Nuvi 700 series battery

Garmin claims that a fully charged battery will last between 3 and 7
hours. With my nuvi 750, after a recharge via the usb port on a
computer I get the "LOW BATTERY" warning after 70 minutes. Brightness
is set to 50%. What I did to test it was to charge the battery for
about 5 hours (the bars show full charge). I then put the unit outside
with the power on and with a clear view of the sky.

I'm wondering what others are experiencing.

Due to experience with poor sensitivity (in comparison to my 76csx)
and the fact that it won't run for very long I'm ready to return it.
Either claimns are exagerated or I have a bad unit.

Thanks,
Bob

Hi,

I have no experiences with the Nuvi, but to me it seems like that the " 5
hours USB charging " may not be enough or not too efficient, evn if the
battery shows it is full. I have several electronic devices from GPS to MP3
players and some of them show "fully charged" 1 hour after I plug them in,
but aren't really FULLY charged. Try to charging it overnight with a regular
AC or Car charger, then turn the unit on and let the battery run down
completely. Recharge again overnight then drain it completely
again.........repead this procedure for at least 3 - 5 times. Many batteries
only reach their full capacity after several good charges and discharges.

I have an MP3 player which got on the first charge 19 hours
playtime..........now after at least 5 charge/discharges I get 27 hours out
of it !

Just try it, but there is still the possibility that you have a bad battery.

Hope this helps.

Cheers,

jce

I haven't really tested this but I know that when I first got the unit (750)
I charged it fully and then placed it out on my deck on it's battery power
for at least two hours and I'm pretty sure the bars didn't go down over half
way. After trying what JCE suggested, if you can't get more than 70 minutes
on a charge something is wrong with it.

The real issue is that the USB power is not design to be a charger.

Electronics 101

Power supplies despite what make or model shape is either be a voltage or
current source.

A regular box type power supply is simply designed to be a voltage source
meaning that the current is limited to what the final stages of the power
supplies make it. Look at the voltage regulator LM-317T.

Battery charges are different in design where voltage is not the issue but
the current. Batteries requires more current for charging purposes as the
battery (the load) varies its resistance during charging.

A USB power source is simply a small amount of current to simply supply
small items hence why often you require two connectors (which is parralled
connected for larger current not voltage) to have power running into it.

In a normal charging cycle when a battery reaches it capacity where the
power supply can no longer supply further, the indicators will provide a
false positive and you will see the item (in your case the GPS) fully
charged. As you use it, the load depreciates dramitically the results shows
the problems to what you are seeking.

Simple solution - There is none yet. USB was never designed to be a charger
showever some small electronic devices may work out. Not a good idea.

Use a proper power source like the charger that is going through your
vehicle.

Main Charging - Better check with Garmin however untried and also I will not
take responsibility should anything goes wrong is that you could use the
mains charger for the Motorola mobile phone because Motorols charges their
mobiles via the USB plug. Their power supplies are current source types.

Good Luck

LDL wrote:

Personally, I would be leery of charing my expensive GPS in the car
because of the risk of current spikes depending on engine speeds and
other factors. I have damaged many cell phones over the years charging
and driving in car.


The AC power adapter is an optional accessory from Garmin. Of course,
Garmin charges a premium for it. I wonder if the aftermarket ones are
equally good and safe. I guess one would need the specific specs to
know which Generic AC adapter is compatible with a Nuvi.