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  1.    #1  
    Hi,

    I have a question on how I can hook up my Treo charger (for Treo 650/680) directly into my car's power without using the cigarette adapter.

    I would greatly appreciate it if there are any electrical engineer majors who can help me answer these questions and best address this as I have a couple of other things that I want to splice directly into my car power (iPod USB cable and GPS USB charger cable).

    I did this previously on a Whistler Radar decector (I spliced the cigarette adapter and hooked up the + end into the Radio Fuse and the other end to ground, and it worked fine). This way I can hide the cables nicely along the front dash and do not have to have ugly wires hanging from cigarette adapter to the front windshield.

    I am thinking of doing the same for the Palm USB charger (i.e. splicing a USB cable and hooking up Pin 1 + into a fuse and Pin 4 GND into the grounding of the car). However, I am a bit concerned about the following issues:

    1) Voltage differences
    2) Charging rate (Ampere or milliamp) resulting in overcharging of the battery (I switched to a Treo 680, and I definitely do not need more battery issues, lol)
    3) Charging rate when there are multiple devices attached to the same fuse in the car
    4) Charging mechanism within the Palm Treos (Treo 680 preferably or any other models)

    On issue #1, as the DC from cars have 12Volt and Palm typically are charged with 5V DC (USB from computers I believe run at 5V DC, 500ma, Palm OEM A/C Charger runs at 5.2V DC 1000ma and an aftermarket A/C charger I got runs at 5.0V DC 850ma). Does anyone know whether there will be any issue if I hook up the USB cable in such way (i.e. will it fry the Treo or does it have a voltage regulator whereby it can accept variable voltages up to 12V DC???). I know that this is not an iPod forum site, but if anyone have information on this about the 5G iPod, Nano and Mini, I would really love to hear your thoughts.

    On Issue #2, let's say the car is charging at a rate of 1500ma, that would certainly charge the battery quickly, but does the Treo have a smart charging mechanism within the Treo whereby it will automatically trickle charge and avoid overcharging the battery? Or is this mechanism typically stored in the charging adapter? If it is in the charging adapter, doesn't that mean it would be bad to charge your Treo or any of your Palm with a cheap OEM charging adapter since they may not have proper trickle charge mechanism built in?

    On Issue #3, let's say the car fuse you hook into charges at 1500ma, and you attach 3 devices to it, does that mean it splits the 1500ma into 500ma x 3, resulting in 500ma for each device? Or will it only divide the 500ma into the amount each device needs? (Say iPod draws only 300ma, and Treo can draw up to 1300ma, it will do iPod 300 and Treo 1200??)

    On Issue #4, I guess it's covered in issue #1 & #2.

    I understand this is a really longwinded message, but I am trying to improve the aesthetics inside my car and would greatly appreciate someone's help on this subject.

    Thanks in advance,

    Albert
  2. #2  
    I ran into the same dilemma when i was trying to figure out how i was going to setup my treo/gps mounts etc.. (http://discuss.treocentral.com/showthread.php?t=106413)

    My current setup exposes 2 usb ports in my car:
    - 1 hidden in the center console where I have my GPS unit connected to all the time
    - another on the side of my center dash where I occasionally will charge either my treo or BT headset.
    Both USB ports are essentially spliced off of my 12v cigaratte line: Under my center dash the line is spliced to a second 12v cig outlet, which has a 12v to dual usb port adaptor connected to it. From there I run wires to where my usb ports are mounted.

    Im not an electrical wiz, but heres what I believe:
    1) you'll need an adaptor to bring the 12v down to 5v..
    2) the mechanism is within device/battery, not within the charger.
    3) If you have multiple devices and they as a whole attempt to draw more power than is available, then you run the risk of blowing a fuse. So in the case where one device is drawing 300mA, and the other 1300mA, that would blow it. However, the devices rarely draw the max amperage (unless maybe its near dead? so i was told) On my car, the cig lighter is 12v 1A... and I often have my GPS & treo both charging on it all the time without any issues.
  3. #3  
    Quote Originally Posted by Comatose View Post
    Im not an electrical wiz, but heres what I believe:
    1) you'll need an adaptor to bring the 12v down to 5v..
    2) the mechanism is within device/battery, not within the charger.
    3) If you have multiple devices and they as a whole attempt to draw more power than is available, then you run the risk of blowing a fuse. So in the case where one device is drawing 300mA, and the other 1300mA, that would blow it. However, the devices rarely draw the max amperage (unless maybe its near dead? so i was told) On my car, the cig lighter is 12v 1A... and I often have my GPS & treo both charging on it all the time without any issues.
    That's not true. The cigarette lighter end-piece for Treo adapters or Car USB chargers, has circuitry that converts 12vdc down to 5vdc.

    If you wanted to wired a USB charger directly into your car, I think the easiest thing would be:

    1. Wire a Cigarette lighter socket (from RatShack or equiv) behind your dash and plug your USB cigarette lighter socket into it, then expose the USB port somewhere....
    or
    2. Open up the contents of one of these adapters and wire it in directly.

    You should try and stay under the max Amperage of your adapter. So..if your cig adapter is 1.5A, then that's 1500ma max. True it may work with more amperage, but there is more of a chance of burning out the cig adapter circuit.
  4.    #4  
    Quote Originally Posted by mogulman View Post
    That's not true. The cigarette lighter end-piece for Treo adapters or Car USB chargers, has circuitry that converts 12vdc down to 5vdc.

    If you wanted to wired a USB charger directly into your car, I think the easiest thing would be:

    1. Wire a Cigarette lighter socket (from RatShack or equiv) behind your dash and plug your USB cigarette lighter socket into it, then expose the USB port somewhere....
    or
    2. Open up the contents of one of these adapters and wire it in directly.

    You should try and stay under the max Amperage of your adapter. So..if your cig adapter is 1.5A, then that's 1500ma max. True it may work with more amperage, but there is more of a chance of burning out the cig adapter circuit.
    Thank you both for your input. And that's a very nice/clean setup Comatose!

    I ended up wiring a cigarette->USB adapter to a spare wire that I cut from my speaker wire (hooking up the + to the tip of the cigarette adapter and negative to the side), and tied the other end into the fuse box of an unused electrical option in the car and the car's ground. This way I'll still have the tiny fuse in the cigarette->USB adapter to save my Treo in case there's a huge current coming through.

    Running it this way worked fine and allowed me to power my Palm directly from the car's electrical wiring w/o ugly looking cigarette adapter taking up spaces. The only thing that I am worried is that the cigarette->USB adapter stays on even when I turn the car off (it's on a New Audi A4), so I worry that it may drain the battery since I only use my car during the weekend and park it in the garage during weekdays.

    Since I don't have anything plugged into the cigarette->USB adapter, I imagine the only power it's drawing from the car battery is the tiny red LED power indicator and whatever the 12V->5V conversion electrical component is using... I'm just too chicken to try it out to see whether it would drain my battery or not (since I don't want to have a dead car battery in the garage for a brand new car)..

    Thanks again for all the help.
  5. #5  
    Oh right, i didn't quite read what he said his initial intentions were :P
    But what you suggested is what basically what I did, and has been working quite well~

    Quote Originally Posted by mogulman View Post
    That's not true. The cigarette lighter end-piece for Treo adapters or Car USB chargers, has circuitry that converts 12vdc down to 5vdc.

    If you wanted to wired a USB charger directly into your car, I think the easiest thing would be:

    1. Wire a Cigarette lighter socket (from RatShack or equiv) behind your dash and plug your USB cigarette lighter socket into it, then expose the USB port somewhere....
    or
    2. Open up the contents of one of these adapters and wire it in directly.

    You should try and stay under the max Amperage of your adapter. So..if your cig adapter is 1.5A, then that's 1500ma max. True it may work with more amperage, but there is more of a chance of burning out the cig adapter circuit.

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