TT 720 Battery Life

tedkay · Posted: Mon Aug 20, 2007 1:43 pm Post subject:

The TT Techie may not have been such a numbnuts after all. He didn't actually mention memory effect - he simply said that if you leave the unit connected to the car charger all the time the battery will suffer.

This may well be due to heat rather than memory effect - the car charger is a more rapid charger than the desktop mount and it follows that the faster the charge the more heat is produced - and the unit is likely to be exposed to more heat on the car windscreen than it would be indoors anyway - the Li-Ion batteries are known to be susceptible to heat .... the doucument Oldboy referred to confirms this.

Trouble is of course that Sods Law says that if you leave it unconnected the damn thing will conk out at a crucial moment and you'll be back to yelling at the wife " Where the hell do I go here" and she'll shout back "Don't shout at me" by which time you've taken the wrong road and find yourself on a dual carriageway without an exit for about 20 miles !
Come to think of it maybe I can suffer a few glitches from the TT - I can shout at it and it doesn't start a huge domestic ... ! Wink

Andy_P · Posted: Sun Sep 02, 2007 11:05 pm Post subject:

tedkay · Posted: Mon Sep 03, 2007 6:55 am Post subject:

mikealder · Posted: Mon Sep 03, 2007 8:54 am Post subject:

Specs are there as a guide though (like rules, they are they begging to be broken), the actual current a device should draw is often different to the actual when measured, the worry is when you pull too much current through a connector it can melt under extreme conditions, two amps isn't a great deal but the pins are tiny.

The supplied charger is a great device for my Ameo though which consumes more power than the supplied charger can pass to it, if I use the TomTom charger on the unit it will charge whilst being used - this does show the TT charger output is higher than most in terms of current - Mike

Andy_P · Posted: Mon Sep 03, 2007 11:00 am Post subject:

tedkay · Posted: Mon Sep 03, 2007 12:17 pm Post subject:

xda · Posted: Mon Sep 03, 2007 12:58 pm Post subject:

Having just returned from a drive of 3hrs 50mins with my Go720 running on it's battery without the in car power lead connected I still don't have the low battery warning showing, it was still navigating correctly.
As the battery must be near exhausted i left it in the car for 15 mins with the in car power lead connected whilst unloading the car, after 15 mins it had started to get quite warm at the back, so unplugged it. Obviously the amount of current it was taking to charge the battery was significantly high enough to cause the battery to start heating up.
In normal use with it fully charged and on the in car power supply it stays cool for the duration of the journey.
I have let it cool down and it is now in it's desktop holder charging via it's USB cable for the last 30 mins and is still cold.
Draw your own conclusions from this but it is obvious that the in car power supply is capable of supplying a lot more current than the 500ma that a USB connection gives out.
_________________
Graham.
TT Go720, App:9.510(1234792.1) OS:842337
GPS: V1.20, Boot: 5.5279, Home: V2.9.5.3093
Map: Europe V910.4892
Map: Europe_Truck V870.3421, Kingston 8GB SD
Nokia 925 Windows 8

Andy_P · Posted: Mon Sep 03, 2007 1:06 pm Post subject:

My point was (and I' don't have specific figures for this unit):

Current drawn on the 12Volt side of the unit (which is where the 2 Amp fuse is) will not be the same as current delivered at the 5Volt output.

I'm not saying the Car charger ISN'T faster than the Home Dock, just that I've not seen it stated anywhere. Has anyone?

For the technically minded,

http://www.zetex.com/3.0/appnotes/apps/an40.pdf gives a good description of the complexity.

tedkay · Posted: Mon Sep 03, 2007 1:27 pm Post subject:

Andy_P · Posted: Mon Sep 03, 2007 1:55 pm Post subject:

navigator8 · Occasional Visitor Joined: Sep 08, 2007 Posts: 1

there is a difference between what the pc usb port can supply and the car charger. the pc usb port (or a hub) is limited to 500ma usually (sometimes 100mA), while the charger is limited to 2amps. that's why it is necessary to switch off the unit when you want to charge it from your pc.
your sat nav will recognise when it's connected to a charger and then allow battery to charge faster. now, even if your charger can supply 2amps, the battery will take what it needs (usually 0.6amps max).
when the battery is empty (after a few hours of drive) and you connect it to your charger, it will take the max charge current for about 1-2hours, so it's good to switch off your unit if you are not using it, to avoid too much heat inside.

cejsmith · Posted: Sun Sep 09, 2007 10:21 am Post subject:

FYI

I've had a email from TOTOm say that as my battery life is just over and hour. I should either return it to the shop or to TOMTOM for a replacement.

They say you should get at least 3 to 4 hours. So hopefully a new one will be better. Does any one know how you trnasfer tomtom plus from one 720 to another ?

Andy_P · Posted: Sun Sep 09, 2007 8:46 pm Post subject:

With difficulty....

Several people recently have found that updating to a new model, or even swapping unnits that are faulty, has meant umpteen calls to customer service, multiple faxes of proof of purchase etc. Basically, they want you to have a brand new account (requiring a new email address) for a new unit, doing it any other way or transferring an existing "Plus" account to a new unit, seems to tax them to the limit. It's certainly beyond the 1st level "techs" of customer service.

technik · Posted: Sun Sep 09, 2007 10:17 pm Post subject:

Was it worth swapping for a replacement 720. ?

Do you now get 4 hours when only 2hours max before. ?

I don't think it's worth swapping unless there is an improvement in battery life.

I always use external power anyway, but if that fails then the 720 is not going to get me to my 4 hour destination.

On the box it says '5 hours operation' but does not say battery life, or is that the time when you start realising the 720 has many problems. ?

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