pocket and
use it only when needed or you can run your GPS from the battery pack and remove the pack
once it is spent and switch to the internal batteries.
Information on other types of power soruces coming soon... |
About US | © 2007 GPSReciever.net |