TomTom Bicycle Battery Pack

Discussion in 'Technical Support' started by sparky672, Nov 26, 2007.

  1. sparky672

    sparky672

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    The manual talks about an approximate battery life of 2 hours per charge.

    If I set the display to always go OFF, how much could I expect battery life to improve.

    I completely understand there are dozens of other variables that effect battery drain and my "milage may vary".

    But what's a good ballpark approximation? 20%, 50%, double, more?

    I'm trying to gauge how useful this device will be on long bike trips.

    Thank-you.
     
    Last edited: Nov 28, 2007
    sparky672, Nov 26, 2007
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  2. sparky672

    flyer1024

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    Not very useful I'm afraid if you have no external power source. My unit is just over a month old and on a fully charged battery I see only about one hour.....nowhere near two hours.

    undoubtedly that will get worse over time. One of the things that batteries don't like is heat and these units sitting on a windshield in the sun are always running too hot. also lithium batteries don't like deep discharge....fastest way to kill one is discharge it completely a few times....I'm not sure what the low battery cut off is in these units, but that in itself may be contributing to the reported short battery life.

    also not sure whether there is a cut off on the charging circuit...overcharging is also a battery killer. hopefully the unit is smart enough to prevent over charge and over discharge.

    anyone have any information on that?
     
    flyer1024, Nov 26, 2007
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  3. sparky672

    sparky672

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    Can you please elaborate on this?

    Is your screen on for an hour straight? Or are you using the "display off" feature? If so, how many times per hour are you touching the screen to wake-up? What default level of screen brightness do you have set? How much is the thing talking to you and how loud is the volume? All these things will consume the most power.


    As far as your other comments, I believe that all modern electronic devices will not allow an overcharge. Lithium batteries are fragile/dangerous enough by themselves, so I doubt that manufacturers would intentionally allow a charger to push them past their charging limits. I don't think since the old NiCad days, you've seen any charging system that just keeps going & going after a full charge... IMHO.
     
    sparky672, Nov 26, 2007
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  4. sparky672

    Hanaki

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    I just purchased the Tom Tom One LE and I plan to use it for biking also. I have read on this forum that you can purchase a external usb power supply that will extend your battery life. One is pretty small and takes a few AA batteries. It is pretty small and very portable. You just need to also buy some type of cover as these units are not water proof.
     
    Hanaki, Nov 27, 2007
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  5. sparky672

    sparky672

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    That's not a bad idea but you're not going to get much life out of a few AA batteries.

    Those USB battery power supplies were originally designed for iPods.... Think about it... the internal battery on an iPod is much smaller yet lasts 10 times longer than the TomTom's. A few AA batteries are perfect for iPods.

    Since we're talking about a bicycle, you could even mount a small 12 volt rechargeable someplace, then wire up a 12 volt socket... then plug in your regular TomTom car cord.

    Depending on the Amp-Hour rating, I'd expect a small 12-volt to be able to easily run a TomTom all day long before re-charging. It couldn't weigh more than a couple/few pounds... mounted under the seat, you wouldn't notice the extra weight. Unless you're a professional racer, who cares if you're bike is going to weigh a few more pounds?

    Somebody tell me the TomTom ONE's power consumption in milliwatts and I'll figure out what size 12 volt would work.

    (these tiny 12 volts can be re-charged with car battery chargers set to trickle)

    I wouldn't be biking in the rain but would have my zipper case with me in the event.
     
    sparky672, Nov 27, 2007
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  6. sparky672

    sparky672

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    Power Pack for Bicycle

    I never did find out what the exact power consumption is for the ONE 3rd Ed. I couldn't even find the power consumption specs for any TomTom.

    NOTE: I am a degreed Electrical Engineer. I'll keep this discussion as simple as possible, yet the electrical terminology and descriptions will be accurate.

    For now, I'll use numbers from a Magellan Maestro 3100 as an approximate starting point.

    With a 1200 mAH capacity battery and an approximate 3 hour battery life, we can assume the Magellan consumes approximately 400 mA of current at any given time.

    *********************************

    Voltage: 5 Volts (USB port)
    Current in milli-Amps: 400 mA (rough guess only)
    Power in Watts: 2 Watts (calculated)

    If we want to just use the Car Cigarette Lighter Cord/Adapter, we'll need a 12 Volt battery.

    Now we'll need to figure out the Current draw at this new higher voltage...

    (400 mA)*(5 volts) / (12 volts) = 167 mA

    So at 12 volts we'll be drawing 167 mA from the battery.

    *********************************

    Let's look at one specific 12 Volt battery. This one is small and only weighs 3 pounds so you should be able to find a good place to attach to your bike. (5.3 x 2.6 x 2.4 inches)

    http://www.batteriesplus.com

    It's rated at 3.3 AH (Amp-Hours)

    This simply means that it can supply 3.3 Amps continuously for one hour before total discharge.

    3.3 Ah = 3300 mAh (milliAmp-Hours)

    Let's figure out how long it takes to discharge this battery if we draw 167 mA continuously.

    3300 mAh / 167 mA = 19.75 hours

    *********************************

    The great thing about using small 12 volt batteries is that you can charge many of them with an automobile trickle charger.

    Here are two chargers:

    500 mAh (6.6 hour recharge for battery above)

    http://www.batteriesplus.com/p-34554-werker-12v-500mah-automatic-agm-charger.aspx

    1000 mAh (3.3 hour recharge for battery above)

    http://www.batteriesplus.com/p-34553-werker-12v-1000mah-automatic-agm-charger.aspx

    *********************************

    To use a 12 volt battery with your TomTom's Car Cigarette Lighter Cord/Adapter, you'll need a standard socket.

    You can find these at most automobile parts stores. Here's an example:

    http://www.tessco.com

    *********************************

    Wire it up using almost any wire. Since you're only drawing 167 mA, any copper multi-stranded insulated automotive wire should do. 16 or 18 gauge will be way more than heavy enough. Since it's many times larger than electrically required, now make sure it's heavy enough to withstand getting easily pinched or cut by accident.

    Wire up the 12 Volt Lighter Socket with the positive (+) terminal to the center pin of the socket and the negative (-) terminal to the shell.

    IMPORTANT: Make sure your polarity is correct. Check and double-check the positive and negative wires. Reversing these wires might blow your device. Sometimes safety circuits are built-in but the only way to find out is the hard way. So make sure the wires are correct!

    *********************************

    You can use any rechargable 12 Volt battery & recharger you like. If you know the Amp-Hour (AH) rating, you can use the formula above to calculate how long a single charge will last.

    *********************************

    For safety, consider installing an inline fuse assembly. You can find these at the auto parts store too. Three Amps would be good. Don't be too concerned about the rating as 16 gauge wire can handle a lot more current than a few Amps. The fuse is in place in case you accidently pinch the wires together causing a short. Install it as close to the battery as possible.

    A note about Fuse Size: It needs to be larger than the what you'll be drawing from the socket or you'll blow it every time you plug in a device. It needs to be smaller than the capacity of your wire if you still want to protect the wiring. 18 gauge wire Ampacity is approximately 8 Amps. So a three Amp fuse is what I recommend. Five Amps will work too.

    *********************************

    Alternate installation. You could also install the cigarette lighter socket right at the battery negating the need to fuse any wiring. The TomTom cord itself is protected with its own 2 Amp fuse inserted into the side of the plug assembly. With your new socket wired right next to the battery, the chances of a wiring short between the battery and socket is greatly minimized.

    *********************************

    Now you have a bicycle with a 12-volt rechargeable power source and 12-volt cigarette lighter style socket. Fully charged, you'll be able to power your TomTom for nearly 20 hours without any power saving features enabled. Bring your cell phone cord too just in case. If you have a Motorola Razr, you won't need another cord because it's identical to the TomTom's cord.

    This project may require crimping connectors and soldering. Use your best judgement and don't tackle this project if you lack basic wiring skills.
     
    Last edited: Nov 30, 2007
    sparky672, Nov 28, 2007
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  7. sparky672

    sparky672

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    More Battery options.

    Here are some smaller battery options...

    this one will get you about 12 hours and it's flat for easier mounting, only 1.5 pounds too...

    2000 mAh (12 hours @ 167 mA) - 6 x 0.8 x 3.5 inches

    http://www.batteriesplus.com/p-32625-12v-2ah-agm-vrla.aspx


    More...

    Long and narrow, only 2 pounds...

    2300 mAh (13.75 hours @ 167 mA) - 7 x 1.4 x 2.4 inches

    http://www.batteriesplus.com/p-32623-12v-22ah-agm-vrla.aspx


    Very small, about 1.5 pounds...

    1300 mAh (7.8 hours @ 167 mA) - 3.8 x 1.7 x 2 inches

    http://www.batteriesplus.com/p-32615-12v-13ah-agm-vrla.aspx
     
    Last edited: Nov 30, 2007
    sparky672, Nov 30, 2007
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  8. sparky672

    AlphaTango

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    Has anyone successfully used a GO720 to plan a bicycle route that actually chooses bike paths rather than freeways or major roads that sometimes run parallel to bike paths - even when the bicycle planning option is chosen ?
    It doesn't seem to make much different to choose bicycle route or walking route !!!
    Thanks?
     
    AlphaTango, Apr 2, 2008
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  9. sparky672

    Smokiewolf

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    https://www.tomtomforums.com/showthread.php?p=56394#post56394
     
    Smokiewolf, Apr 2, 2008
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  10. sparky672

    F22

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    Sparky:

    I think you would be better served by using a handheld or hiking unit like my Garmin 76cs. It DOES routing although its screen is nowhere as large as an automotive unit it works for 8 or greater hours on two AA batteries (I really don't know what it is spec-ed for and may be twice that - I just never bothered to check it real time). In addition, to the battery life, the unit is waterproof.

    Their newer units can probably hold most maps you would need.
     
    F22, Apr 4, 2008
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  11. sparky672

    sparky672

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    Thank-you for the suggestions.

    I don't bike enough in uncharted areas to justify buying a second dedicated GPS though. I usually stick to the mapped roads.

    However, just the idea of plugging your TomTom into any 12 Volt source with the standard USB plug and car adapter should give people many new ideas, besides biking, on extending usage for huge numbers of hours.
     
    sparky672, Apr 4, 2008
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