Finding a wall charger with correct charging specs...


Joined
Jun 3, 2007
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157
Location
Oregon, USA
Finding a non-TomTom wall charger with correct charging specs...

eBay seems to have a number of low-priced chargers for TomTom models. However, when I've inquired about the voltage and amperage of some of those devices, the sellers will refuse to divulge what they are peddling, or the advertised specs are way off what TomTom's own "Home" charger provides.

TomTom's supply provides a full 2A of regulated current. Most of the after-market supplys I've been able to locate are averaging about 400mA - 800mA...well below TomTom's spec.

What I've discovered is that the low-amperage supply fails to deliver a full charge to a partially discharged TomTom in less than 4-hours. TomTom recommends not leaving your inactive device on recharge for longer than 4-hours...once a week. It's all about the LiON battery charging spec, and TomTom has already seen a number of premature warranty returns...due to overcharging.

Does anyone know of a "Home" type wall-wart, mini-USB charger that precisely meets TomTom's specs...and is a FABULOUS BARGAIN?
;)
 
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Joined
Nov 25, 2007
Messages
286
Location
Chicagoland
TomTom Model(s)
ONE 3rd Edition
eBay seems to have a number of low-priced chargers for TomTom models. However, when I've inquired about the voltage and amperage of some of those devices, the sellers will refuse to divulge what they are peddling, or the advertised specs are way off what TomTom's own "Home" charger provides.

TomTom's supply provides a full 2A of regulated current. Most of the after-market supplys I've been able to locate are averaging about 400mA - 800mA...well below TomTom's spec.

What I've discovered is that the low-amperage supply fails to deliver a full charge to a partially discharged TomTom in less than 4-hours. TomTom recommends not leaving your inactive device on recharge for longer than 4-hours...once a week. It's all about the LiON battery charging spec, and TomTom has already seen a number of premature warranty returns...due to overcharging.

Does anyone know of a "Home" type wall-wart, mini-USB charger that precisely meets TomTom's specs...and is a FABULOUS BARGAIN?
;)
To know absolutely sure what minimum size charger will work, you'd need to know the specs of the battery in the device. As long as the charger can provide a stable 5 volts DC, it won't matter what the Current rating is as long as it exceeds what the fully drained battery will draw.

Current is "pulled" by the device consuming the power... it's not "pushed" by the charger. If the device wants to draw exactly 800 mA, then that's exactly what the charger will supply- no matter what its rating. If the specs of the charger can't meet 800 mA, it will still provide 800 mA for a short time before it overheats and/or burns out. If the specs of the charger exceed the 800 mA, then you'll be fine.

The TomTom charger is designed with an Amperage rating to exceed the amount of current your TomTom will draw. Since we know very little about the TomTom battery, we don't really know how much their 2 Amp rating exceeds the maximum current draw.

(I'm an Electrical Engineer.)

Do you have an iPod wall charger? It's rated 1 Amp @ 5 volts on the output. It has a standard USB connector so you'd just use your TomTom USB cable.

As far as reading Current ratings: Amperage ratings are only the MAX the charger can safely supply... it's not necessarily the same amount the device will require. Current (Amps) will fluctuate greatly depending on the demand. A fully drained battery will draw more current than one that's nearly charged. So even though TomTom's charger is rated to supply 2 Amps max, that's certainly more than the TomTom battery will require during a full re-charge.

Unfortunately I could not find specific details (mAh) on TomTom's batteries but I did find that the Magellan Maestro contains a 1200 mAh rated battery with a 3-hour capacity. Based on that information, the Magellan's battery will only draw an average of 600 mA over a two hour recharge cycle.

I can't imagine the size difference between TomTom's and Magellan's batteries would be very significant for the purpose of this discussion.

Side-note: The TomTom's car charger contains a 2 Amp fuse which is further indication that the device will not ever draw a full two Amps at any point in the charge cycle. If it did, or even came close, you'd be blowing those fuses all the time.

Your assumption that you must find a charger rated at 2 Amp output is playing it safe and that makes it a very good assumption but I believe that a charger with a lower rating could work just as well.

You should have no problem with an iPod charger if you have one. If you don't happen to have one, then it's not a very economical solution at $30.
 
Joined
Mar 20, 2007
Messages
39
Location
Long Island, NY
TomTom Model(s)
TomTom One
The good chargers provided regulated outputs, usually switching power supplys, that will provide a constant 5VDC needed by the TomTom. These usually will work from 115-220VAC. The cheaper ones use an unregulated supply where the output voltage varies with load. As far as the charging time goes, if the TomTom circuit is designed properly, it will take longer with a supply that is less than 1 amp in rating but the batteries will eventually charge. A good charger circuit should reduce the charging current to the batteries once they are charged to reduce the possibility of damaging the batteries. I would hope that TomTom used this type of circuit.
 
Joined
Nov 25, 2007
Messages
286
Location
Chicagoland
TomTom Model(s)
ONE 3rd Edition
The good chargers provided regulated outputs, usually switching power supplys, that will provide a constant 5VDC needed by the TomTom. These usually will work from 115-220VAC. The cheaper ones use an unregulated supply where the output voltage varies with load. As far as the charging time goes, if the TomTom circuit is designed properly, it will take longer with a supply that is less than 1 amp in rating but the batteries will eventually charge.
Those are excellent points.

Unfortunately, he probably won't be getting a higher quality charger for "the fabulous bargain".

Unless he has something of quality like the iPod wall charger already lying around, he should probably just bite the bullet and invest in a good one.

A good charger circuit should reduce the charging current to the batteries once they are charged to reduce the possibility of damaging the batteries. I would hope that TomTom used this type of circuit.
Yes it should. TomTom has already stated either through FAQ's or email that you can leave your unit on the charger indefinitely... the TomTom circuit will stop charging batteries when the cycle is complete. It will also stop charging when the temperature is out of spec. Just to be perfectly clear to anyone else reading this, the charging circuit is in the TomTom... the chargers are just supplying clean 5 volts DC at any drawn current up to the rated Amperage.
 
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Joined
Jul 8, 2007
Messages
128
Location
New London, NH
TomTom Model(s)
ONE V2
^^^
the charging circuit is in the TomTom... the chargers are just supplying clean 5 volts DC at any drawn current up to the rated Amperage.

Bolded for emphasis!

Any power supply (I prefer to call them power supplies rather than chargers) that meets the USB specs should work fine, be it wall wart or vehicular. You can find these dirt cheap on eBay or at www.geeks.com.
 

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