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  1. yazyazoo's Avatar
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       #1  
    I just got GPS for my 700wx and fiancee's 755p. Now we need to get a car charger. I see some cheap ones on ebay for 3 dollar and shipping. It says it has a chip to stop the charging.

    Do you guys think generic chargers will ruin the battery? Should I buy the Oem PALM car charger? I bought a quick car charger for my old cellphone and it seemed to make my battery die faster. Maybe it's in my mind.

    What do you guys think? Generic or Oem?
  2. #2  
    This is a good question and I am curious to review the responses of others.

    In my view, the primary distinction between chargers is whether or not they regulate voltage by imposing a high-frequency duty cycle on the output or simply use a deterministically-biased BJT or FET. Whereas the former is better for power efficiency, cheaply-designed switching-type units can cause strong RF noise (fixed by adding capacitors). In either case, the end result of either type should be the same: a regulated power supply which accurately provides a constant voltage regardless of the load (up to the designed amperage of course).

    Although I haven't scrapped a Treo to inspect the charging circuitry, my experience with similar devices is that the 'charger' is simply a constant voltage source (which should be able to sustain the expected load) and the actual monitoring circuitry which controls the charging rate (via slowly ramping the voltage to control current draw or otherwise 'trickle charging') is contained within the handset itself. As such, I think that nearly any charger is sufficient for charging a Treo and my feeling is that the Palm-branded ones are simply overpriced.

    The charger market is troubling-- it is sad that the manufacturers do not settle on a single charger voltage/current/interface so that we might only need one for all devices. But of course branding and the extra markets which the companies develop around charging and other support hardware which is 'uniquely designed' (e.g. the Palm charger socket-- it is square. Why is that? So you have to buy a Palm charger. In fact, this adds a large degree of frustration during use since one must rotate the plug in the socket until it will mate-- this demonstrates the desire to make money over the will to produce a superior product).

    In short, I think any *cheap* charger is fine as long as it produces the correct voltage and current (this is easily checked and all of mine are within spec.). Most of my chargers were bought for <$5 each from Ebay and I haven't had a problem yet. The major problem I can imagine is if a cheap charger produces too much voltage. This could of course fry a phone, so it might be worth measuring the output before using a cheap charger.
    Last edited by 700p_isaheadache; 09/22/2007 at 03:54 PM. Reason: changed "OEM" to *cheap* per Frankxs
  3. #3  
    Quote Originally Posted by yazyazoo View Post
    I just got GPS for my 700wx and fiancee's 755p. Now we need to get a car charger. I see some cheap ones on ebay for 3 dollar and shipping. It says it has a chip to stop the charging.

    Do you guys think generic chargers will ruin the battery? Should I buy the Oem PALM car charger? I bought a quick car charger for my old cellphone and it seemed to make my battery die faster. Maybe it's in my mind.

    What do you guys think? Generic or Oem?
    I'd buy OEM. But I'd be happy to buy it on eBay... long as it was OEM.

    Here's one for 8 bucks... +shipping 6 bucks.... 14 total.

    http://cgi.ebay.com/ws/eBayISAPI.dll...ype=osi_widget

    -Frank
    Last edited by Frankxs; 09/22/2007 at 10:13 AM.
  4. #4  
    Quote Originally Posted by 700p_isaheadache View Post
    In short, I think any OEM charger is fine as long as it produces the correct voltage and current
    Why would the Original Equipment Manufacturer (OEM) supply a non-compatible charger with their phone?

    -Frank
  5. #5  
    Thanks for catching that, it was the end of a long day when I wrote that text (will edit post to fix)... I meant to say 'cheap' instead of 'OEM'.

    The point that follows and agrees with your sentiment is that the OEM chargers can have tighter electronics and thus may tend to be more within spec. (e.g. better-designed chargers might span 4.8-5.2 V at 1 sigma yet cheaper ones might span 4.5-5.5 V at 1 sigma). A good example of this is an old Motorola charger I had that literally made the backlight of an old phone 'too bright' when I would plug it in. Obviously the setpoint of its voltage regulator was too high and the phone couldn't sufficiently preprocess the signal once injected. It isn't likely to find a 'real' voltage regulator inside the handset circuitry since overvoltages can cause heat, which the phone is not likely to be designed to dissipate (this is of course why we have external chargers for things like phones and laptops etc.).

    Anyway, I presumably belabored the point enough to get people thinking about chargers. That said, unless you want to check the voltage of a cheap charger yourself (which I always do), maybe the OEM chargers are worth pursuing to avoid the hassle. These days I have one charger with a separate plug for every (small) device I own trailing from it (multiple regulators inside) and this is great for travel. I simply cut the cords from all the needed chargers, used 780x voltage regulators and a 1A transformer (with a few diodes and caps of course for those following), and can charge 3 or 4 devices at once (most things seem do draw around 300mA). The charger plugs into the car or wall, and can power the 5V max devices when plugged into the USB socket of my computer. In the end, perhaps the best thing to do is design your own charger

    Quote Originally Posted by Frankxs View Post
    Why would the Original Equipment Manufacturer (OEM) supply a non-compatible charger with their phone?

    -Frank
    Last edited by 700p_isaheadache; 09/22/2007 at 04:23 PM.

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